Moving body, sheet member, and manufacturing device

Abstract

Provided is a moving body capable of moving in a fluid, wherein a surface of the moving body includes a first surface to which a first sheet member having a first riblet structure formed thereon is attached, and a second surface to which a second sheet member having a second riblet structure formed thereon is attached, a characteristic of the first riblet structure being different from a characteristic of the second riblet structure.

Description

Mobile body, sheet member and manufacturing device

[0001] The present invention relates to the technical fields of, for example, a sheet member having a riblet structure formed on its surface, a moving body to which the sheet member is attached, and a mold used for imprint molding the sheet member.

[0002] Patent Document 1 describes an aircraft having a fuselage with a riblet structure formed on its surface. In this case, it is required to effectively utilize the characteristics of the riblet structure.

[0003] US Patent Application Publication No. 2017 / 0144255

[0004] According to a first aspect, a moving body capable of moving through a fluid is provided, the surface of the moving body including a first surface to which a first sheet member having a first riblet structure formed thereon is attached, and a second surface to which a second sheet member having a second riblet structure formed thereon is attached, and the characteristics of the first riblet structure are different from the characteristics of the second riblet structure.

[0005] According to a second aspect, there is provided a sheet member, the surface of which includes a first surface on which a first riblet structure is formed and a second surface on which a second riblet structure is formed, and the characteristics of the first riblet structure are different from the characteristics of the second riblet structure.

[0006] According to a third aspect, there is provided a moving body that is movable through a fluid, and has the sheet member provided by the second aspect attached to at least a portion of the surface of the moving body.

[0007] According to a fourth aspect, there is provided a moving body capable of moving through a fluid, in which a plurality of sheet members provided by the second aspect are attached to at least a portion of the surface of the moving body.

[0008] According to a fifth aspect, there is provided a manufacturing apparatus for manufacturing the sheet member provided by the second aspect.

[0009] According to a sixth aspect, a moving body capable of moving through a fluid is provided, the surface of the moving body including a first surface to which a first sheet member having a first structure formed thereon is attached, and a second surface to which a second sheet member having a second structure formed thereon is attached, and the characteristics of the first structure are different from the characteristics of the second structure.

[0010] According to a seventh aspect, a sheet member is provided, wherein the surface of the sheet member includes a first surface on which a first structure is formed and a second surface on which a second structure is formed, and the characteristics of the first structure are different from the characteristics of the second structure.

[0011] According to an eighth aspect, there is provided a moving body that is movable through a fluid, and has the sheet member provided by the seventh aspect attached to at least a portion of the surface of the moving body.

[0012] According to a ninth aspect, there is provided a moving body capable of moving through a fluid, in which a plurality of sheet members provided by the seventh aspect are attached to at least a portion of the surface of the moving body.

[0013] According to a tenth aspect, there is provided a manufacturing apparatus for manufacturing the sheet member provided by the seventh aspect.

[0014] FIG. 1(a) is a perspective view showing the appearance of the libretto sheet of this embodiment, and FIG. 1(b) is a cross-sectional view (II' cross-sectional view of FIG. 1(a)) showing the structure of the libretto sheet of this embodiment. FIG. 2(a) is a perspective view showing the libretto structure, FIG. 2(b) is a cross-sectional view (II-II' cross-sectional view of FIG. 2(a)) showing the libretto structure, and FIG. 2(c) is a top view showing the libretto structure. FIG. 3(a) is a front view showing an aircraft, which is an example of an object to which a libretto sheet can be attached, and FIG. 3(b) is a side view showing an aircraft, which is an example of an object to which a libretto sheet can be attached. FIG. 4 is a side view showing an aircraft (particularly, the fuselage of the aircraft), which is an example of an object. Each of FIGS. 5(a) to 5(c) shows convex structures formed on a libretto sheet attached to an object. FIG. 6 is a plan view showing the shape of the libretto sheet (particularly, the shape in a plan view). FIG. 7 is a plan view showing a libretto sheet of a second embodiment. Each of Figures 8(a) to 8(c) shows convex structures formed on the libretto sheet of the second embodiment. Each of Figures 9(a) to 9(d) is a plan view showing an arrangement pattern of multiple partial structure surfaces in the libretto sheet of the second embodiment. Figure 10 is a cross-sectional view schematically showing the configuration of a manufacturing apparatus (processing apparatus) that manufactures a libretto sheet. Figure 11 is a system configuration diagram showing the system configuration of a manufacturing apparatus (processing apparatus) that manufactures a libretto sheet. Figure 12 is a perspective view schematically showing the structure of a manufacturing apparatus (first imprint molding apparatus) that manufactures a libretto sheet. Figure 13 is a perspective view schematically showing the structure of a manufacturing apparatus (second imprint molding apparatus) that manufactures a libretto sheet.

[0015] Next, embodiments of a moving body, a sheet member, and a manufacturing apparatus will be described with reference to the drawings.

[0016] (1) Libretto sheet 1 of the first embodiment First, the libretto sheet 1 of the first embodiment will be described. In the following description, the libretto sheet 1 of the first embodiment will be referred to as the “libretto sheet 1 a.”

[0017] (1-1) Structure of the Libretto Sheet 1a First, the structure of the libretto sheet 1a will be described with reference to Figures 1(a) and 1(b). Figure 1(a) is a perspective view showing the appearance of the libretto sheet 1a of the first embodiment, and Figure 1(b) is a cross-sectional view (cross-sectional view taken along II' in Figure 1(a)) showing the structure of the libretto sheet 1a of the first embodiment.

[0018] As shown in FIGS. 1( a) and 1(b), the libretto sheet 1a is a sheet member. The sheet member may be a film-like, sheet-like, layer-like, foil-like, tape-like, or band-like member. The sheet member may also be referred to as a film member. In the example shown in FIGS. 1(a) and 1(b), the Y-axis direction is the width direction of the libretto sheet 1a, and the Z-axis direction is the thickness direction of the libretto sheet 1a. The libretto sheet 1a is a sheet member whose thickness is much smaller than its width. As an example, the width of the libretto sheet 1a may be several centimeters or more, 10-odd centimeters or more, several tens of centimeters or more, or one meter or more. On the other hand, the thickness of the libretto sheet 1a may be one millimeter or less, one centimeter or less, or a few centimeters or less.

[0019] The libretto sheet 1a has a longitudinal shape extending along a length direction intersecting the width direction and the thickness direction. In other words, the libretto sheet 1a has a longitudinal shape in which the direction intersecting the width direction and the thickness direction is the longitudinal direction. In the example shown in Figures 1(a) and 1(b), the X-axis direction is the length direction (longitudinal direction) of the libretto sheet 1a. As an example, the length of the libretto sheet 1a may be several centimeters or more, a dozen centimeters or more, several tens of centimeters or more, one meter or more, a dozen meters or more, or several tens of meters or more.

[0020] However, the libretto sheet 1a does not have to have a longitudinal shape extending along a length direction intersecting the width direction and thickness direction. The longitudinal direction of the libretto sheet 1a may be the width direction. Furthermore, the libretto sheet 1a may have a rectangular shape in plan view. As an example, the libretto sheet 1a extending along the length direction may be divided along the length direction into multiple sheet members each having a rectangular shape. Furthermore, the libretto sheet 1a may have a square shape in plan view. As an example, the libretto sheet 1a extending along the length direction may be divided along the length direction into multiple sheet members each having a square shape.

[0021] As shown in FIG. 1( b ), the riblet sheet 1 a may include an adhesive layer 11 and a coating layer 12 .

[0022] The adhesive layer 11 is a layer containing an adhesive for attaching the coating layer 12 to the object OBJ (for example, a moving object, which will be described later). Therefore, the libretto sheet 1a may be attached to the object OBJ via the adhesive layer 11. Note that the libretto sheet 1a does not have to include the adhesive layer 11. In this case, when attaching the libretto sheet 1a to the object OBJ, an operator may apply adhesive between the object OBJ and the libretto sheet 1a.

[0023] The coating layer 12 is a layer having a predetermined function. In the example shown in FIG. 1( b), the coating layer 12 includes a paint layer 121 and a coating layer 122. The paint layer 121 is a layer containing paint of a predetermined color. The coating layer 122 is a layer that protects the surface of the paint layer 121. The coating layer 122 may include a clear layer that is transparent in the visible light range. However, the coating layer 12 does not necessarily include at least one of the paint layer 121 and the coating layer 122. The coating layer 12 may include a layer other than at least one of the paint layer 121 and the coating layer 122. For example, the coating layer 12 may include an anti-reflection layer that prevents light from reflecting on the surface of the coating layer 12. The coating layer 12 may also include an anti-glare layer that reduces the glossiness of the surface of the coating layer 12. Alternatively, the coating layer 122 may function as at least one of the anti-reflection layer and the anti-glare layer.

[0024] A riblet structure RB is formed on the surface of the libretto sheet 1a. However, in Figures 1(a) and 1(b), the riblet structure RB formed on the surface of the libretto sheet 1a is omitted for simplicity of the drawings. The riblet structure RB formed on the surface of the libretto sheet 1a will be described in detail later with reference to Figures 2(a) to 2(c). In the following description, the surface of the libretto sheet 1a on which the riblet structure RB is formed will be referred to as the "riblet structure surface 130." Figures 1(a) and 1(b) show an example in which the surface of the coating layer 12 is the riblet structure surface 130. In other words, Figures 1(a) and 1(b) show an example in which the riblet structure RB is formed on the surface of the coating layer 12.

[0025] An example of the riblet structure RB is shown in Figures 2(a) to 2(c), where Figure 2(a) is a perspective view showing the riblet structure RB, Figure 2(b) is a cross-sectional view (cross-sectional view taken along II-II' in Figure 2(a)) showing the riblet structure RB, and Figure 2(c) is a top view showing the riblet structure RB.

[0026] As shown in Figures 2(a) to 2(c), the riblet structure RB may include a plurality of convex structures 191. Each of the plurality of convex structures 191 may extend along a predetermined extension direction. In this case, the riblet structure RB may include a plurality of convex structures 191 extending along the predetermined extension direction. Each of the plurality of convex structures 191 may be arranged along a predetermined arrangement direction. In this case, the riblet structure RB may include a plurality of convex structures 191 arranged along the predetermined arrangement direction.

[0027] As an example, the riblet structure RB may include a structure in which a plurality of convex structures 191 extending along a predetermined stretching direction are arranged along a predetermined arrangement direction that intersects the predetermined stretching direction. In other words, the riblet structure RB may include a structure in which the convex structures 191 formed to extend along the predetermined stretching direction are lined up along the predetermined arrangement direction. Each of the stretching direction and the arrangement direction may be a direction that intersects the height direction (described later) in which the convex structures 191 protrude. Furthermore, one of the stretching direction and the arrangement direction may be the longitudinal direction of the liblet sheet 1a, and the other of the stretching direction and the arrangement direction may be the lateral direction of the liblet sheet 1a. In the example shown in Figures 2(a) to 2(c), the riblet structure RB includes a structure in which a plurality of convex structures 191 extending along the X-axis direction, which is the longitudinal direction (length direction) of the liblet sheet 1a, are arranged along the Y-axis direction, which is the width direction of the liblet sheet 1a. That is, Figures 2(a) to 2(c) show an example in which the predetermined extension direction is the X-axis direction and the predetermined arrangement direction is the Y-axis direction that intersects (typically, is perpendicular to) the X-axis direction.

[0028] The convex structures 191 are structures that protrude from the surroundings along a predetermined height direction. The convex structures 191 are structures that protrude from the surroundings along a predetermined height direction that intersects both the predetermined extension direction in which the convex structures 191 extend and the predetermined arrangement direction in which the convex structures 191 are arranged. The height direction may be the thickness direction of the libretto sheet 1a. In the example shown in Figures 2(a) to 2(c), the convex structures 191 are structures that protrude from the surroundings along the Z-axis direction, which is the thickness direction of the libretto sheet 1a. In other words, Figures 2(a) to 2(c) show an example in which the predetermined height direction is the Z-axis direction that intersects (typically, is perpendicular to) the X-axis direction and the Y-axis direction. The convex structures 191 may include a protruding structure that protrudes from the surroundings. The convex structures 191 may include a convex structure that protrudes from the surroundings. The convex structures 191 may include a mountain-shaped structure that protrudes from the surroundings.

[0029] The convex structure 191 has, for example, a pair of side surfaces 1911 and 1912 facing opposite to each other. Note that in the first embodiment, "a state in which one surface and the other surface face opposite to each other" may mean, for example, a state in which one surface faces one side of an axis intersecting the one surface and the other surface, while the other surface faces the other side along the same axis (i.e., the opposite side from the one side). In the example shown in FIGS. 2( a) to 2(c), the convex structure 191 has a side surface 1911 facing the -Y side and a side surface 1912 facing the +Y side. Each of the pair of side surfaces 1911 and 1912 is a flat surface. However, at least one of the pair of side surfaces 1911 and 1912 may include a curved surface.

[0030] The pair of side surfaces 1911 and 1912 may be non-parallel to each other. In this case, the pair of side surfaces 1911 and 1912 of the convex structure 191 may be connected via one end thereof (in the examples shown in FIGS. 2( a ) to 2 ( c ), the upper end portions on the +Z side). The portion where the pair of side surfaces 1911 and 1912 of the convex structure 191 are connected constitutes a corner portion 1913 of the convex structure 191. The corner portion 1913 of the convex structure 191 may constitute the vertex of the convex structure 191. The corner portion 1913 of the convex structure 191 may constitute the ridge line of the convex structure 191. The corner portion 1913 of the convex structure 191 may constitute the boundary portion between the pair of side surfaces 1911 and 1912 of the convex structure 191. In this case, the pair of side surfaces 1911 and 1912 may be considered to be connected via the corner portion 1913 of the convex structure 191. In the example shown in FIGS. 2( a ) to 2 ( c ), a pair of side surfaces 1911 and 1912 are connected so that the upper end of the side surface 1911 and the upper end of the side surface 1912 are in contact with each other.

[0031] The convex structure 191 may be a structure formed by a pair of side surfaces 1911 and 1912. The convex structure 191 may be a structure including the pair of side surfaces 1911 and 1912 on its surface. In this case, the shape of a cross section of the convex structure 191 including the Z axis may be a triangular shape. In this case, the shape of a cross section of the convex structure 191 including the Z axis may be a symmetrical triangular shape, or may be an asymmetrical triangular shape. However, the shape of a cross section of the convex structure 191 including the Z axis may have any shape other than a triangular shape.

[0032] The side surfaces 1911 and 1912 may be referred to as inclined surfaces 1911 and 1912, respectively. The riblet structure surface 130 may be considered to include the side surfaces 1911 and 1912. Furthermore, if the corner portion 1913 (vertex or ridge line) of the convex structure 191 is not a corner but a curved surface (convex surface), the riblet structure surface 130 may be considered to include the corner portion 1913.

[0033] Between adjacent convex structures 191, groove structures 192 are formed that are recessed compared to the surrounding area. For this reason, the riblet structure RB may include a structure in which a plurality of groove structures 192 extending along a predetermined extension direction are arranged along a predetermined arrangement direction. In other words, the riblet structure RB may include a structure in which groove structures 192 formed to extend along a predetermined extension direction are lined up along a predetermined arrangement direction. Note that the groove structures 192 may be considered to be recessed structures with respect to the vertices or ridgelines (for example, the above-mentioned corners 1913) of the convex structures 191.

[0034] The groove structure 192 may be considered to be a structure located between a side surface 1911 of one convex structure 191 and a side surface 1912 of another convex structure 191 adjacent to the one convex structure 191 along the arrangement direction in which the convex structures 191 are arranged. Specifically, the side surface 1911 of one convex structure 191 and the side surface 1912 of another convex structure 191 adjacent to the one convex structure 191 along the arrangement direction in which the convex structures 191 are arranged may be connected via a boundary portion 1914 connecting their other end portions (lower end portions on the -Z side in the example shown in FIGS. 2( a) to 2(c)). In other words, the side surfaces 1911 and 1912 that are provided on two adjacent convex structures 191 and that face each other may be connected via the boundary portion 1914 that forms the boundary between the two adjacent convex structures 191. In the example shown in Figures 2(a) to 2(c), the boundary portion 1914 includes a surface that intersects with each of the side surfaces 1911 and 1912 to which the boundary portion 1914 is connected. In this case, the groove structure 192 may be a structure formed by the boundary portion 1914. The groove structure 192 may be a structure that includes a groove that the boundary portion 1914 faces. The boundary portion 1914 may be considered to be the bottom surface of the groove structure 192. In this case, the boundaries between each of the side surfaces 1911 and 1912 and the boundary portion 1914 may be used as the boundary between the convex structure 191 and the groove structure 192. The groove structure 192 may also be referred to as a groove-shaped structure or a concave structure.

[0035] However, in some cases, groove structure 192 may be considered to be a structure formed by boundary portion 1914 and side surfaces 1911 and 1912 connected by boundary portion 1914. Groove structure 192 may be considered to be a structure including grooves facing boundary portion 1914 and side surfaces 1911 and 1912 connected by boundary portion 1914. Furthermore, riblet structure surface 130 may be considered to include boundary portion 1914 (e.g., the bottom surface of groove structure 192) in addition to or instead of side surfaces 1911 and 1912.

[0036] The multiple convex structures 191 may be formed so that the multiple convex structures 191 are arranged regularly. For example, the multiple convex structures 191 may be formed so that the multiple convex structures 191 are arranged at an equal pitch along a predetermined arrangement direction. For example, the multiple convex structures 191 may be formed so that a structural group including at least two convex structures 191 is arranged at an equal pitch along a predetermined arrangement direction. In the first embodiment, the multiple convex structures 191 may be formed so that at least two convex structures 191 are arranged regularly according to a first rule in a first portion of the surface of the riblet sheet 1a, and so that at least two convex structures 191 are arranged regularly according to the same first rule in a second portion of the surface of the riblet sheet 1a. However, as will be described in a second embodiment below, the multiple convex structures 191 may be formed so that at least two convex structures 191 are arranged regularly according to a first rule in a first portion of the surface of the libretto sheet 1a, while at least two convex structures 191 are arranged regularly according to a second rule that is different from the first rule in a second portion of the surface of the libretto sheet 1a. Note that, because the convex structures 191 and the groove structures 192 are formed alternately, the state in which the multiple convex structures 191 are arranged regularly may be considered equivalent to the state in which the multiple groove structures 192 are arranged regularly.

[0037] The height H_rb of at least one of the multiple convex structures 191 may be set to a height determined according to the pitch P_rb of the convex structures 191. For example, the height H_rb of at least one of the multiple convex structures 191 may be less than or equal to the pitch P_rb of the convex structures 191. For example, the height H_rb of at least one of the multiple convex structures 191 may be less than half the pitch P_rb of the convex structures 191. Furthermore, the height H_rb of at least one of the multiple convex structures 191 may be within a range of −1 / 2±10% of the pitch P_rb of the convex structures 191. Note that the height H_rb may be the height from the bottom surface of the groove structure 192 (i.e., the boundary portion 1914). Furthermore, the height H_rb may be referred to as the depth from the vertex or ridge line (i.e., the corner portion 1913) of the convex structure 191.

[0038] The riblet structure RB may be used as a structure capable of reducing the resistance to a fluid (particularly, at least one of frictional resistance and turbulent frictional resistance) of the surface of the riblet sheet 1a (typically, the riblet structure surface 130). In this case, the riblet structure surface 130 on which the riblet structure RB is formed may be considered to be a surface capable of reducing the resistance to a fluid of the surface of the riblet sheet 1a (typically, the riblet structure surface 130).

[0039] The riblet sheet 1a on which the riblet structure RB is formed may be attached to an object OBJ via an adhesive layer 11. In this case, the riblet structure RB may be used as a structure capable of reducing the resistance (particularly, at least one of frictional resistance and turbulent frictional resistance) of the surface of the object OBJ to which the riblet sheet 1a is attached to a fluid. For this reason, the riblet sheet 1a may be attached to an object OBJ having a component installed (in other words, located) in a fluid. Note that the term "fluid" here refers to a medium (e.g., at least one of gas and liquid) flowing relative to the surface of the object OBJ. For example, if the surface of the object OBJ moves relative to the medium while the medium itself is stationary, this medium may also be referred to as a fluid. Note that the state in which the medium is stationary may also refer to a state in which the medium is not moving relative to a predetermined reference object (e.g., the ground surface).

[0040] (1-2) Example of Object OBJ to which Libretto Sheet 1a is Attached One example of an object OBJ to which the libretto sheet 1a is attached is a moving body. In particular, one example of an object OBJ to which the libretto sheet 1a is attached is a moving body that can move through a fluid. Examples of moving bodies include at least one of a railway vehicle, an automobile, an aircraft, a ship, a windmill, and a turbine. However, the libretto sheet 1a may be attached to an object OBJ other than the moving body.

[0041] For example, Figures 3(a) and 3(b) show an aircraft PL having a riblet sheet 1a attached to at least a portion of its surface. As shown in Figures 3(a) and 3(b), the riblet sheet 1a may be attached to at least a portion of the fuselage PL1 of the aircraft PL. The riblet sheet 1a may be attached to at least a portion of the main wing PL2 of the aircraft PL. The riblet sheet 1a may be attached to at least a portion of the vertical tail PL3 of the aircraft PL. The riblet sheet 1a may be attached to at least a portion of the horizontal tail PL4 of the aircraft PL.

[0042] When such a riblet sheet 1a is attached to at least a portion of the surface of a moving body (or any object OBJ, the same applies hereinafter), the moving body becomes more easily movable relative to the fluid. This reduces the resistance that hinders the movement of the moving body relative to the fluid, leading to energy savings. In other words, it becomes possible to manufacture an environmentally friendly moving body. For example, when the riblet sheet 1a is attached to at least a portion of the surface of an aircraft PL, the resistance that hinders the movement of the aircraft PL is reduced, leading to fuel savings for the aircraft. For example, when the riblet sheet 1a is attached to at least a portion of the surface of a wind turbine, the resistance that hinders the movement (typically, rotation) of the wind turbine is reduced, leading to higher efficiency of the wind turbine. For example, when the riblet sheet 1a is attached to at least a portion of the surface of an engine turbine (particularly, a turbine blade), the resistance that hinders the movement (typically, rotation) of the engine turbine is reduced, leading to higher efficiency and energy savings for the engine turbine. For example, when the riblet sheet 1a is attached to at least a portion of the surface of a power generation turbine (particularly a turbine blade), the resistance that hinders the movement (typically, rotation) of the power generation turbine is reduced, leading to higher efficiency of the power generation turbine (i.e., improved power generation efficiency). As a result, the riblet sheet 1a may be able to contribute to "13.-2#2 Reduction of total greenhouse gas emissions per year," one of the goals set out in Goal 13 of the United Nations-led Sustainable Development Goals (SDGs), "Take urgent action to combat climate change and its impact."

[0043] (1-3) Attaching Multiple Libretto Sheets 1a to Object OBJ (1-3-1) Multiple Libretto Sheets 1a In the first embodiment, multiple libretto sheets 1a may be attached to the surface of the object OBJ. In particular, in the first embodiment, multiple libretto sheets 1a, each having multiple types of libretto structures RB formed thereon, may be attached to the surface of the object OBJ. In other words, multiple libretto sheets 1a having different libretto structures RB may be attached to the surface of the object OBJ.

[0044] For example, Figure 4 is a side view showing an aircraft PL (particularly, a fuselage PL1 of the aircraft PL), which is an example of an object OBJ. In this case, a first libretto sheet 1a-1 having a first type of libretto structure RB formed thereon, a second libretto sheet 1a-2 having a second type of libretto structure RB formed thereon, ..., an Nth libretto sheet 1a-N having an Nth type of libretto structure RB formed thereon (where N is a constant representing an integer greater than or equal to 2) may be attached to the surface of the object OBJ (i.e., the surface of the aircraft PL). In other words, the surface of the object OBJ may include a first surface Os-1 having the first libretto sheet 1a-1 attached thereto, a second surface Os-2 having the second libretto sheet 1a-2 attached thereto, ..., an Nth surface Os-N having the Nth libretto sheet 1a-N attached thereto. In other words, the surface of the object OBJ may include a k-th surface Os-k to which the k-th (where k is a variable indicating an integer greater than or equal to 1 and less than or equal to a constant N) libretto sheet 1a-k is attached. The k-th surface Os-k may be a surface that has been set in advance on the surface of the object OBJ as the surface to which the k-th libretto sheet 1a-k should be attached. In this case, the k-th libretto sheet 1a-k may be attached to the k-th surface Os-k that has been set in advance on the surface of the object OBJ. Alternatively, the surface of the object OBJ to which the k-th libretto sheet 1a-k is attached may be used as the k-th surface Os-k. In this case, the k-th libretto sheet 1a-k may be attached at any position on the surface of the object OBJ, and the surface of the object OBJ to which the k-th libretto sheet 1a-k is actually attached may be used as the k-th surface Os-k.

[0045] Figure 4 shows an example in which a first libretto sheet 1a-1, a second libretto sheet 1a-2, a third libretto sheet 1a-3, and a fourth libretto sheet 1a-4 are attached to the surface of an object OBJ. That is, Figure 4 shows an example in which the surface of the object OBJ includes a first side Os-1 to which the first libretto sheet 1a-1 is attached, a second side Os-2 to which the second libretto sheet 1a-2 is attached, a third side Os-3 to which the third libretto sheet 1a-3 is attached, and a fourth side Os-4 to which the fourth libretto sheet 1a-4 is attached.

[0046] The surface of the object OBJ may include a single k-th surface Os-k. For example, the surface of the object OBJ may include a single first surface Os-1. For example, the surface of the object OBJ may include a single second surface Os-2. Alternatively, the surface of the object OBJ may include a plurality of k-th surfaces Os-k, each located at a plurality of different positions on the surface of the object OBJ. For example, the surface of the object OBJ may include a plurality of first surfaces Os-1, each located at a plurality of different positions on the surface of the object OBJ. For example, the surface of the object OBJ may include a plurality of second surfaces Os-2, each located at a plurality of different positions on the surface of the object OBJ.

[0047] A single libretto sheet 1a-k may be attached to a single k-th surface Os-k. For example, a single first libretto sheet 1a-1 may be attached to a single first surface Os-1. For example, a single second libretto sheet 1a-2 may be attached to a single second surface Os-2. Alternatively, multiple libretto sheets 1a-k may be attached to a single k-th surface Os-k. For example, multiple first libretto sheets 1a-1 may be attached to a single first surface Os-1. For example, multiple second libretto sheets 1a-2 may be attached to a single second surface Os-2.

[0048] The characteristics of the first type of riblet structure RB to the characteristics of the Nth type of riblet structure RB may be different from one another. For example, the characteristics of the first type of riblet structure RB may be different from the characteristics of the second type of riblet structure RB to the characteristics of the Nth type of riblet structure RB. For example, the characteristics of the second type of riblet structure RB may be different from the characteristics of the first type of riblet structure RB and the characteristics of the third type of riblet structure RB to the characteristics of the Nth type of riblet structure RB. For example, the characteristics of the kth type of riblet structure RB may be different from the characteristics of the first type of riblet structure RB to the characteristics of the k-1th type of riblet structure and the characteristics of the k+1th type of riblet structure RB to the characteristics of the Nth type of riblet structure RB. For example, the characteristics of the Nth type of riblet structure RB may be different from the characteristics of the first type of riblet structure RB to the characteristics of the N-1th type of riblet structure RB.

[0049] The characteristics of the riblet structure RB may include the pitch P_rb of the convex structures 191 included in the riblet structure RB. The characteristics of the riblet structure RB may include the height H_rb of the convex structures 191 included in the riblet structure RB in addition to or instead of the pitch P_rb. The characteristics of the riblet structure RB may include the extension direction of the convex structures 191 included in the riblet structure RB in addition to or instead of at least one of the pitch P_rb and the height H_rb.

[0050] As a first example, as shown in FIG. 5( a), a first liblet sheet 1a-1#1 having a riblet structure RB formed thereon, in which a plurality of convex structures 191 are arranged at a first pitch P_rb, and a second liblet sheet 1a-2#1 having a riblet structure RB formed thereon, in which a plurality of convex structures 191 are arranged at a second pitch P_rb different from the first pitch P_rb, may be attached to the surface of an object OBJ. In other words, the surface of the object OBJ may include a first surface Os-1#1 having the first liblet sheet 1a-1#1 attached thereto and a second surface Os-2#1 having the second liblet sheet 1a-2#1 attached thereto. Note that the height H_rb of the convex structures 191 formed on the first liblet sheet 1a-1#1 may be the same as or different from the height H_rb of the convex structures 191 formed on the second liblet sheet 1a-2#1. The extension direction of the convex structure 191 formed on the first riblet sheet 1a-1#1 may be the same as or different from the extension direction of the convex structure 191 formed on the second riblet sheet 1a-2#1.

[0051] As a second example, as shown in FIG. 5( b), a first liblet sheet 1a-1#2 on which a riblet structure RB including convex structures 191 having a first height H_rb is formed, and a second liblet sheet 1a-2#2 on which a riblet structure RB including convex structures 191 having a second height H_rb different from the first height H_rb may be attached to the surface of an object OBJ. In other words, the surface of the object OBJ may include a first surface Os-1#2 on which the first liblet sheet 1a-1#2 is attached, and a second surface Os-2#2 on which the second liblet sheet 1a-2#2 is attached. Note that the pitch P_rb of the convex structures 191 formed on the first liblet sheet 1a-1#2 may be the same as or different from the pitch P_rb of the convex structures 191 formed on the second liblet sheet 1a-2#2. The extension direction of the convex structure 191 formed on the first riblet sheet 1a-1#2 may be the same as or different from the extension direction of the convex structure 191 formed on the second riblet sheet 1a-2#2.

[0052] As a third example, as shown in FIG. 5( c), a first liblet sheet 1a-1#3 on which a riblet structure RB including convex structures 191 extending in a first extension direction is formed, and a second liblet sheet 1a-2#3 on which a riblet structure RB including convex structures 191 extending in a second extension direction different from the first extension direction may be attached to the surface of an object OBJ. In other words, the surface of the object OBJ may include a first surface Os-1#3 on which the first liblet sheet 1a-1#3 is attached, and a second surface Os-2#3 on which the second liblet sheet 1a-2#3 is attached. Note that the pitch P_rb of the convex structures 191 formed on the first liblet sheet 1a-1#3 may be the same as or different from the pitch P_rb of the convex structures 191 formed on the second liblet sheet 1a-2#3. The height H_rb of the convex structure 191 formed on the first riblet sheet 1a-1#3 may be the same as or different from the height H_rb of the convex structure 191 formed on the second riblet sheet 1a-2#3. (1-3-2) Method for setting the characteristics of the riblet structure RB formed on the riblet sheet 1a Next, we will explain the method for setting the characteristics of the riblet structure RB formed on the riblet sheet 1a.

[0053] (1-3-2-1) First Example of Method for Setting the Characteristics of the Riblet Structure RB Formed on the Riblet Sheet 1a (First Characteristic Setting Method) In the first characteristic setting method, the characteristics of the riblet structure RB may be set to characteristics suitable for the purpose of reducing the resistance to a fluid of the surface portion of the surface of the object OBJ to which the riblet sheet 1a is attached. Specifically, the characteristics of the kth type of riblet structure RB formed on the kth riblet sheet 1a-k may be set to kth characteristics suitable for the purpose of reducing the resistance to a fluid of the kth surface Os-k to which the kth riblet sheet 1a-k is attached. For example, the pitch P_rb of the convex structures 191 formed on the kth riblet sheet 1a-k may be set to the kth pitch P_rb suitable for the purpose of reducing the resistance to a fluid of the kth surface Os-k. For example, the height H_rb of the convex structure 191 formed on the kth riblet sheet 1a-k may be set to a kth height H_rb suitable for the purpose of reducing the resistance of the kth surface Os-k to the fluid. For example, the extension direction of the convex structure 191 formed on the kth riblet sheet 1a-k may be set to a kth extension direction suitable for the purpose of reducing the resistance of the kth surface Os-k to the fluid. The kth extension direction may be, for example, a direction including a directional component along the direction of the streamline on the kth surface Os-k (that is, the direction of the fluid flow on the kth surface Os-k).

[0054] As one example, the characteristics of the first type of riblet structure RB formed on the first riblet sheet 1a-1 may be set to first characteristics suitable for the purpose of reducing the resistance to a fluid on a first surface Os-1 of the surface of the object OBJ to which the first riblet sheet 1a-1 is attached. For example, the characteristics of the second type of riblet structure RB formed on the second riblet sheet 1a-2 may be set to second characteristics suitable for the purpose of reducing the resistance to a fluid on a second surface Os-2 of the surface of the object OBJ to which the second riblet sheet 1a-2 is attached. In this case, the first riblet sheet 1a-1 may be attached to a first surface Os-1 that is set in advance on the surface of the object OBJ, and the second riblet sheet 1a-2 may be attached to a second surface Os-2 that is set in advance on the surface of the object OBJ.

[0055] Here, if a first riblet sheet 1a-1 is attached to each of the first surface Os-1 to the second surface Os-2, the resistance to the fluid of the first surface Os-1 may be appropriately reduced, while the resistance to the fluid of the second surface Os-2 may not be appropriately reduced. Similarly, if a second riblet sheet 1a-2 is attached to each of the first surface Os-1 to the second surface Os-2, the resistance to the fluid of the second surface Os-2 may be appropriately reduced, while the resistance to the fluid of the first surface Os-1 may not be appropriately reduced. However, in the first characteristic setting method, the first riblet sheet 1a-1 and the second riblet sheet 1a-2 are attached to the first surface Os-1 to the second surface Os-2, respectively. For this reason, the first riblet sheet 1a-1 appropriately reduces the resistance of the first surface Os-1 to the fluid, and the second riblet sheet 1a-2 also appropriately reduces the resistance of the second surface Os-2 to the fluid. Therefore, when the first characteristic setting method is used, an object OBJ to which the riblet sheet 1a is attached can appropriately enjoy the resistance reduction effect of the riblet sheet 1a (that is, the effect of reducing the resistance of the surface of the object OBJ to which the riblet sheet 1a is attached to the fluid).

[0056] (1-3-2-2) Second Example of Method for Setting the Characteristics of the riblet Structure RB Formed on the riblet Sheet 1a (Second Characteristic Setting Method) In the second characteristic setting method, the characteristics of the riblet structure RB may be set to characteristics suitable for the purpose of reducing the resistance of an object OBJ (i.e., a moving body) moving in a predetermined movement mode to a fluid. Specifically, the characteristics of the kth type of riblet structure RB formed on the kth riblet sheet 1a-k may be set to a kth characteristic suitable for the purpose of reducing the resistance of an object OBJ moving in the kth movement mode to a fluid. For example, the pitch P_rb of the convex structures 191 formed on the kth riblet sheet 1a-k may be set to a kth pitch P_rb suitable for the purpose of reducing the resistance of an object OBJ moving in the kth movement mode to a fluid. For example, the height H_rb of the convex structure 191 formed on the kth riblet sheet 1a-k may be set to the kth height H_rb suitable for the purpose of reducing the resistance of the object OBJ moving in the kth movement mode to the fluid. For example, the extension direction of the convex structure 191 formed on the kth riblet sheet 1a-k may be set to the kth extension direction suitable for the purpose of reducing the resistance of the object OBJ moving in the kth movement mode to the fluid.

[0057] When the second characteristic setting method is used, the object OBJ may be capable of moving in a first movement mode, a second movement mode different from the first movement mode, ..., an Nth movement mode different from the first to N-1th movement modes. In this case, the characteristic of the first type of riblet structure RB formed on the first riblet sheet 1a-1 may be set to a first characteristic suitable for the purpose of reducing the resistance of the object OBJ moving in the first movement mode to a fluid. The characteristic of the second type of riblet structure RB formed on the second riblet sheet 1a-2 may be set to a second characteristic suitable for the purpose of reducing the resistance of the object OBJ moving in the second movement mode to a fluid. The characteristic of the Nth type of riblet structure RB formed on the Nth riblet sheet 1a-N may be set to an Nth characteristic suitable for the purpose of reducing the resistance of the object OBJ moving in the Nth movement mode to a fluid. In other words, the characteristics of the kth type of riblet structure RB formed on the kth riblet sheet 1a-k may be set to kth characteristics suitable for the purpose of reducing the resistance of an object OBJ moving in a kth movement mode to a fluid. In this case, the kth riblet sheet 1a-k may be attached to a kth surface Os-k that is set in advance on the surface of the object OBJ. Alternatively, the kth riblet sheet 1a-k may be attached to any position on the surface of the object OBJ, and the surface of the object OBJ to which the kth riblet sheet 1a-k is attached may be used as the kth surface Os-k.

[0058] As one example, the object OBJ may be capable of moving in at least a first movement mode and a second movement mode different from the first movement mode. In this case, the characteristics of the first type of riblet structure RB formed on the first riblet sheet 1a-1 may be set to first characteristics suitable for the purpose of reducing the resistance of the object OBJ to a fluid when moving in the first movement mode. On the other hand, the characteristics of the second type of riblet structure RB formed on the second riblet sheet 1a-2 may be set to second characteristics suitable for the purpose of reducing the resistance of the object OBJ to a fluid when moving in the second movement mode. In this case, the first riblet sheet 1a-1 may be attached to a first surface Os-1 that is set in advance on the surface of the object OBJ, and the second riblet sheet 1a-2 may be attached to a second surface Os-2 that is set in advance on the surface of the object OBJ. Alternatively, the first libretto sheet 1a-1 and the second libretto sheet 1a-2 may each be attached to any position on the surface of the object OBJ, with the surface of the object OBJ to which the first libretto sheet 1a-1 is attached being used as the first surface Os-1, and the surface of the object OBJ to which the second libretto sheet 1a-2 is attached being used as the second surface Os-2.

[0059] Here, if a first riblet sheet 1a-1 is attached to each of the first surface Os-1 to the second surface Os-2, the resistance to the fluid of an object OBJ moving in the first movement mode is appropriately reduced, but the resistance to the fluid of an object OBJ moving in the second movement mode may not be appropriately reduced. Similarly, if a second riblet sheet 1a-2 is attached to each of the first surface Os-1 to the second surface Os-2, the resistance to the fluid of an object OBJ moving in the second movement mode is appropriately reduced, but the resistance to the fluid of an object OBJ moving in the first movement mode may not be appropriately reduced. However, in the second characteristic setting method, the first riblet sheet 1a-1 and the second riblet sheet 1a-2 are attached to the first surface Os-1 to the second surface Os-2, respectively. For this reason, the first riblet sheet 1a-1 appropriately reduces the resistance of the object OBJ moving in a first movement mode to the fluid, and the second riblet sheet 1a-2 also appropriately reduces the resistance of the object OBJ moving in a second movement mode. Therefore, when the second characteristic setting method is used, the resistance reduction effect of the riblet sheet 1a can be appropriately enjoyed in situations where the object OBJ to which the riblet sheet 1a is attached moves in various movement modes. In other words, the resistance reduction effect of the riblet sheet 1a can be appropriately enjoyed in situations where the movement mode of the object OBJ to which the riblet sheet 1a is attached changes.

[0060] The total area of ​​the surface of the object OBJ on the k-th surface Os-k to which the k-th libretto sheet 1a-k is attached may be set based on the frequency with which the object OBJ moves in the k-th movement mode during a predetermined period. In particular, the total area of ​​the surface of the object OBJ on the k-th surface Os-k to which the k-th libretto sheet 1a-k is attached and the total area of ​​the surface of the object OBJ on the m-th surface Os-m to which the m-th (m is a variable indicating an integer greater than or equal to 1 and less than or equal to a constant N and different from the variable k) libretto sheet 1a-m is attached may be set based on the frequency with which the object OBJ moves in the k-th movement mode during a predetermined period and the frequency with which the object OBJ moves in the m-th movement mode during a predetermined period. More specifically, the ratio between the total area of ​​the k-th surface Os-k and the total area of ​​the m-th surface Os-m may be set based on the ratio between the frequency with which the object OBJ moves in the k-th movement mode during a predetermined period and the frequency with which the object OBJ moves in the m-th movement mode during a predetermined period. As an example, the total area of ​​the kth surface Os-k and the total area of ​​the mth surface Os-m may be set so that the ratio between the total area of ​​the kth surface Os-k and the total area of ​​the mth surface Os-m is equal to or proportional to the ratio between the frequency at which the object OBJ moves in the kth movement pattern during a predetermined period and the frequency at which the object OBJ moves in the mth movement pattern during a predetermined period.

[0061] As an example, an example will be described in which the variable k is 1 and the variable m is 2. In this case, the total area of ​​the surface of the object OBJ on the first side Os-1 to which the first libretto sheet 1a-1 is attached and the total area of ​​the surface of the object OBJ on the second side Os-2 to which the second libretto sheet 1a-2 is attached may be set based on the frequency with which the object OBJ moves in a first movement manner during a predetermined period and the frequency with which the object OBJ moves in a second movement manner during the predetermined period. More specifically, the ratio between the total area of ​​the first side Os-1 and the total area of ​​the second side Os-2 may be set based on the ratio between the frequency with which the object OBJ moves in the first movement manner during a predetermined period and the frequency with which the object OBJ moves in the second movement manner during the predetermined period.

[0062] For example, the total area of ​​the first surface Os-1 and the total area of ​​the second surface Os-2 may be set so that the ratio between the total area of ​​the first surface Os-1 and the total area of ​​the second surface Os-2 is equal to or proportional to the ratio between the frequency at which the object OBJ moves in a first movement mode during a predetermined period and the frequency at which the object OBJ moves in a second movement mode during a predetermined period. In this case, if the frequency at which the object OBJ moves in the first movement mode during a predetermined period is higher than the frequency at which the object OBJ moves in the second movement mode during a predetermined period, the total area of ​​the first surface Os-1 may be larger than the total area of ​​the second surface Os-2. As a result, compared to when the total area of ​​the first surface Os-1 is smaller than the total area of ​​the second surface Os-2, the effect of reducing the resistance to the fluid of the object OBJ moving in the first movement mode, which has a higher movement frequency, is greater than the effect of reducing the resistance to the fluid of the object OBJ moving in the second movement mode, which has a lower movement frequency. Therefore, an object OBJ to which the riblet sheet 1a is attached can more effectively enjoy the resistance reduction effect of the riblet sheet 1a. On the other hand, if the frequency with which the object OBJ moves in the first movement mode during a predetermined period is lower than the frequency with which the object OBJ moves in the second movement mode during a predetermined period, the total area of ​​the first surface Os-1 may be smaller than the total area of ​​the second surface Os-2. As a result, compared to when the total area of ​​the first surface Os-1 is larger than the total area of ​​the second surface Os-2, the effect of reducing the resistance to the fluid of an object OBJ moving in the second movement mode, which has a higher movement frequency, is greater than the effect of reducing the resistance to the fluid of an object OBJ moving in the first movement mode, which has a lower movement frequency. Therefore, an object OBJ to which the riblet sheet 1a is attached can more effectively enjoy the resistance reduction effect of the riblet sheet 1a.

[0063] The movement mode of the object OBJ may include the movement speed of the object OBJ. In this case, the characteristics of the riblet structure RB may be set to characteristics suitable for the purpose of reducing the resistance of the object OBJ (i.e., the moving body) moving at a predetermined movement speed to a fluid. Specifically, the characteristics of the kth type of riblet structure RB formed on the kth riblet sheet 1a-k may be set to kth characteristics suitable for the purpose of reducing the resistance of the object OBJ moving at the kth movement speed to a fluid. For example, the object OBJ may be capable of moving at at least a first movement speed and a second movement speed different from the first movement speed. In this case, the characteristics of the first type of riblet structure RB formed on the first riblet sheet 1a-1 may be set to first characteristics suitable for the purpose of reducing the resistance of the object OBJ moving at the first movement speed to a fluid. On the other hand, the characteristics of the second type of riblet structure RB formed on the second riblet sheet 1a-2 may be set to second characteristics suitable for the purpose of reducing the resistance of an object OBJ moving at a second moving speed to a fluid. As a result, the first riblet sheet 1a-1 appropriately reduces the resistance of an object OBJ moving at a first moving speed, and the second riblet sheet 1a-2 also appropriately reduces the resistance of an object OBJ moving at a second moving speed to a fluid. Therefore, when the second characteristic setting method is used, the resistance reduction effect of the riblet sheet 1a can be appropriately enjoyed in situations where the object OBJ to which the riblet sheet 1a is attached moves at various moving speeds. In other words, the resistance reduction effect of the riblet sheet 1a can be appropriately enjoyed in situations where the moving speed of the object OBJ to which the riblet sheet 1a is attached changes.

[0064] When the movement mode of the object OBJ includes the movement speed of the object OBJ, the total area of ​​the surface of the object OBJ on the k-th surface Os-k to which the k-th riblet sheet 1a-k is attached may be set based on the frequency with which the object OBJ moves at the k-th movement speed during a predetermined period. For example, the total area of ​​the k-th surface Os-k and the total area of ​​the m-th surface Os-m may be set based on the frequency with which the object OBJ moves at the k-th movement speed during a predetermined period and the frequency with which the object OBJ moves at the m-th movement speed during a predetermined period. More specifically, the ratio between the total area of ​​the k-th surface Os-k and the total area of ​​the m-th surface Os-m may be set based on the ratio between the frequency with which the object OBJ moves at the k-th movement speed during a predetermined period and the frequency with which the object OBJ moves at the m-th movement speed during a predetermined period. As an example, the total area of ​​the kth surface Os-k and the total area of ​​the mth surface Os-m may be set so that the ratio between the total area of ​​the kth surface Os-k and the total area of ​​the mth surface Os-m is equal to or proportional to the ratio between the frequency at which the object OBJ moves at the kth moving speed during a predetermined period and the frequency at which the object OBJ moves at the mth moving speed during the predetermined period. In this case, if the frequency at which the object OBJ moves at the kth moving speed during a predetermined period is higher than the frequency at which the object OBJ moves at the mth moving speed during the predetermined period, the total area of ​​the kth surface Os-k may be larger than the total area of ​​the mth surface Os-m. On the other hand, if the frequency at which the object OBJ moves at the kth moving speed during a predetermined period is lower than the frequency at which the object OBJ moves at the mth moving speed during the predetermined period, the total area of ​​the kth surface Os-k may be smaller than the total area of ​​the mth surface Os-m. As a result, the object OBJ to which the riblet sheet 1a is attached can more effectively enjoy the resistance reduction effect of the riblet sheet 1a.

[0065] (1-3-2-3) Third Example of Method for Setting the Characteristics of the riblet Structure RB Formed on the riblet Sheet 1a (Third Characteristic Setting Method) In the third characteristic setting method, the characteristics of the riblet structure RB may be set to characteristics suitable for the purpose of reducing the resistance of an object OBJ (i.e., a moving body) moving in a predetermined movement environment to a fluid. Specifically, the characteristics of the kth type of riblet structure RB formed on the kth riblet sheet 1a-k may be set to a kth characteristic suitable for the purpose of reducing the resistance of an object OBJ moving in the kth movement environment to a fluid. For example, the pitch P_rb of the convex structures 191 formed on the kth riblet sheet 1a-k may be set to a kth pitch P_rb suitable for the purpose of reducing the resistance of an object OBJ moving in the kth movement environment to a fluid. For example, the height H_rb of the convex structure 191 formed on the kth riblet sheet 1a-k may be set to the kth height H_rb suitable for the purpose of reducing the resistance of the object OBJ moving in the kth movement environment to the fluid. For example, the extension direction of the convex structure 191 formed on the kth riblet sheet 1a-k may be set to the kth extension direction suitable for the purpose of reducing the resistance of the object OBJ moving in the kth movement environment to the fluid.

[0066] When the third characteristic setting method is used, the object OBJ may be movable in a first movement environment, a second movement environment different from the first movement environment, ..., an Nth movement environment different from the first to N-1th movement environments. In this case, the characteristic of the first type of riblet structure RB formed on the first riblet sheet 1a-1 may be set to a first characteristic suitable for reducing the resistance of the object OBJ to a fluid moving in the first movement environment. The characteristic of the second type of riblet structure RB formed on the second riblet sheet 1a-2 may be set to a second characteristic suitable for reducing the resistance of the object OBJ to a fluid moving in the second movement environment. The characteristic of the Nth type of riblet structure RB formed on the Nth riblet sheet 1a-N may be set to an Nth characteristic suitable for reducing the resistance of the object OBJ to a fluid moving in the Nth movement environment. In other words, the characteristics of the kth type of riblet structure RB formed on the kth riblet sheet 1a-k may be set to kth characteristics suitable for the purpose of reducing the resistance of an object OBJ to a fluid moving in the kth movement environment. In this case, the kth riblet sheet 1a-k may be attached to a kth surface Os-k that is set in advance on the surface of the object OBJ. Alternatively, the kth riblet sheet 1a-k may be attached to any position on the surface of the object OBJ, and the surface of the object OBJ to which the kth riblet sheet 1a-k is attached may be used as the kth surface Os-k.

[0067] As one example, the object OBJ may be capable of moving at least in a first movement environment and a second movement environment different from the first movement environment. In this case, the characteristics of the first type of riblet structure RB formed on the first riblet sheet 1a-1 may be set to first characteristics suitable for the purpose of reducing the resistance of the object OBJ to a fluid moving in the first movement environment. On the other hand, the characteristics of the second type of riblet structure RB formed on the second riblet sheet 1a-2 may be set to second characteristics suitable for the purpose of reducing the resistance of the object OBJ to a fluid moving in the second movement environment. In this case, the first riblet sheet 1a-1 may be attached to a first surface Os-1 that is set in advance on the surface of the object OBJ, and the second riblet sheet 1a-2 may be attached to a second surface Os-2 that is set in advance on the surface of the object OBJ. Alternatively, the first libretto sheet 1a-1 and the second libretto sheet 1a-2 may each be attached to any position on the surface of the object OBJ, with the surface of the object OBJ to which the first libretto sheet 1a-1 is attached being used as the first surface Os-1, and the surface of the object OBJ to which the second libretto sheet 1a-2 is attached being used as the second surface Os-2.

[0068] Here, if a first riblet sheet 1a-1 is attached to each of the first surface Os-1 to the second surface Os-2, the resistance to the fluid of the object OBJ moving in the first movement environment may be appropriately reduced, but the resistance to the fluid of the object OBJ moving in the second movement environment may not be appropriately reduced. Similarly, if a second riblet sheet 1a-2 is attached to each of the first surface Os-1 to the second surface Os-2, the resistance to the fluid of the object OBJ moving in the second movement environment may be appropriately reduced, but the resistance to the fluid of the object OBJ moving in the first movement environment may not be appropriately reduced. However, in the third characteristic setting method, the first riblet sheet 1a-1 and the second riblet sheet 1a-2 are attached to the first surface Os-1 to the second surface Os-2, respectively. For this reason, the first riblet sheet 1a-1 appropriately reduces the resistance of the object OBJ moving in a first movement environment to the fluid, and the second riblet sheet 1a-2 also appropriately reduces the resistance of the object OBJ moving in a second movement environment. Therefore, when the third characteristic setting method is used, the resistance reduction effect of the riblet sheet 1a can be appropriately enjoyed in situations where the object OBJ to which the riblet sheet 1a is attached moves in various movement environments. In other words, the resistance reduction effect of the riblet sheet 1a can be appropriately enjoyed in situations where the movement environment of the object OBJ to which the riblet sheet 1a is attached changes.

[0069] The total area of ​​the surface of the object OBJ on the k-th surface Os-k to which the k-th riblet sheet 1a-k is attached may be set based on the frequency with which the object OBJ moves in the k-th moving environment during a predetermined period. In particular, the total area of ​​the surface of the object OBJ on the k-th surface Os-k to which the k-th riblet sheet 1a-k is attached and the total area of ​​the surface of the object OBJ on the m-th surface Os-m to which the m-th riblet sheet 1a-m is attached may be set based on the frequency with which the object OBJ moves in the k-th moving environment during a predetermined period and the frequency with which the object OBJ moves in the m-th moving environment during a predetermined period. More specifically, the ratio between the total area of ​​the k-th surface Os-k and the total area of ​​the m-th surface Os-m may be set based on the ratio between the frequency with which the object OBJ moves in the k-th moving environment during a predetermined period and the frequency with which the object OBJ moves in the m-th moving environment during a predetermined period. As an example, the total area of ​​the kth surface Os-k and the total area of ​​the mth surface Os-m may be set so that the ratio between the total area of ​​the kth surface Os-k and the total area of ​​the mth surface Os-m is equal to or proportional to the ratio between the frequency with which the object OBJ moves in the kth moving environment during a specified period and the frequency with which the object OBJ moves in the mth moving environment during a specified period.

[0070] As an example, an example will be described in which the variable k is 1 and the variable m is 2. In this case, the total area of ​​the surface of the object OBJ on the first side Os-1 to which the first libretto sheet 1a-1 is attached and the total area of ​​the surface of the object OBJ on the second side Os-2 to which the second libretto sheet 1a-2 is attached may be set based on the frequency with which the object OBJ moves in the first moving environment during a predetermined period and the frequency with which the object OBJ moves in the second moving environment during the predetermined period. More specifically, the ratio between the total area of ​​the first side Os-1 and the total area of ​​the second side Os-2 may be set based on the ratio between the frequency with which the object OBJ moves in the first moving environment during a predetermined period and the frequency with which the object OBJ moves in the second moving environment during the predetermined period.

[0071] For example, the total area of ​​the first surface Os-1 and the total area of ​​the second surface Os-2 may be set so that the ratio between the total area of ​​the first surface Os-1 and the total area of ​​the second surface Os-2 is equal to or proportional to the ratio between the frequency with which the object OBJ moves in a first moving environment during a predetermined period and the frequency with which the object OBJ moves in a second moving environment during a predetermined period. In this case, if the frequency with which the object OBJ moves in the first moving environment during a predetermined period is higher than the frequency with which the object OBJ moves in a second moving environment during a predetermined period, the total area of ​​the first surface Os-1 may be larger than the total area of ​​the second surface Os-2. As a result, compared to when the total area of ​​the first surface Os-1 is smaller than the total area of ​​the second surface Os-2, the resistance reduction effect in the first moving environment in which the object OBJ moves with a relatively high frequency is higher than the resistance reduction effect in the second moving environment in which the object OBJ moves with a relatively low frequency. Therefore, an object OBJ to which the riblet sheet 1a is attached can more effectively enjoy the resistance reduction effect of the riblet sheet 1a. On the other hand, if the frequency with which the object OBJ moves in a first movement environment during a predetermined period is lower than the frequency with which the object OBJ moves in a second movement environment during a predetermined period, the total area of ​​the first surface Os-1 may be smaller than the total area of ​​the second surface Os-2. As a result, compared to when the total area of ​​the first surface Os-1 is larger than the total area of ​​the second surface Os-2, the resistance reduction effect in the second movement environment in which the object OBJ moves with a relatively high frequency is higher than the resistance reduction effect in the first movement environment in which the object OBJ moves with a relatively low frequency. Therefore, an object OBJ to which the riblet sheet 1a is attached can more effectively enjoy the resistance reduction effect of the riblet sheet 1a.

[0072] The environment in which the object OBJ moves may include the flow velocity of the fluid. In other words, the environment in which the object OBJ moves may include the flow velocity of the fluid flowing around the object OBJ moving through the fluid. The flow velocity of the fluid may mean the relative velocity of the fluid with respect to the object OBJ. In other words, the flow velocity of the fluid may mean a relative velocity that changes depending on the moving velocity of the object OBJ moving through the fluid. In addition, when the object OBJ is stationary in the fluid, the flow velocity of the fluid may mean the velocity of the fluid itself. In this way, even when the object OBJ is stationary in the fluid, the object OBJ may be considered to be moving relatively through the fluid as long as the fluid is flowing relative to the object OBJ.

[0073] When the movement environment includes a fluid flow velocity, the characteristics of the riblet structure RB may be set to characteristics suitable for the purpose of reducing the resistance of the object OBJ (i.e., the moving body) to a fluid flowing at a predetermined flow velocity. Specifically, the characteristics of the kth type of riblet structure RB formed on the kth riblet sheet 1a-k may be set to kth characteristics suitable for the purpose of reducing the resistance of the object OBJ to a fluid flowing at the kth flow velocity. For example, the fluid may flow at at least a first flow velocity and a second flow velocity different from the first flow velocity. In this case, the characteristics of the first type of riblet structure RB formed on the first riblet sheet 1a-1 may be set to first characteristics suitable for the purpose of reducing the resistance of the object OBJ to a fluid flowing at the first flow velocity. On the other hand, the characteristics of the second type of riblet structure RB formed on the second riblet sheet 1a-2 may be set to second characteristics suitable for the purpose of reducing the resistance of the object OBJ to a fluid flowing at a second flow velocity. As a result, the first riblet sheet 1a-1 appropriately reduces the resistance of the object OBJ to the fluid in a moving environment where the fluid flows at a first flow velocity, and the second riblet sheet 1a-2 also appropriately reduces the resistance of the object OBJ to the fluid in a moving environment where the fluid flows at a second flow velocity. Therefore, when the third characteristic setting method is used, in a situation where the flow velocity of the fluid flowing around the object OBJ to which the riblet sheet 1a is attached changes, the object OBJ to which the riblet sheet 1a is attached can appropriately enjoy the resistance reduction effect of the riblet sheet 1a.

[0074] When the environment in which the object OBJ moves includes a fluid flow velocity, the total area of ​​the surface of the object OBJ on the kth surface Os-k to which the kth riblet sheet 1a-k is attached may be set based on the frequency with which the object OBJ moves through a fluid flowing at the kth flow velocity during a predetermined period. For example, the total area of ​​the kth surface Os-k and the total area of ​​the mth surface Os-m may be set based on the frequency with which the object OBJ moves through a fluid flowing at the kth flow velocity during a predetermined period and the frequency with which the object OBJ moves through a fluid flowing at the mth flow velocity during a predetermined period. More specifically, the ratio between the total area of ​​the kth surface Os-k and the total area of ​​the mth surface Os-m may be set based on the ratio between the frequency with which the object OBJ moves through a fluid flowing at the kth flow velocity during a predetermined period and the frequency with which the object OBJ moves through a fluid flowing at the mth flow velocity during a predetermined period. As an example, the total area of ​​the kth surface Os-k and the total area of ​​the mth surface Os-m may be set so that the ratio between the total area of ​​the kth surface Os-k and the total area of ​​the mth surface Os-m is equal to or proportional to the ratio between the frequency at which an object OBJ moves through a fluid flowing at the kth flow velocity during a predetermined period and the frequency at which an object OBJ moves through a fluid flowing at the mth flow velocity during the predetermined period. In this case, if the frequency at which an object OBJ moves through a fluid flowing at the kth flow velocity during a predetermined period is higher than the frequency at which an object OBJ moves through a fluid flowing at the mth flow velocity during the predetermined period, the total area of ​​the kth surface Os-k may be larger than the total area of ​​the mth surface Os-m. On the other hand, if the frequency at which an object OBJ moves through a fluid flowing at the kth flow velocity during a predetermined period is lower than the frequency at which an object OBJ moves through a fluid flowing at the mth flow velocity during the predetermined period, the total area of ​​the kth surface Os-k may be smaller than the total area of ​​the mth surface Os-m. As a result, the object OBJ to which the riblet sheet 1a is attached can more effectively enjoy the resistance reduction effect of the riblet sheet 1a.

[0075] (1-3-2-4) Other examples of methods for setting the characteristics of the riblet structure RB formed on the riblet sheet 1a If the object OBJ is a railway vehicle, a first surface portion of the surface of the railway vehicle that is located on the left side of the direction of movement of the railway vehicle on the outbound journey may be located on the right side of the direction of movement of the railway vehicle on the return journey. Similarly, a second surface portion of the surface of the railway vehicle that is located on the right side of the direction of movement of the railway vehicle on the outbound journey may be located on the left side of the direction of movement of the railway vehicle on the return journey. In this case, the characteristics of the riblet structure RB formed on the riblet sheet 1a that is attached to the first surface portion may differ from the characteristics of the riblet structure RB formed on the riblet sheet 1a that is attached to the second surface portion.

[0076] For example, the frequency with which a railway vehicle travels around a right curve on the outbound journey may differ from the frequency with which the railway vehicle travels around a right curve on the return journey. Similarly, the frequency with which a railway vehicle travels around a left curve on the outbound journey may differ from the frequency with which the railway vehicle travels around a left curve on the return journey. Specifically, the frequency with which a railway vehicle travels around a right curve on the outbound journey may normally be the same as the frequency with which the railway vehicle travels around a left curve on the return journey. Similarly, the frequency with which a railway vehicle travels around a left curve on the outbound journey may normally be the same as the frequency with which the railway vehicle travels around a right curve on the return journey. For this reason, the characteristics of the riblet structure RB of the riblet sheet 1a attached to the first surface portion of the surface of the railway vehicle and the characteristics of the riblet structure RB of the riblet sheet 1a attached to the second surface portion of the surface of the railway vehicle may be set based on the frequency with which the railway vehicle travels around a right curve on each of the outbound and return journeys and the frequency with which the railway vehicle travels around a right curve on each of the outbound and return journeys. Furthermore, the ratio of the multiple types of libretto sheets 1a affixed to the first surface portion of the surface of the railway vehicle (for example, the ratio between the total area of ​​the above-mentioned first libretto sheets 1a-1 and the total area of ​​the second libretto sheets 1a-2) and the ratio of the multiple types of libretto sheets 1a affixed to the second surface portion of the surface of the railway vehicle may be set based on the frequency with which the railway vehicle travels around right curves on both the outbound and inbound journeys, and the frequency with which the railway vehicle travels around right curves on both the outbound and inbound journeys. As an example, the ratio of the multiple types of libretto sheets 1a affixed to the first surface portion of the surface of the railway vehicle and the ratio of the multiple types of libretto sheets 1a affixed to the second surface portion of the surface of the railway vehicle may be set to be different ratios.

[0077] Furthermore, if the object OBJ is a railway vehicle, the object OBJ may include multiple vehicles. In this case, the characteristics of the libretto structures RB of the multiple libretto sheets 1a affixed to each of the multiple vehicles may be set so that the characteristics of the libretto structure RB of the libretto sheet 1a affixed to one vehicle (e.g., the lead vehicle) differ from the characteristics of the libretto structures RB of the libretto sheets 1a affixed to other vehicles (e.g., the second vehicle). Furthermore, the ratio of the multiple types of libretto sheets 1a affixed to each vehicle may be set so that the ratio of the multiple types of libretto sheets 1a affixed to one vehicle (e.g., the lead vehicle) (e.g., the ratio between the total area of ​​the first libretto sheet 1a-1 and the total area of ​​the second libretto sheet 1a-2) differs from the ratio of the multiple types of libretto sheets 1a affixed to other vehicles (e.g., the second vehicle).

[0078] Note that multiple automobiles (especially trucks, which are large freight vehicles) traveling in a convoy on a road may also be considered as the object OBJ. In other words, the object OBJ may include multiple automobiles. In this case, similar to the case where a railroad car, which is an example of the object OBJ, includes multiple vehicles, the characteristics of the riblet structure RB of the riblet sheet 1a attached to each of the multiple automobiles included in the object OBJ may be set.

[0079] Furthermore, if the object OBJ is a vehicle, the object OBJ may be subjected to a crosswind in a direction intersecting the traveling direction of the object OBJ. In this case, the characteristics of the riblet structure RB of the riblet sheet 1a may be set taking the crosswind into consideration.

[0080] (1-3-3) Shapes of Multiple Libretto Sheets 1a The shapes (e.g., shapes in plan view) of multiple libretto sheets 1a, each having multiple types of libretto structures RB formed thereon, may be different from one another. In other words, the shape of each libretto sheet 1a may be a shape specific to the characteristics of the libretto structure RB formed on each libretto sheet 1a. For example, as shown in Figure 6, the shape of a first libretto sheet 1a-1 having a first type of libretto structure RB formed thereon, the shape of a second libretto sheet 1a-2 having a second type of libretto structure RB formed thereon, ..., the shape of a first libretto sheet 1a-N having an Nth type of libretto structure RB formed thereon may be different from one another. In other words, as shown in Figure 6, the shape of the first libretto sheet 1a-1 on which a first type of libretto structure RB is formed may be a first shape, the shape of the second libretto sheet 1a-2 on which a second type of libretto structure RB is formed may be a second shape different from the first shape, and so on, and the shape of the first libretto sheet 1a-N on which an Nth type of libretto structure RB is formed may be an Nth shape different from the first shape to the N-1th shape.

[0081] In this case, the multiple libretto sheets 1a, each having multiple types of libretto structures RB, can be distinguished from one another by their shapes. As a result, it is possible to prevent a libretto sheet 1a different from the first libretto sheet 1a-1 having the first type of libretto structure RB from being mistakenly attached to the first surface Os-1 to which the first libretto sheet 1a-1 having the first type of libretto structure RB should be attached. In other words, it is possible to prevent the wrong libretto sheet 1a from being attached.

[0082] (2) Libretto sheet 1b of the second embodiment Next, the libretto sheet 1 of the second embodiment will be described. In the following description, the libretto sheet 1 of the second embodiment will be referred to as the "libretto sheet 1b." In addition, in the following description, the libretto sheet 1b of the second embodiment will be described by mainly explaining the differences between the libretto sheet 1b of the second embodiment and the libretto sheet 1a of the first embodiment. Therefore, unless otherwise specified, the libretto sheet 1b of the second embodiment may have the same features as the libretto sheet 1a of the first embodiment.

[0083] (2-1) Overview of the Libretto Sheet 1b of the Second Embodiment The libretto sheet 1b of the second embodiment differs from the libretto sheet 1a of the first embodiment in that a single libretto sheet 1b may have multiple types of libretto structures RB with different characteristics formed therein. In the second embodiment, multiple libretto sheets 1b, each having multiple types of libretto structures RB with different characteristics formed therein, may be attached to the object OBJ. However, only one libretto sheet 1b, each having multiple types of libretto structures RB with different characteristics formed therein, may also be attached to the object OBJ. Furthermore, at least one libretto sheet 1b and at least one libretto sheet 1a may be attached to the object OBJ. Other features of the libretto sheet 1b may be the same as other features of the libretto sheet 1a.

[0084] 7, which is a plan view showing the riblet sheet 1b of the second embodiment, the riblet structure surface 130 of the riblet sheet 1b may include a partial structure surface 131 (first partial structure surface 131-1) on which a first type of riblet structure RB having a first characteristic is formed, a partial structure surface 131 (second partial structure surface 131-2) on which a second type of riblet structure RB having a second characteristic different from the first characteristic is formed, ..., a partial structure surface 131 (Nth partial structure surface 131-N) on which an Nth type of riblet structure RB having an Nth characteristic different from the first characteristic to the N-1th characteristic is formed. As an example, the riblet structure surface 130 of the riblet sheet 1b may include at least one first partial structure surface 131-1, at least one second partial structure surface 131-2, ..., at least one Nth partial structure surface 131-N. In other words, the riblet structure surface 130 of the riblet sheet 1b may include a single or multiple first partial structure surfaces 131-1, a single or multiple second partial structure surfaces 131-2, ..., a single or multiple Nth partial structure surfaces 131-N. Note that the constant N in the second embodiment (i.e., the number of partial structure surfaces 131) may be the same as or different from the constant N in the first embodiment (i.e., the number of types of riblet sheets 1a attached to the object OBJ). In other words, the riblet structure surface 130 of the riblet sheet 1b may be formed with a first type of riblet structure RB having a first characteristic, a second type of riblet structure RB having a second characteristic, ..., an Nth type of riblet structure RB having an Nth characteristic.

[0085] 7 shows an example in which the riblet structure surface 130 includes a first partial structure surface 131-1 on which a first type of riblet structure RB having a first characteristic is formed, and a second partial structure surface 131-2 on which a second type of riblet structure RB having a second characteristic is formed. In other words, FIG. 7 shows an example in which a first type of riblet structure RB having a first characteristic and a second type of riblet structure RB having a second characteristic are formed on the riblet structure surface 130. In the following explanation, for simplicity's sake, an example in which the riblet structure surface 130 includes a first partial structure surface 131-1 and a second partial structure surface 131-2 will be described. In other words, the following explanation will describe an example in which two types of riblet structures RB with different characteristics are formed in a single riblet sheet 1b. However, three or more types of riblet structures RB with different characteristics may be formed in a single riblet sheet 1b.

[0086] 7 also shows an example in which the riblet structure surface 130 includes a single first partial structure surface 131-1 and a single second partial structure surface 131-2. In other words, FIG. 7 shows an example in which the riblet structure surface 130 includes only a single first partial structure surface 131-1 and a single second partial structure surface 131-2. However, the riblet structure surface 130 may include a plurality of first partial structure surfaces 131-1. The riblet structure surface 130 may also include a plurality of second partial structure surfaces 131-2. Even in this case, the riblet structure surface 130 still includes one first partial structure surface 131-1 of the plurality of first partial structure surfaces 131-1 and one second partial structure surface 131-2 of the plurality of second partial structure surfaces 131-2. For example, the riblet structure surface 130 still includes a first partial structure surface 131-1 and a second partial structure surface 131-2 that are adjacent to each other.

[0087] The size of each partial structure surface 131 may be set to a desired size that allows at least a dozen to several tens of convex structures 191 to be arranged along a predetermined arrangement direction within each partial structure surface 131. As an example, the partial structure surface 131 may have a size of at least several tens to several hundred micrometers along the arrangement direction of the convex structures 191. However, the partial structure surface 131 may have a size of at least several millimeters to several meters along the arrangement direction of the convex structures 191.

[0088] In the second embodiment, as in the first embodiment, the characteristics of the riblet structure RB may include at least one of the pitch P_rb of the convex structure 191, the height H_rb of the convex structure 191, and the extension direction of the convex structure 191.

[0089] As a first example, as shown in FIG. 8( a), a riblet structure RB in which a plurality of convex structures 191 are arranged at a first pitch P_rb may be formed on the first partial structure surface 131-1. On the other hand, a riblet structure RB in which a plurality of convex structures 191 are arranged at a second pitch P_rb different from the first pitch P_rb may be formed on the second partial structure surface 131-2. The height H_rb of the convex structures 191 formed on the first partial structure surface 131-1 may be the same as or different from the height H_rb of the convex structures 191 formed on the second partial structure surface 131-2. The extension direction of the convex structures 191 formed on the first partial structure surface 131-1 may be the same as or different from the extension direction of the convex structures 191 formed on the second partial structure surface 131-2.

[0090] Furthermore, when the first partial structure surface 131-1 and the second partial structure surface 131-2 are aligned along the extension direction of the convex structures 191, at least one convex structure 191 formed on the first partial structure surface 131-1 may be connected to at least one convex structure formed on the second partial structure surface 131-2. In this case, the pitch P_rb of the convex structures 191 may gradually change near the boundary between the first partial structure surface 131-1 and the second partial structure surface 131-2 so that at least one convex structure 191 formed on the first partial structure surface 131-1 and at least one convex structure formed on the second partial structure surface 131-2 are smoothly connected. In this case, a sudden change in the pitch P_rb of the convex structures 191 at the boundary between the first partial structure surface 131-1 and the second partial structure surface 131-2 is prevented.

[0091] As a second example, as shown in FIG. 8( b), a riblet structure RB including convex structures 191 having a first height H_rb may be formed on the first partial structure surface 131-1. On the other hand, a riblet structure RB including convex structures 191 having a second height H_rb different from the first height H_rb may be formed on the second partial structure surface 131-2. The pitch P_rb of the convex structures 191 formed on the first partial structure surface 131-1 may be the same as or different from the pitch P_rb of the convex structures 191 formed on the second partial structure surface 131-2. The extension direction of the convex structures 191 formed on the first partial structure surface 131-1 may be the same as or different from the extension direction of the convex structures 191 formed on the second partial structure surface 131-2.

[0092] As described above, when the first partial structure surface 131-1 and the second partial structure surface 131-2 are aligned along the extension direction of the convex structure 191, at least one convex structure 191 formed on the first partial structure surface 131-1 may be connected to at least one convex structure formed on the second partial structure surface 131-2. In this case, the height H_rb of the convex structure 191 may gradually change near the boundary between the first partial structure surface 131-1 and the second partial structure surface 131-2 so that at least one convex structure 191 formed on the first partial structure surface 131-1 and at least one convex structure formed on the second partial structure surface 131-2 are smoothly connected. In this case, a sudden change in the height H_rb of the convex structure 191 at the boundary between the first partial structure surface 131-1 and the second partial structure surface 131-2 is prevented.

[0093] 8(c), a riblet structure RB including convex structures 191 extending in a first extension direction may be formed on the first partial structure surface 131-1. On the other hand, a riblet structure RB including convex structures 191 extending in a second extension direction different from the first extension direction may be formed on the second partial structure surface 131-2. Note that the pitch P_rb of the convex structures 191 formed on the first partial structure surface 131-1 may be the same as or different from the pitch P_rb of the convex structures 191 formed on the second partial structure surface 131-2. The height H_rb of the convex structures 191 formed on the first partial structure surface 131-1 may be the same as or different from the height H_rb of the convex structures 191 formed on the second partial structure surface 131-2. Note that, as described above, when the first partial structure surface 131-1 and the second partial structure surface 131-2 are aligned along the extension direction of the convex structures 191, the extension direction of the convex structures 191 may gradually change near the boundary between the first partial structure surface 131-1 and the second partial structure surface 131-2 so that at least one convex structure 191 formed on the first partial structure surface 131-1 and at least one convex structure formed on the second partial structure surface 131-2 are smoothly connected. In this case, a sudden change in the extension direction of the convex structures 191 at the boundary between the first partial structure surface 131-1 and the second partial structure surface 131-2 is prevented.

[0094] (2-2) Arrangement Pattern of Multiple Partial Structure Surfaces 131 in Libretto Sheet 1b In the libretto sheet 1b, the multiple partial structure surfaces 131 (e.g., first partial structure surfaces 131-1 and second partial structure surfaces 131-2) may be arranged in any arrangement pattern. For example, in the libretto sheet 1b, multiple first partial structure surfaces 131-1 and multiple second partial structure surfaces 131-2 may be arranged. For example, in the libretto sheet 1b, a single first partial structure surface 131-1 and a single second partial structure surface 131-2 may be arranged. For example, in the libretto sheet 1b, multiple first partial structure surfaces 131-1 and a single second partial structure surface 131-2 may be arranged. For example, in the libretto sheet 1b, a single first partial structure surface 131-1 and multiple second partial structure surfaces 131-2 may be arranged.

[0095] Within the libretto sheet 1b, the plurality of partial structure surfaces 131 (e.g., the first partial structure surface 131-1 and the second partial structure surface 131-2) may be arranged in a random arrangement pattern. Alternatively, within the libretto sheet 1b, the plurality of partial structure surfaces 131 (e.g., the first partial structure surface 131-1 and the second partial structure surface 131-2) may be arranged in a periodic arrangement pattern (in other words, a regular arrangement pattern).

[0096] An example of multiple partial structure surfaces 131 (specifically, multiple first partial structure surfaces 131-1 and multiple second partial structure surfaces 131-2) arranged in a periodic arrangement pattern is shown in Figures 9(a) to 9(d).

[0097] For example, as shown in Figures 9(a) to 9(c), each partial structure surface 131 may have a shape in which the direction along the riblet structure surface 130 is the longitudinal direction. The direction along the riblet structure surface 130 may be, for example, a direction along the XY plane. The direction along the riblet structure surface 130 may be, for example, a direction intersecting the height direction of the convex structures 191. Figures 9(a) and 9(c) each show an example in which each partial structure surface 131 has a shape in which the longitudinal direction is the Y-axis direction, which is the width direction of the riblet sheet 1b (i.e., the arrangement direction of the multiple convex structures 191). Figure 9(b) shows an example in which each partial structure surface 131 has a shape in which the longitudinal direction is the X-axis direction, which is the length direction of the riblet sheet 1b (i.e., the extension direction of the convex structures 191).

[0098] 9(b), when the longitudinal direction of the partial structure surface 131 is the same as the extension direction of the convex structure 191, the riblet sheet 1b may be attached to the object OBJ so that the longitudinal direction of the partial structure surface 131 (i.e., the extension direction of the convex structure 191) is a direction that includes a directional component along the direction of the streamlines at the surface portion of the surface of the object OBJ to which the riblet sheet 1b is attached. In this case, the object OBJ to which the riblet sheet 1b is attached can more appropriately enjoy the drag reduction effect compared to when the longitudinal direction of the partial structure surface 131 (i.e., the extension direction of the convex structure 191) intersects the direction of the streamlines.

[0099] Furthermore, as shown in Figures 9(a) and 9(b), the multiple partial structure surfaces 131 (specifically, the multiple first partial structure surfaces 131-1 and the multiple second partial structure surfaces 131-2) may be arranged so that the first partial structure surfaces 131-1 and the second partial structure surfaces 131-2 are alternately arranged along a direction intersecting the longitudinal direction of the partial structure surfaces 131. Note that an arrangement pattern in which the first partial structure surfaces 131-1 and the second partial structure surfaces 131-2 are alternately arranged along a direction may be referred to as a stripe pattern. Figure 9(a) shows an example in which the multiple partial structure surfaces 131 are arranged so that the first partial structure surfaces 131-1 and the second partial structure surfaces 131-2 are alternately arranged along the X-axis direction intersecting the longitudinal direction of the partial structure surfaces 131. Figure 9 (b) shows an example in which multiple partial structure surfaces 131 are arranged so that first partial structure surfaces 131-1 and second partial structure surfaces 131-2 are arranged alternately along the Y-axis direction that intersects the longitudinal direction of the partial structure surfaces 131.

[0100] Alternatively, as shown in FIG. 9( c), the multiple partial structure surfaces 131 (specifically, the multiple first partial structure surfaces 131-1 and the multiple second partial structure surfaces 131-2) may be arranged such that a predetermined number of first partial structure surfaces 131-1 and a predetermined number of second partial structure surfaces 131-2 are alternately arranged along a direction intersecting the longitudinal direction of the partial structure surface 131. Note that an arrangement pattern in which a predetermined number of first partial structure surfaces 131-1 and a predetermined number of second partial structure surfaces 131-2 are alternately arranged along a direction may also be referred to as a stripe pattern. FIG. 9( c) shows an example in which two first partial structure surfaces 131-1 and one second partial structure surface 131-2 are alternately arranged along a direction intersecting the longitudinal direction of the partial structure surface 131.

[0101] Alternatively, for example, as shown in Figure 9(d), the multiple partial structure surfaces 131 may be arranged so that the first partial structure surfaces 131-1 and the second partial structure surfaces 131-2 are alternately arranged along a first direction along the riblet structure surface 130 and a second direction along the riblet structure surface 130 and intersecting the first direction. An arrangement pattern in which the first partial structure surfaces 131-1 and the second partial structure surfaces 131-2 are alternately arranged along each of the first and second directions may be referred to as a grid pattern. Figure 9(c) shows an example in which the multiple partial structure surfaces 131 are arranged so that the first partial structure surfaces 131-1 and the second partial structure surfaces 131-2 are alternately arranged along each of the X-axis direction and the Y-axis direction.

[0102] 9(a) to 9(d) show an example in which the shape of the first partial structure surface 131-1 (specifically, the shape in a plan view) and the shape of the second partial structure surface 131-2 (specifically, the shape in a plan view) are the same. However, the shape of the first partial structure surface 131-1 (specifically, the shape in a plan view) and the shape of the second partial structure surface 131-2 (specifically, the shape in a plan view) may be different.

[0103] (2-3) Method for Setting the Characteristics of the riblet structure RB Formed on the riblet sheet 1b In the second embodiment, the characteristics of the riblet structure RB formed on the riblet sheet 1b may also be set using a method similar to the method for setting the characteristics of the riblet structure RB formed on the riblet sheet 1a in the first embodiment. Below, a method for setting the characteristics of the riblet structure RB formed on the riblet sheet 1b will be described.

[0104] (2-3-1) First Example of Method for Setting the Characteristics of the riblet Structure RB Formed on the riblet Sheet 1b (First Characteristic Setting Method) In the first characteristic setting method, the characteristics of the kth type of riblet structure RB formed on the kth (note that, as described in the first embodiment, k is a variable indicating an integer greater than or equal to 1 and less than or equal to the constant N) partial structure surface 131-k of the riblet sheet 1b may be set to kth characteristics suitable for the purpose of reducing the resistance to a fluid of the kth object surface, which is a part of the surface of the object OBJ. For example, the pitch P_rb of the convex structures 191 formed on the kth partial structure surface 131-k of the riblet sheet 1b may be set to a kth pitch P_rb suitable for the purpose of reducing the resistance to a fluid of the kth object surface of the object OBJ. For example, the height H_rb of the convex structures 191 formed on the kth partial structure surface 131-k of the riblet sheet 1b may be set to a kth height H_rb suitable for the purpose of reducing the resistance to a fluid of the kth object surface of the object OBJ. For example, the extension direction of the convex structure 191 formed on the k-th partial structure surface 131-k of the riblet sheet 1b may be set to a k-th extension direction suitable for the purpose of reducing the resistance of the k-th object surface of the object OBJ to the fluid. The k-th extension direction may be, for example, a direction including a directional component along the direction of the streamline on the k-th object surface (i.e., the direction of the fluid flow on the k-th object surface).

[0105] As one example, the characteristics of the first type of riblet structure RB formed on the first partial structure surface 131-1 may be set to first characteristics suitable for the purpose of reducing the resistance to a fluid of a first object surface that is a part of the surface of the object OBJ. For example, the characteristics of the second type of riblet structure RB formed on the second partial structure surface 131-2 may be set to second characteristics suitable for the purpose of reducing the resistance to a fluid of a second object surface that is a part of the surface of the object OBJ and different from the first object surface. In this case, at least one riblet sheet 1b on which both the first and second types of riblet structures RB are formed may be attached to each of the first and second object surfaces of the object OBJ.

[0106] Here, if a riblet sheet 1b in which a first type of riblet structure RB is formed but a second type of riblet structure RB is not formed (that is, including the first partial structure surface 131-1 but not the second partial structure surface 131-2) is attached to each of the first object surface and the second object surface of the object OBJ, the resistance to the fluid on the first object surface may be appropriately reduced, but the resistance to the fluid on the second object surface may not be appropriately reduced. Similarly, if a riblet sheet 1b in which a second type of riblet structure RB is formed but a first type of riblet structure RB is not formed (that is, including the second partial structure surface 131-2 but not the first partial structure surface 131-2) is attached to each of the first object surface and the second object surface of the object OBJ, the resistance to the fluid on the second object surface may be appropriately reduced, but the resistance to the fluid on the first object surface may not be appropriately reduced. However, in the first characteristic setting method, a riblet sheet 1b having both the first and second types of riblet structures RB formed thereon (i.e., including both the first partial structure surface 131-1 and the second partial structure surface 131-2) is attached to each of the first and second object surfaces. As a result, the resistance of the first object surface to the fluid is appropriately reduced by the first type of riblet structure RB, and the resistance of the second object surface to the fluid is also appropriately reduced by the second type of riblet structure RB. Therefore, when the first characteristic setting method is used, the object OBJ to which the riblet sheet 1b is attached can appropriately enjoy the resistance reduction effect of the riblet sheet 1b (i.e., the effect of reducing the resistance of the surface of the object OBJ to which the riblet sheet 1b is attached to the fluid).

[0107] (2-3-2) Second Example of Method for Setting the Characteristics of the riblet Structure RB Formed on the riblet Sheet 1b (Second Characteristic Setting Method) In the second characteristic setting method, the characteristics of the kth type of riblet structure RB formed on the kth partial structure surface 131-k of the riblet sheet 1b may be set to a kth characteristic suitable for the purpose of reducing the resistance of an object OBJ moving in a kth movement mode to a fluid. For example, the pitch P_rb of the convex structures 191 formed on the kth partial structure surface 131-k of the riblet sheet 1b may be set to a kth pitch P_rb suitable for the purpose of reducing the resistance of an object OBJ moving in a kth movement mode to a fluid. For example, the height H_rb of the convex structures 191 formed on the kth partial structure surface 131-k of the riblet sheet 1b may be set to a kth height H_rb suitable for the purpose of reducing the resistance of an object OBJ moving in a kth movement mode to a fluid. For example, the extension direction of the convex structure 191 formed on the kth partial structure surface 131-k of the riblet sheet 1b may be set to the kth extension direction suitable for the purpose of reducing the resistance of an object OBJ moving in the kth movement mode to the fluid.

[0108] When the second characteristic setting method is used, the object OBJ may be capable of moving in each of a first movement mode, a second movement mode different from the first movement mode, ..., and an Nth movement mode different from the first to N-1th movement modes. In this case, the characteristics of the first type of riblet structure RB formed on the first partial structure surface 131-1 may be set to a first characteristic suitable for the purpose of reducing the resistance of the object OBJ moving in the first movement mode to a fluid. The characteristics of the second type of riblet structure RB formed on the second partial structure surface 131-2 may be set to a second characteristic suitable for the purpose of reducing the resistance of the object OBJ moving in the second movement mode to a fluid. The characteristics of the Nth type of riblet structure RB formed on the Nth partial structure surface 131-N may be set to an Nth characteristic suitable for the purpose of reducing the resistance of the object OBJ moving in the Nth movement mode to a fluid.

[0109] As an example, the object OBJ may be capable of moving in at least a first movement mode and a second movement mode different from the first movement mode. In this case, the characteristics of the first type of riblet structure RB formed on the first partial structure surface 131-1 may be set to first characteristics suitable for the purpose of reducing the resistance of the object OBJ moving in the first movement mode to a fluid. On the other hand, the characteristics of the second type of riblet structure RB formed on the second partial structure surface 131-2 may be set to second characteristics suitable for the purpose of reducing the resistance of the object OBJ moving in the second movement mode to a fluid.

[0110] Here, if a riblet sheet 1b having a first type of riblet structure RB formed thereon but not a second type of riblet structure RB formed thereon (that is, including the first partial structure surface 131-1 but not the second partial structure surface 131-2) is attached to the surface of an object OBJ, the resistance to the fluid of the object OBJ moving in the first movement mode will be appropriately reduced, but the resistance to the fluid of the object OBJ moving in the second movement mode may not be appropriately reduced. Similarly, if a riblet sheet 1b having a second type of riblet structure RB formed thereon but not a first type of riblet structure RB formed thereon (that is, including the second partial structure surface 131-2 but not the first partial structure surface 131-1) is attached to the surface of an object OBJ, the resistance to the fluid of the object OBJ moving in the second movement mode will be appropriately reduced, but the resistance to the fluid of the object OBJ moving in the first movement mode may not be appropriately reduced. However, in the second characteristic setting method, a riblet sheet 1b having both the first and second types of riblet structures RB formed thereon (i.e., including both the first partial structure surface 131-1 and the second partial structure surface 131-2) is attached to the surface of an object OBJ. As a result, the first type of riblet structure RB appropriately reduces the resistance of the object OBJ moving in a first movement mode to a fluid, and the second type of riblet structure RB also appropriately reduces the resistance of the object OBJ moving in a second movement mode to a fluid. Therefore, when the second characteristic setting method is used, the resistance reduction effect of the riblet sheet 1b can be appropriately enjoyed in situations where the object OBJ to which the riblet sheet 1b is attached moves in various movement modes. In other words, the resistance reduction effect of the riblet sheet 1b can be appropriately enjoyed in situations where the movement mode of the object OBJ to which the riblet sheet 1b is attached changes.

[0111] The total area of ​​the surface of the riblet sheet 1b of the k-th partial structure surface 131-k on which the k-th type of riblet structure RB is formed may be set based on the frequency with which the object OBJ moves in the k-th movement mode during a predetermined period. In particular, the total area of ​​the surface of the riblet sheet 1b of the k-th partial structure surface 131-k on which the k-th type of riblet structure RB is formed and the total area of ​​the surface of the riblet sheet 1b of the m-th partial structure surface 131-m on which the m-th type of riblet structure RB (m is a variable indicating an integer greater than or equal to 1 and less than or equal to the constant N and different from the variable k, as described in the first embodiment) is formed may be set based on the frequency with which the object OBJ moves in the k-th movement mode during a predetermined period and the frequency with which the object OBJ moves in the m-th movement mode during a predetermined period. More specifically, the ratio between the total area of ​​the k-th partial structure surface 131-k and the total area of ​​the m-th partial structure surface 131-m may be set based on the ratio between the frequency at which the object OBJ moves in the k-th movement mode during a predetermined period and the frequency at which the object OBJ moves in the m-th movement mode during a predetermined period. As an example, the total area of ​​the k-th partial structure surface 131-k and the total area of ​​the m-th partial structure surface 131-m may be set so that the ratio between the total area of ​​the k-th partial structure surface 131-k and the total area of ​​the m-th partial structure surface 131-m is equal to or proportional to the ratio between the frequency at which the object OBJ moves in the k-th movement mode during a predetermined period and the frequency at which the object OBJ moves in the m-th movement mode during a predetermined period.

[0112] As an example, an example will be described in which the variable k is 1 and the variable m is 2. In this case, the total area of ​​the surface of the riblet sheet 1b of the first partial structure surface 131-1 on which the first type of riblet structure RB is formed and the total area of ​​the surface of the riblet sheet 1b of the second partial structure surface 131-2 on which the second type of riblet structure RB is formed may be set based on the frequency with which the object OBJ moves in a first movement mode during a predetermined period and the frequency with which the object OBJ moves in a second movement mode during the predetermined period. More specifically, the ratio between the total area of ​​the first partial structure surface 131-1 and the total area of ​​the second partial structure surface 131-2 may be set based on the ratio between the frequency with which the object OBJ moves in the first movement mode during a predetermined period and the frequency with which the object OBJ moves in the second movement mode during the predetermined period.

[0113] For example, the total area of ​​the first partial structure surface 131-1 and the total area of ​​the second partial structure surface 131-2 may be set so that the ratio between the total area of ​​the first partial structure surface 131-1 and the total area of ​​the second partial structure surface 131-2 is equal to or proportional to the ratio between the frequency at which the object OBJ moves in a first movement manner during a predetermined period and the frequency at which the object OBJ moves in a second movement manner during the predetermined period. In this case, if the frequency at which the object OBJ moves in the first movement manner during a predetermined period is higher than the frequency at which the object OBJ moves in the second movement manner during the predetermined period, the total area of ​​the first partial structure surface 131-1 may be larger than the total area of ​​the second partial structure surface 131-2. As a result, compared to when the total area of ​​the first partial structure surface 131-1 is smaller than the total area of ​​the second partial structure surface 131-2, the effect of reducing the resistance of an object OBJ moving in the first movement mode, which has a high frequency of movement, to a fluid is greater than the effect of reducing the resistance of an object OBJ moving in the second movement mode, which has a low frequency of movement. Therefore, an object OBJ to which the riblet sheet 1b is attached can more effectively enjoy the resistance reduction effect of the riblet sheet 1b. On the other hand, if the frequency with which the object OBJ moves in the first movement mode during a predetermined period is lower than the frequency with which the object OBJ moves in the second movement mode during a predetermined period, the total area of ​​the first partial structure surface 131-1 may be smaller than the total area of ​​the second partial structure surface 131-2. As a result, compared to when the total area of ​​the first partial structure surface 131-1 is larger than the total area of ​​the second partial structure surface 131-2, the effect of reducing the resistance to the fluid of the object OBJ moving in the second movement mode with a higher frequency of movement is greater than the effect of reducing the resistance to the fluid of the object OBJ moving in the first movement mode with a lower frequency of movement. Therefore, the object OBJ to which the riblet sheet 1b is attached can more effectively enjoy the resistance reduction effect of the riblet sheet 1b.

[0114] In the second embodiment, as in the first embodiment, the movement mode of the object OBJ may include the movement speed of the object OBJ. In this case, the characteristics of the kth type of riblet structure RB formed on the kth partial structure surface 131-k of the riblet sheet 1b may be set to kth characteristics suitable for reducing the resistance of the object OBJ moving at the kth movement speed to a fluid. For example, the object OBJ may be capable of moving at at least a first movement speed and a second movement speed different from the first movement speed. In this case, the characteristics of the first type of riblet structure RB formed on the first partial structure surface 131-1 may be set to first characteristics suitable for reducing the resistance of the object OBJ moving at the first movement speed to a fluid. On the other hand, the characteristics of the second type of riblet structure RB formed on the second partial structure surface 131-2 may be set to second characteristics suitable for reducing the resistance of the object OBJ moving at the second movement speed to a fluid. As a result, the first type of riblet structure RB appropriately reduces the resistance of an object OBJ moving at a first moving speed to a fluid, and the second type of riblet structure RB also appropriately reduces the resistance of an object OBJ moving at a second moving speed. Therefore, when the second characteristic setting method is used, the resistance reduction effect of the riblet sheet 1b can be appropriately enjoyed in situations where the object OBJ to which the riblet sheet 1b is attached moves at various moving speeds. In other words, the resistance reduction effect of the riblet sheet 1b can be appropriately enjoyed in situations where the moving speed of the object OBJ to which the riblet sheet 1b is attached changes.

[0115] When the movement mode of the object OBJ includes the movement speed of the object OBJ, the total area of ​​the kth partial structure surface 131-k on the surface of the riblet sheet 1b on which the kth type of riblet structure RB is formed may be set based on the frequency with which the object OBJ moves at the kth movement speed during a predetermined period. For example, the total area of ​​the kth partial structure surface 131-k and the total area of ​​the mth partial structure surface 131-m may be set based on the frequency with which the object OBJ moves at the kth movement speed during a predetermined period and the frequency with which the object OBJ moves at the mth movement speed during a predetermined period. More specifically, the ratio between the total area of ​​the kth partial structure surface 131-k and the total area of ​​the mth partial structure surface 131-m may be set based on the ratio between the frequency with which the object OBJ moves at the kth movement speed during a predetermined period and the frequency with which the object OBJ moves at the mth movement speed during a predetermined period. As an example, the total area of ​​the kth partial structure surface 131-k and the total area of ​​the mth partial structure surface 131-m may be set so that the ratio between the total area of ​​the kth partial structure surface 131-k and the total area of ​​the mth partial structure surface 131-m is equal to or proportional to the ratio between the frequency at which the object OBJ moves at the kth movement speed during a predetermined period and the frequency at which the object OBJ moves at the mth movement speed during the predetermined period. In this case, if the frequency at which the object OBJ moves at the kth movement speed during a predetermined period is higher than the frequency at which the object OBJ moves at the mth movement speed during the predetermined period, the total area of ​​the kth partial structure surface 131-k may be larger than the total area of ​​the mth partial structure surface 131-m. On the other hand, if the frequency at which the object OBJ moves at the kth movement speed during a predetermined period is lower than the frequency at which the object OBJ moves at the mth movement speed during the predetermined period, the total area of ​​the kth partial structure surface 131-k may be smaller than the total area of ​​the mth partial structure surface 131-m. As a result, the object OBJ to which the riblet sheet 1b is attached can more effectively enjoy the resistance reduction effect of the riblet sheet 1b.

[0116] (2-3-3) Third Example of Method for Setting the Characteristics of the Riblet Structure RB Formed on the Riblet Sheet 1b (Third Characteristic Setting Method) In the third characteristic setting method, the characteristics of the kth type of riblet structure RB formed on the kth partial structure surface 131-k of the riblet sheet 1b may be set to a kth characteristic suitable for the purpose of reducing the resistance of an object OBJ moving in a kth movement environment to a fluid. For example, the pitch P_rb of the convex structures 191 formed on the kth partial structure surface 131-k of the riblet sheet 1b may be set to a kth pitch P_rb suitable for the purpose of reducing the resistance of an object OBJ moving in a kth movement environment to a fluid. For example, the height H_rb of the convex structures 191 formed on the kth partial structure surface 131-k of the riblet sheet 1b may be set to a kth height H_rb suitable for the purpose of reducing the resistance of an object OBJ moving in a kth movement environment to a fluid. For example, the extension direction of the convex structure 191 formed on the kth partial structure surface 131-k of the riblet sheet 1b may be set to the kth extension direction suitable for the purpose of reducing the resistance of an object OBJ moving in the kth movement environment to the fluid.

[0117] When the third characteristic setting method is used, the object OBJ may be movable in each of a first movement environment, a second movement environment different from the first movement environment, ..., and an Nth movement environment different from the first to N-1th movement environments. In this case, the characteristics of the first type of riblet structure RB formed on the first partial structure surface 131-1 may be set to a first characteristic suitable for reducing the resistance of the object OBJ moving in the first movement environment to a fluid. The characteristics of the second type of riblet structure RB formed on the second partial structure surface 131-2 may be set to a second characteristic suitable for reducing the resistance of the object OBJ moving in the second movement environment to a fluid. The characteristics of the Nth type of riblet structure RB formed on the Nth partial structure surface 131-N may be set to an Nth characteristic suitable for reducing the resistance of the object OBJ moving in the Nth movement environment to a fluid.

[0118] As an example, the object OBJ may be movable at least in a first movement environment and a second movement environment different from the first movement environment. In this case, the characteristics of the first type of riblet structure RB formed on the first partial structure surface 131-1 may be set to first characteristics suitable for reducing the resistance of the object OBJ moving in the first movement environment to a fluid. On the other hand, the characteristics of the second type of riblet structure RB formed on the second partial structure surface 131-2 may be set to second characteristics suitable for reducing the resistance of the object OBJ moving in the second movement environment to a fluid.

[0119] Here, if a riblet sheet 1b having a first type of riblet structure RB formed thereon but not a second type of riblet structure RB (i.e., including the first partial structure surface 131-1 but not the second partial structure surface 131-2) is attached to the surface of an object OBJ, the resistance to the fluid of the object OBJ moving in the first movement environment may be appropriately reduced, but the resistance to the fluid of the object OBJ moving in the second movement environment may not be appropriately reduced. Similarly, if a riblet sheet 1b having a second type of riblet structure RB formed thereon but not a first type of riblet structure RB (i.e., including the second partial structure surface 131-2 but not the first partial structure surface 131-1) is attached to the surface of an object OBJ, the resistance to the fluid of the object OBJ moving in the second movement environment may be appropriately reduced, but the resistance to the fluid of the object OBJ moving in the first movement environment may not be appropriately reduced. However, in the third characteristic setting method, a riblet sheet 1b having both the first and second types of riblet structures RB formed thereon (i.e., including both the first partial structure surface 131-1 and the second partial structure surface 131-2) is attached to the surface of an object OBJ. As a result, the first type of riblet structure RB appropriately reduces the resistance of the object OBJ moving in a first movement environment to a fluid, and the second type of riblet structure RB also appropriately reduces the resistance of the object OBJ moving in a second movement environment to a fluid. Therefore, when the third characteristic setting method is used, the resistance reduction effect of the riblet sheet 1b can be appropriately enjoyed in situations where the object OBJ to which the riblet sheet 1b is attached moves in various movement environments. In other words, the resistance reduction effect of the riblet sheet 1b can be appropriately enjoyed in situations where the movement environment of the object OBJ to which the riblet sheet 1b is attached changes.

[0120] The total area of ​​the surface of the riblet sheet 1b of the k-th partial structure surface 131-k on which the k-th type of riblet structure RB is formed may be set based on the frequency with which the object OBJ moves in the k-th moving environment during a predetermined period. In particular, the total area of ​​the surface of the riblet sheet 1b of the k-th partial structure surface 131-k on which the k-th type of riblet structure RB is formed and the total area of ​​the surface of the riblet sheet 1b of the m-th partial structure surface 131-m on which the m-th type of riblet structure RB is formed may be set based on the frequency with which the object OBJ moves in the k-th moving environment during a predetermined period and the frequency with which the object OBJ moves in the m-th moving environment during a predetermined period. More specifically, the ratio between the total area of ​​the k-th partial structure surface 131-k and the total area of ​​the m-th partial structure surface 131-m may be set based on the ratio between the frequency with which the object OBJ moves in the k-th moving environment during a predetermined period and the frequency with which the object OBJ moves in the m-th moving environment during a predetermined period. As an example, the total area of ​​the kth partial structure surface 131-k and the total area of ​​the mth partial structure surface 131-m may be set so that the ratio between the total area of ​​the kth partial structure surface 131-k and the total area of ​​the mth partial structure surface 131-m is equal to or proportional to the ratio between the frequency at which the object OBJ moves in the kth moving environment during a specified period and the frequency at which the object OBJ moves in the mth moving environment during a specified period.

[0121] As an example, an example will be described in which the variable k is 1 and the variable m is 2. In this case, the total area of ​​the surface of the libretto sheet 1b of the first partial structure surface 131-1 on which the first type of riblet structure RB is formed and the total area of ​​the surface of the libretto sheet 1b of the second partial structure surface 131-2 on which the second type of riblet structure RB is formed may be set based on the frequency with which the object OBJ moves in a first moving environment during a predetermined period and the frequency with which the object OBJ moves in a second moving environment during the predetermined period. More specifically, the ratio between the total area of ​​the first partial structure surface 131-1 and the total area of ​​the second partial structure surface 131-2 may be set based on the ratio between the frequency with which the object OBJ moves in a first moving environment during a predetermined period and the frequency with which the object OBJ moves in a second moving environment during the predetermined period.

[0122] For example, the total area of ​​the first partial structure surface 131-1 and the total area of ​​the second partial structure surface 131-2 may be set so that the ratio between the total area of ​​the first partial structure surface 131-1 and the total area of ​​the second partial structure surface 131-2 is equal to or proportional to the ratio between the frequency with which the object OBJ moves in a first moving environment during a predetermined period and the frequency with which the object OBJ moves in a second moving environment during a predetermined period. In this case, if the frequency with which the object OBJ moves in the first moving environment during a predetermined period is higher than the frequency with which the object OBJ moves in the second moving environment during a predetermined period, the total area of ​​the first partial structure surface 131-1 may be larger than the total area of ​​the second partial structure surface 131-2. As a result, compared to when the total area of ​​the first partial structure surface 131-1 is smaller than the total area of ​​the second partial structure surface 131-2, the resistance reduction effect in the first movement environment in which the object OBJ moves relatively frequently is higher than the resistance reduction effect in the second movement environment in which the object OBJ moves relatively less frequently. Therefore, the object OBJ to which the riblet sheet 1b is attached can more effectively enjoy the resistance reduction effect of the riblet sheet 1b. On the other hand, if the frequency with which the object OBJ moves in the first movement environment during a predetermined period is lower than the frequency with which the object OBJ moves in the second movement environment during a predetermined period, the total area of ​​the first partial structure surface 131-1 may be smaller than the total area of ​​the second partial structure surface 131-2. As a result, compared to when the total area of ​​the first partial structure surface 131-1 is larger than the total area of ​​the second partial structure surface 131-2, the resistance reduction effect in the second movement environment in which the object OBJ moves with a relatively high frequency is higher than the resistance reduction effect in the first movement environment in which the object OBJ moves with a relatively low frequency. Therefore, the object OBJ to which the riblet sheet 1b is attached can more effectively enjoy the resistance reduction effect of the riblet sheet 1b.

[0123] In the second embodiment, as in the first embodiment, the environment in which the object OBJ moves may include the flow velocity of the fluid. In this case, the characteristics of the kth type of riblet structure RB formed on the kth partial structure surface 131-k of the riblet sheet 1b may be set to kth characteristics suitable for reducing the resistance of the object OBJ to a fluid flowing at the kth flow velocity. For example, the fluid may flow at at least a first flow velocity and a second flow velocity different from the first flow velocity. In this case, the characteristics of the first type of riblet structure RB formed on the first partial structure surface 131-1 may be set to first characteristics suitable for reducing the resistance of the object OBJ to a fluid flowing at the first flow velocity. On the other hand, the characteristics of the second type of riblet structure RB formed on the second partial structure surface 131-2 may be set to second characteristics suitable for reducing the resistance of the object OBJ to a fluid flowing at a second flow velocity. As a result, the first type of riblet structure RB appropriately reduces the resistance of the object OBJ to the fluid in a moving environment in which the fluid flows at a first flow velocity, and the second type of riblet structure RB appropriately reduces the resistance of the object OBJ to the fluid in a moving environment in which the fluid flows at a second flow velocity. Therefore, when the third characteristic setting method is used, the object OBJ to which the riblet sheet 1b is attached can appropriately enjoy the resistance reduction effect of the riblet sheet 1b in a situation in which the flow velocity of the fluid flowing around the object OBJ to which the riblet sheet 1b is attached changes.

[0124] When the environment in which the object OBJ moves includes the flow speed of a fluid, the total area of ​​the surface of the riblet sheet 1b of the kth partial structure surface 131-k on which the kth type of riblet structure RB is formed may be set based on the frequency with which the object OBJ moves through a fluid flowing at the kth flow speed during a predetermined period. For example, the total area of ​​the kth partial structure surface 131-k and the total area of ​​the mth partial structure surface 131-m may be set based on the frequency with which the object OBJ moves through a fluid flowing at the kth flow speed during a predetermined period and the frequency with which the object OBJ moves through a fluid flowing at the mth flow speed during a predetermined period. More specifically, the ratio between the total area of ​​the kth partial structure surface 131-k and the total area of ​​the mth partial structure surface 131-m may be set based on the ratio between the frequency with which the object OBJ moves through a fluid flowing at the kth flow speed during a predetermined period and the frequency with which the object OBJ moves through a fluid flowing at the mth flow speed during a predetermined period. As an example, the total area of ​​the kth partial structure surface 131-k and the total area of ​​the mth partial structure surface 131-m may be set so that the ratio between the total area of ​​the kth partial structure surface 131-k and the total area of ​​the mth partial structure surface 131-m is equal to or proportional to the ratio between the frequency at which the object OBJ moves through a fluid flowing at the kth flow velocity during a predetermined period and the frequency at which the object OBJ moves through a fluid flowing at the mth flow velocity during a predetermined period. In this case, if the frequency at which the object OBJ moves through a fluid flowing at the kth flow velocity during a predetermined period is higher than the frequency at which the object OBJ moves through a fluid flowing at the mth flow velocity during a predetermined period, the total area of ​​the kth partial structure surface 131-k may be larger than the total area of ​​the mth partial structure surface 131-m. On the other hand, if the frequency with which the object OBJ moves through a fluid flowing at the kth flow velocity during a predetermined period is lower than the frequency with which the object OBJ moves through a fluid flowing at the mth flow velocity during a predetermined period, the total area of ​​the kth partial structure surface 131-k may be smaller than the total area of ​​the mth partial structure surface 131-m. As a result, the object OBJ to which the riblet sheet 1b is attached can more effectively enjoy the resistance reduction effect of the riblet sheet 1b.

[0125] (3) Manufacturing Apparatus 2 for Manufacturing Libretto Sheet 1 Next, a manufacturing apparatus 2 for manufacturing the libretto sheet 1 (i.e., at least one of the libretto sheets 1a and 1b) will be described. The manufacturing apparatus 2 may be a processing apparatus 2a capable of performing removal processing. The manufacturing apparatus 2 may be an imprint molding apparatus 2b capable of performing imprint molding using a mold 3b. For this reason, the processing apparatus 2a and the imprint molding apparatus 2b, each of which can function as the manufacturing apparatus 2, will be described in order below.

[0126] (3-1) Configuration of Processing Apparatus 2a First, the configuration of processing apparatus 2a will be described with reference to Fig. 10 and Fig. 11. Fig. 10 is a cross-sectional view showing a schematic configuration of processing apparatus 2a. Fig. 11 is a system configuration diagram showing the system configuration of processing apparatus 2a.

[0127] As shown in Figures 10 and 11, the processing apparatus 2a includes a processing device 21a, a processing light source 22a, and a control device 23a. At least a portion of the processing device 21a is housed in the internal space of a housing 24a. The internal space of the housing 24a may or may not be purged with a purge gas such as nitrogen gas. The internal space of the housing 24a may or may not be evacuated. However, the processing device 21a does not have to be housed in the internal space of the housing 24a. In other words, the processing apparatus 2a does not have to include a housing 24a that houses the processing device 21a.

[0128] The processing device 21a is capable of processing the material sheet 100, which is the material for the riblet sheet 1, under the control of the control device 23a. The material sheet 100 includes at least a coating layer 12 on which a riblet structure RB is not formed. The material sheet 100 may include an adhesive layer 11 in addition to the coating layer 12. The processing device 21a performs a removal process to remove a portion of the material sheet 100. By performing the removal process, the processing device 21a forms a riblet structure RB in the material sheet 100. As a result, a riblet sheet 1 on which a riblet structure RB is formed is manufactured.

[0129] The processing device 21a irradiates the material sheet 100 with processing light EL to process the material sheet 100. The processing light EL may be any type of light as long as it can process the material sheet 100 when irradiated thereto. The processing light EL may include pulsed light (e.g., pulsed light having an emission time of picoseconds or less). Alternatively, the processing light EL may not include pulsed light. In other words, the processing light EL may be continuous light. The processing light EL is supplied to the processing device 21a from a processing light source 22a that generates the processing light EL via a light propagation member (e.g., at least one of an optical fiber and a mirror) (not shown). The processing device 21a irradiates the material sheet 100 with the processing light EL supplied from the processing light source 22a.

[0130] In order to process the material sheet 100, the processing device 21a includes a processing head 211a, a head drive system 212a, a stage 213a, and a stage drive system 214a.

[0131] The processing head 211a irradiates the processing light EL from the processing light source 22a onto the material sheet 100. The processing head 211a may, for example, focus the processing light EL on the surface of the material sheet 100. The processing head 211a may, for example, control the optical characteristics of the processing light EL. Examples of the optical characteristics of the processing light EL include at least one of the intensity of the processing light EL, changes in the intensity of the processing light EL over time, the focusing position of the processing light EL, the angle of incidence of the processing light EL with respect to the material sheet 100, the shape of the processing light EL within an optical plane intersecting the optical axis of the processing optical system 111, the intensity distribution of the processing light EL within the optical plane, and the pulse number of the processing light EL (when the processing light EL is pulsed light).

[0132] The head drive system 212a moves the processing head 211a along at least one of the X-axis, Y-axis, and Z-axis directions under the control of the control device 23a. The head drive system 212a may also move the processing head 211a along at least one of the θX-axis, θY-axis, and θZ-axis directions in addition to or instead of at least one of the X-axis, Y-axis, and Z-axis directions. When the processing head 211a moves, the positional relationship between the stage 213a (and further, the material sheet 100 placed on the stage 213a) and the processing head 211a changes. Furthermore, when the positional relationship between the stage 213a, the material sheet 100, and the processing head 211a changes, the irradiation position of the processing light EL on the material sheet 100 changes.

[0133] The material sheet 100 is placed on the stage 213a. The stage 213a does not have to hold the material sheet 100 placed on the stage 213a. In other words, the stage 213a does not have to apply a holding force to the material sheet 100 placed on the stage 213a to hold the material sheet 100. Alternatively, the stage 213a may hold the material sheet 100 placed on the stage 213a. In other words, the stage 213a may apply a holding force to the material sheet 100 placed on the stage 213a to hold the material sheet 100. For example, the stage 213a may hold the material sheet 100 by vacuum suction and / or electrostatic suction. Alternatively, a jig for holding the material sheet 100 may hold the material sheet 100, and the stage 213a may hold the jig holding the material sheet 100.

[0134] The stage drive system 214a moves the stage 213a under the control of the control device 23a. Specifically, the stage drive system 214a moves the stage 213a relative to the processing head 211a. For example, under the control of the control device 23a, the stage drive system 214a may move the stage 213a along at least one of the X-axis direction, the Y-axis direction, the Z-axis direction, the θX direction, the θY direction, and the θZ direction. Note that moving the stage 213a along at least one of the θX direction, the θY direction, and the θZ direction may be considered equivalent to rotating (or rotationally moving) the stage 213a around at least one of the X-axis, the Y-axis, and the Z-axis. When the stage 213a moves, the positional relationship between the stage 213a (and further the material sheet 100 placed on the stage 213a) and the processing head 211a changes. Furthermore, when the positional relationship between the stage 213a, the material sheet 100, and the processing head 211a changes, the irradiation position of the processing light EL on the material sheet 100 changes.

[0135] The control device 23a controls the operation of the processing device 2a. For example, the control device 23a may generate processing control information for processing the material sheet 100 and control the processing device 21a based on the processing control information so that the material sheet 100 is processed in accordance with the generated processing control information. In other words, the control device 23a may control the processing of the material sheet 100.

[0136] The control device 23a may include, for example, an arithmetic device and a storage device. The arithmetic device may include, for example, at least one of a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit). The control device 23a functions as a device that controls the operation of the machining device 2a by the arithmetic device executing a computer program. This computer program is a computer program for causing the control device 23a (e.g., the arithmetic device) to perform (i.e., execute) the operations to be performed by the control device 23a, which will be described later. In other words, this computer program is a computer program for causing the control device 23a to function so as to cause the machining device 2a to perform the operations to be performed later. The computer program executed by the arithmetic device may be recorded in a storage device (i.e., a recording medium) included in the control device 23a, or may be recorded in any storage medium (e.g., a hard disk or semiconductor memory) built into or externally attachable to the control device 23a. Alternatively, the computing device may download the computer program to be executed from a device external to the control device 23a via a network interface.

[0137] (3-2) Configuration of Imprint Molding Apparatus 2b (3-2-1) First Imprint Molding Apparatus 2b#1 First, the first imprint molding apparatus 2b#1 will be described with reference to Fig. 12. Fig. 12 is a perspective view that schematically shows the structure of the first imprint molding apparatus 2b#1.

[0138] As shown in Figure 12, the first imprint molding apparatus 2b#1 includes a flat mold 3b#1, which is an example of a mold 3b, a feed roller 21b#1, a table 22b#1, a heater 23b#1, and a recovery roller (winding roller) 24b#1.

[0139] The flat mold 3b#1 is a mold 3b having a flat plate shape. Specifically, the flat mold 3b#1 is a flat member having a molding surface 30b#1 that is a flat surface. The molding surface 30b#1 is a surface on which the mold structure MB is formed. The mold structure MB is a structure for transferring the riblet structure RB to the material sheet 100. In this case, the first imprint molding apparatus 2b#1 may transfer (i.e., form) the riblet structure RB on the surface of the material sheet 100 by pressing the molding surface 30b#1 against the material sheet 100.

[0140] The feed roller 21b#1 is a cylindrical member around which the material sheet 100 is wrapped. Like the riblet sheet 1, the material sheet 100 is a sheet-like member extending in the longitudinal direction. The feed roller 21b#1 rotates around its central axis to sequentially supply the material sheet 100 onto the table 22b#1. The mold structure MB formed on the molding surface 30b#1 of the flat mold 3b#1 is then pressed against the material sheet 100 supplied onto the table 22b#1. As a result, the riblet structure RB corresponding to the mold structure MB is transferred to the material sheet 100. The table 22b#1 may heat the material sheet 100 to facilitate the transfer of the riblet structure RB to the material sheet 100. In other words, the table 22b#1 may soften the material sheet 100 by heating it. Each time the riblet structure RB is transferred to the material sheet 100, the recovery roller 24b#1 rotates around its central axis to recover (in other words, wind up) the material sheet 100 to which the riblet structure RB has been transferred. As a result, the material sheet 100 to which the riblet structure RB has been transferred is wound around the recovery roller 24b#1. Furthermore, at the same time that the recovery roller 24b#1 recovers the material sheet 100, the feed roller 21b#1 supplies a new material sheet 100 to the table 22b#1.

[0141] The first imprint molding apparatus 2b#1 alternately repeats the pressing of the flat mold 3b#1 against the material sheet 100 and the supply and collection of the material sheet 100. For example, the first imprint molding apparatus 2b#1 may use a feed roller 21b#1 to supply a first portion of the material sheet 100 onto the table 22b#1. The first imprint molding apparatus 2b#1 may then press the mold structure MB formed on the molding surface 30b#1 of the flat mold 3b#1 against the first portion of the material sheet 100 supplied on the table 22b#1. As a result, a riblet structure RB corresponding to the mold structure MB is transferred to the first portion of the material sheet 100. The first imprint molding apparatus 2b#1 may then use the collection roller 24b#1 to collect the first portion of the material sheet 100 to which the riblet structure RB has been transferred, and may use the feed roller 21b#1 to supply a second portion of the material sheet 100 adjacent to the first portion along the longitudinal direction onto the table 22b#1. The first imprint molding apparatus 2b#1 may then press the mold structure MB formed on the molding surface 30b#1 of the flat mold 3b#1 against the second portion of the material sheet 100 supplied onto the table 22b#1. As a result, the riblet structure RB corresponding to the mold structure MB is transferred to the second portion of the material sheet 100. Thereafter, the first imprint molding apparatus 2b#1 may repeat the same operation. As a result, the riblet structure RB is formed on the material sheet 100 extending along the longitudinal direction (the X-axis direction in the example shown in FIG. 12). In other words, a riblet sheet 1 extending along the longitudinal direction (the X-axis direction in the example shown in FIG. 12) is produced.

[0142] In the example described above, the first imprint molding apparatus 2b#1 transfers the riblet structure RB to the material sheet 100 by pressing the flat die 3b#1 against the material sheet 100 to deform the material sheet 100. However, the first imprint molding apparatus 2b#1 may also form the riblet structure RB by applying a photocurable resin onto the material sheet 100 and irradiating the photocurable resin with curing light while pressing the flat die 3b#1 against the applied photocurable resin.

[0143] (3-2-2) Second Imprint Molding Apparatus 2b#2 Next, the second imprint molding apparatus 2b#2 will be described with reference to Fig. 13. Fig. 13 is a perspective view that schematically shows the structure of the second imprint molding apparatus 2b#2.

[0144] As shown in Figure 13, the second imprint molding apparatus 2b#2 includes a roller mold 3b#2, which is an example of a mold 3b, a feed roller 21b#2, an auxiliary roller 22b#2, an auxiliary roller 23b#2, and a recovery roller (winding roller) 24b#2.

[0145] The roller die 3b#2 is a cylindrical die 3b. Specifically, the roller die 3b#2 is a cylindrical member that can function as a roller that can rotate around a central axis. In this case, the curved outer peripheral surface (i.e., side surface) of the cylindrical member is used as the molding surface 30b#2 of the roller die 3b#2. Therefore, the die structure MB is formed on the curved outer peripheral surface of the cylindrical member used as the roller die 3b#2.

[0146] The feed roller 21b#2 is a cylindrical member around which the material sheet 100 is wound. The feed roller 21b#2 rotates about its central axis to sequentially supply the material sheet 100. The material sheet 100 supplied by the feed roller 21b#2 is sent to the recovery roller 24b#2 by auxiliary rollers 22b#2 and 23b#2, each of which can rotate about its central axis. Here, the roller die 3b#2 is pressed against the surface of the material sheet 100 sent out by the auxiliary rollers 22b#2 and 23b#2. More specifically, the material sheet 100 sent out by the auxiliary rollers 22b#2 and 23b#2 is sandwiched between the roller die 3b#2 and the auxiliary rollers 22b#2 and 23b#2, respectively, and at this time, the mold structure MB formed on the molding surface 30b#2 of the roller die 3b#2 is pressed against the surface of the material sheet 100. As a result, a riblet structure RB corresponding to the mold structure MB is transferred to the material sheet 100. At least one of the auxiliary rollers 22b#2 and 23b#2 may heat the material sheet 100 to make it easier to transfer the riblet structure RB to the material sheet 100. In other words, at least one of the auxiliary rollers 22b#2 and 23b#2 may soften the material sheet 100 by heating it. The material sheet 100 to which the riblet structure RB has been transferred is collected (i.e., wound up) by the collection roller 24b#2, which can rotate around its central axis. In other words, the material sheet 100 to which the riblet structure RB has been transferred is wound around the collection roller 24b#2.

[0147] In the example described above, the second imprint molding apparatus 2b#2 transfers the riblet structure RB by pressing the roller die 3b#2 against the material sheet 100 to deform the material sheet 100. However, the second imprint molding apparatus 2b#2 may also form the riblet structure RB by applying a photocurable resin onto the material sheet 100 and irradiating the applied photocurable resin with curing light while pressing the roller die 3b#2 against the photocurable resin.

[0148] (4) Modifications In the above description, the riblet structure RB includes a plurality of convex structures 191 extending along a predetermined extension direction. However, the riblet structure RB may include a plurality of convex structures that do not extend along the predetermined extension direction, in addition to or instead of the convex structures 191. For example, the riblet structure RB may include a plurality of convex structures having a cylindrical or prismatic shape. For example, the riblet structure RB may include a plurality of convex structures having a conical or pyramidal shape.

[0149] When the riblet structure RB includes a plurality of convex structures that do not extend along a predetermined extension direction, the plurality of convex structures may include at least two convex structures arranged along any direction along the XY plane. In particular, the plurality of convex structures may include at least two convex structures arranged along any first direction along the XY plane, and at least two convex structures arranged along any second direction along the XY plane and different from the first direction. For example, the plurality of convex structures may include at least two convex structures arranged along the X-axis direction, and at least two convex structures arranged along the Y-axis direction. For example, the plurality of convex structures may include a plurality of convex structures arranged in a matrix.

[0150] In the above description, the riblet sheet 1 (i.e., at least one of the riblet sheets 1a and 1b) has a riblet structure RB formed thereon. However, any structure having any shape may be formed on the riblet sheet 1 in addition to or instead of the riblet structure RB. Any structure having any shape may be formed on the riblet sheet 1 as an alternative structure to the riblet structure RB. One example of the optional structure is a structure that generates vortices in the flow of a fluid on the surface of the object OBJ to which the riblet sheet 1 is attached. Another example of the optional structure is a structure that imparts hydrophobicity to the surface of the object OBJ to which the riblet sheet 1 is attached. Another example of the optional structure is a regularly or irregularly formed fine texture structure on the order of micrometers or nanometers (typically, a concave-convex structure including a mountain structure and a groove structure). The fine texture structure may include at least one of a shark skin structure and a dimple structure that has the function of reducing resistance caused by a fluid (gas and / or liquid). The fine texture structure may include a lotus leaf surface structure having at least one of a liquid-repellent function and a self-cleaning function (e.g., having the lotus effect). The fine texture structure may include at least one of a micro-projection structure having a liquid transport function (see U.S. Patent Publication No. 2017 / 0044002), a concave-convex structure having a lyophilic function, a convex-convex structure having an antifouling function, a moth-eye structure having at least one of a reflectance-reducing function and a liquid-repellent function, a convex-convex structure that exhibits structural color by intensifying only light of a specific wavelength through interference, a pillar array structure having an adhesive function utilizing van der Waals forces, a convex-convex structure having an aerodynamic noise reduction function, a honeycomb structure having a droplet collection function, a convex-convex structure that improves adhesion with a layer formed on the surface, a convex-convex structure for reducing frictional resistance, etc. The fine texture structure may also include a convex-convex structure having a soundproofing function, a sound-absorbing function, or a sound-deadening function.

[0151] In this case, as described in the first embodiment, a plurality of riblet sheets 1 a, each having a plurality of types of structures with different characteristics formed thereon, may be attached to the surface of the object OBJ. As described in the second embodiment, a single riblet sheet 1 b may have a plurality of types of structures with different characteristics formed thereon.

[0152] (5) Supplementary Notes The following supplementary notes are further disclosed regarding the embodiments described above. [Supplementary Note 1] A moving body capable of moving through a fluid, the surface of the moving body including: a first surface to which a first sheet member having a first riblet structure formed thereon is attached; and a second surface to which a second sheet member having a second riblet structure formed thereon is attached, and the characteristics of the first riblet structure are different from the characteristics of the second riblet structure. [Supplementary Note 2] The moving body described in Supplementary Note 1, wherein the characteristics of the first riblet structure are set to first characteristics suitable for the purpose of reducing the resistance of the first surface to the fluid, and the characteristics of the second riblet structure are set to second characteristics suitable for the purpose of reducing the resistance of the second surface to the fluid. [Supplementary Note 3] The moving body according to Supplementary Note 1 or 2, wherein the moving body is capable of moving in at least one of a first movement mode and a second movement mode, the characteristic of the first riblet structure is set to a third characteristic suitable for the purpose of reducing resistance to the fluid of the moving body moving in the first movement mode, and the characteristic of the second riblet structure is set to a fourth characteristic suitable for the purpose of reducing resistance to the fluid of the moving body moving in the second movement mode different from the first movement mode. [Supplementary Note 4] The moving body according to Supplementary Note 3, wherein each of the first and second movement modes includes a movement speed of the moving body. [Supplementary Note 5] The moving body according to Supplementary Note 3 or 4, wherein the moving body is capable of moving at a first moving speed and a second moving speed, the third characteristic is set to a characteristic suitable for the purpose of reducing the resistance of the moving body moving at the first moving speed to the fluid, the fourth characteristic is set to a characteristic suitable for the purpose of reducing the resistance of the moving body moving at the second moving speed to the fluid, and the frequency at which the moving body moves at the first moving speed in a first period is higher than the frequency at which the moving body moves at the second moving speed in the first period.[Supplementary Note 6] The moving body according to Supplementary Note 5, wherein at least one of the first sheet members is attached to the first surface, at least one of the second sheet members is attached to the second surface, and a total area of ​​the first surfaces on the surface of the moving body is larger than a total area of ​​the second surfaces on the surface of the moving body. [Supplementary Note 7] The moving body according to any one of Supplementary Notes 3 to 6, wherein at least one of the first sheet members is attached to the first surface, at least one of the second sheet members is attached to the second surface, and the total area of ​​the first surfaces on the surface of the moving body and the total area of ​​the second surfaces on the surface of the moving body are set based on a frequency at which the moving body moves in the first movement mode and a frequency at which the moving body moves in the second movement mode. [Supplementary Note 8] The moving body according to any one of Supplements 3 to 7, wherein at least one first sheet member is attached to the first surface, and at least one second sheet member is attached to the second surface, and a ratio of a total area of ​​the first surface on the surface of the moving body to a total area of ​​the second surface on the surface of the moving body is set based on a ratio of a frequency at which the moving body moves in the first movement mode to a frequency at which the moving body moves in the second movement mode. [Supplementary Note 9] The moving body according to any one of Supplements 1 to 8, wherein a characteristic of the first riblet structure is set to a fifth characteristic suitable for the purpose of reducing resistance to the fluid of the moving body moving in a first movement environment, and a characteristic of the second riblet structure is set to a sixth characteristic suitable for the purpose of reducing resistance to the fluid of the moving body moving in a second movement environment different from the first movement environment. [Supplementary Note 10] The moving body according to Supplementary Note 9, wherein each of the first and second movement environments includes a flow velocity of the fluid.[Supplementary Note 11] The moving body according to Supplementary Note 9 or 10, wherein the flow velocity of the fluid includes a first flow velocity and a second flow velocity, the fifth characteristic is set to a characteristic suitable for the purpose of reducing resistance of the moving body to the fluid at the first flow velocity, the sixth characteristic is set to a characteristic suitable for the purpose of reducing resistance of the moving body to the fluid at the second flow velocity, and a frequency at which the fluid is at the first flow velocity in a second period is higher than a frequency at which the fluid is at the second flow velocity in the second period. [Supplementary Note 12] The moving body according to Supplementary Note 11, wherein at least one first sheet member is attached to the first surface, and at least one second sheet member is attached to the second surface, and a total area of ​​the first surfaces on the surface of the moving body is greater than a total area of ​​the second surfaces on the surface of the moving body. [Supplementary Note 13] The moving body according to any one of Supplementary Notes 9 to 12, wherein at least one first sheet member is attached to the first surface, and at least one second sheet member is attached to the second surface, and a total area of ​​the first surface on the surface of the moving body and a total area of ​​the second surface on the surface of the moving body are set based on a frequency at which the moving body moves in the first moving environment and a frequency at which the moving body moves in the second moving environment. [Supplementary Note 14] The moving body according to any one of Supplementary Notes 9 to 13, wherein at least one first sheet member is attached to the first surface, and at least one second sheet member is attached to the second surface, and a ratio between the total area of ​​the first surface on the surface of the moving body and the total area of ​​the second surface on the surface of the moving body is set based on a ratio between a frequency at which the moving body moves in the first moving environment and a frequency at which the moving body moves in the second moving environment.[Supplementary Note 15] The moving body described in any one of Supplementary Notes 1 to 14, wherein the first riblet structure includes a structure in which a plurality of first convex structures extending along a first direction along the first surface and protruding along a second direction intersecting the first direction are formed so as to be aligned along a third direction along the first surface and intersecting the first and second directions, and the second riblet structure includes a structure in which a plurality of second convex structures extending along a fourth direction along the second surface and protruding along a fifth direction intersecting the fourth direction are formed so as to be aligned along the second surface and intersecting the fourth and fifth directions. [Supplementary Note 16] The moving body according to Supplementary Note 15, wherein the characteristics of the first riblet structure include at least one of the pitch of the plurality of first convex structures, the height of each of the plurality of first convex structures, and the direction in which each of the plurality of first convex structures extends, and the characteristics of the second riblet structure include at least one of the pitch of the plurality of second convex structures, the height of each of the plurality of second convex structures, and the direction in which each of the plurality of second convex structures extends. [Supplementary Note 17] The moving body according to Supplementary Note 15 or 16, wherein the pitch of the plurality of first convex structures is different from the pitch of the plurality of second convex structures. [Supplementary Note 18] The moving body according to any one of Supplements 15 to 17, wherein the height of each of the plurality of first convex structures is different from the height of each of the plurality of second convex structures. [Supplementary Note 19] The moving body according to any one of Supplements 15 to 18, wherein the direction in which each of the plurality of first convex structures extends is different from the direction in which each of the plurality of second convex structures extends. [Supplementary Note 20] The moving body according to any one of Supplements 1 to 19, wherein the shape of the first sheet member is different from the shape of the second sheet member. [Supplementary Note 21] A sheet member, wherein the surface of the sheet member includes a first surface on which a first riblet structure is formed and a second surface on which a second riblet structure is formed, and wherein characteristics of the first riblet structure are different from characteristics of the second riblet structure.[Supplementary Note 22] The sheet member according to Supplementary Note 21, wherein the sheet member is attachable to at least a portion of the surface of a moving body that can move through a fluid, and the characteristic of the first riblet structure is set to a first characteristic suitable for the purpose of reducing the resistance of a first face of the surface of the moving body to the fluid, and the characteristic of the second riblet structure is set to a second characteristic suitable for the purpose of reducing the resistance of a second face of the surface of the moving body to the fluid. [Supplementary Note 23] The sheet member according to Supplementary Note 21 or 22, wherein the sheet member is attachable to at least a portion of the surface of a moving body that can move through a fluid in at least one of a first movement mode and a second movement mode, and the characteristic of the first riblet structure is set to a third characteristic suitable for the purpose of reducing the resistance of the moving body that moves in a first movement mode to the fluid, and the characteristic of the second riblet structure is set to a fourth characteristic suitable for the purpose of reducing the resistance of the moving body that moves in a second movement mode different from the first movement mode to the fluid. [Supplementary Note 24] The sheet member according to Supplementary Note 23, wherein each of the first and second movement modes includes a movement speed of the moving body. [Supplementary Note 25] The moving body is capable of moving at a first movement speed and a second movement speed, the third characteristic is set to a characteristic suitable for the purpose of reducing resistance of the moving body moving at the first movement speed to the fluid, and the fourth characteristic is set to a characteristic suitable for the purpose of reducing resistance of the moving body moving at the second movement speed to the fluid, and the frequency at which the moving body moves at the first movement speed in a first period is higher than the frequency at which the moving body moves at the second movement speed in the first period. [Supplementary Note 26] The sheet member according to Supplementary Note 25, wherein a total area of ​​the first faces on a surface of the sheet member is greater than a total area of ​​the second faces on a surface of the sheet member. [Appendix 27] The sheet member described in any one of Appendices 23 to 26, wherein the total area of ​​the first surface on the surface of the sheet member and the total area of ​​the second surface on the surface of the sheet member are set based on the frequency at which the moving body moves in the first movement mode and the frequency at which the moving body moves in the second movement mode.[Supplementary Note 28] The sheet member according to any one of Supplements 23 to 27, wherein a ratio between the total area of ​​the first faces on the surface of the sheet member and the total area of ​​the second faces on the surface of the sheet member is set based on a ratio between a frequency at which the moving body moves in the first movement mode and a frequency at which the moving body moves in the second movement mode. [Supplementary Note 29] The sheet member according to any one of Supplements 21 to 28, wherein the sheet member can be attached to at least a portion of a surface of a moving body that can move through a fluid, and wherein a characteristic of the first riblet structure is set to a fifth characteristic suitable for reducing resistance to the fluid of the moving body that moves in a first movement environment, and a characteristic of the second riblet structure is set to a sixth characteristic suitable for reducing resistance to the fluid of the moving body that moves in a second movement environment different from the first movement environment. [Supplementary Note 30] The sheet member according to Supplementary Note 29, wherein each of the first and second movement environments includes a flow velocity of the fluid. [Supplementary Note 31] The sheet member according to Supplementary Note 29 or 30, wherein the flow velocity of the fluid includes a first flow velocity and a second flow velocity, the fifth characteristic is set to a characteristic suitable for reducing resistance of the moving body to the fluid at the first flow velocity, the sixth characteristic is set to a characteristic suitable for reducing resistance of the moving body to the fluid at the second flow velocity, and a frequency at which the fluid has the first flow velocity in a second period is higher than a frequency at which the fluid has the second flow velocity in the second period. [Supplementary Note 32] The sheet member according to Supplementary Note 31, wherein a total area of ​​the first faces on the surface of the sheet member is larger than a total area of ​​the second faces on the surface of the sheet member. [Supplementary Note 33] The sheet member according to any one of Supplements 29 to 32, wherein the total area of ​​the first faces on the surface of the sheet member and the total area of ​​the second faces on the surface of the sheet member are set based on a frequency at which the moving body moves in the first movement environment and a frequency at which the moving body moves in the second movement environment.[Supplementary Note 34] The sheet member according to any one of Supplements 29 to 33, wherein a ratio between a total area of ​​the first faces on the surface of the sheet member and a total area of ​​the second faces on the surface of the sheet member is set based on a ratio between a frequency at which the moving body moves in the first movement environment and a frequency at which the moving body moves in the second movement environment. [Supplementary Note 35] The first riblet structure includes a structure in which a plurality of first convex structures extending in a first direction along the first surface and protruding in a second direction intersecting with the first direction are formed so as to be aligned along the first surface and in a third direction intersecting with the first and second directions, and the second riblet structure includes a structure in which a plurality of second convex structures extending in a fourth direction along the second surface and protruding in a fifth direction intersecting with the fourth direction are formed so as to be aligned along the second surface and in a sixth direction intersecting with the fourth and fifth directions. [Appendix 36] The sheet member according to Appendix 35, wherein the characteristics of the first riblet structure include at least one of the pitch of the plurality of first convex structures, the height of each of the plurality of first convex structures, and the direction in which each of the plurality of first convex structures extends, and the characteristics of the second riblet structure include at least one of the pitch of the plurality of second convex structures, the height of each of the plurality of second convex structures, and the direction in which each of the plurality of second convex structures extends. [Appendix 37] The sheet member according to Appendix 35 or 36, wherein the pitch of the plurality of first convex structures is different from the pitch of the plurality of second convex structures. [Appendix 38] The sheet member according to any one of Appendices 35 to 37, wherein the height of each of the plurality of first convex structures is different from the height of each of the plurality of second convex structures. [Appendix 39] The sheet member according to any one of Appendices 35 to 38, wherein the direction in which each of the plurality of first convex structures extends is different from the direction in which each of the plurality of second convex structures extends. [Appendix 40] The sheet member according to any one of Appendices 21 to 39, wherein the shape of the first surface is different from the shape of the second surface.[Supplementary Note 41] The sheet member according to any one of Supplementary Notes 21 to 40, wherein the surface of the sheet member includes a plurality of the first surfaces and a plurality of the second surfaces, and the plurality of first surfaces and the plurality of second surfaces are arranged in a periodic or random arrangement pattern. [Supplementary Note 42] The sheet member according to Supplementary Note 41, wherein each of the plurality of first surfaces and the plurality of second surfaces has a shape whose longitudinal direction is a seventh direction along the surface of the sheet member, and the periodic arrangement pattern includes a stripe pattern in which the first surfaces and the second surfaces are alternately arranged along an eighth direction along the surface of the sheet member and intersecting the seventh direction. [Supplementary Note 43] The sheet member according to Supplementary Note 42, wherein the sheet member is attachable to at least a part of the surface of a movable body that can move through a fluid, and the seventh direction is along the direction in which the fluid flows on the surface of the movable body. [Appendix 44] The sheet member according to any one of Appendices 41 to 43, wherein the periodic arrangement pattern includes a grid pattern in which the first surfaces and the second surfaces are alternately arranged along a ninth direction along the surface of the sheet member and a tenth direction along the surface of the sheet member and intersecting the ninth direction. [Appendix 45] A movable body movable in a fluid, wherein the sheet member according to any one of Appendices 21 to 44 is attached to at least a portion of the surface of the movable body. [Appendix 46] A movable body movable in a fluid, wherein a plurality of the sheet members according to any one of Appendices 21 to 44 are attached to at least a portion of the surface of the movable body. [Appendix 47] A manufacturing apparatus for manufacturing the sheet member according to any one of Appendices 21 to 44. [Supplementary Note 48] A moving body capable of moving through a fluid, the surface of the moving body including a first surface to which a first sheet member having a first structure formed thereon is attached, and a second surface to which a second sheet member having a second structure formed thereon is attached, and the characteristics of the first structure are different from the characteristics of the second structure.[Supplementary Note 49] The moving body according to Supplementary Note 48, wherein the characteristic of the first structure is set to a first characteristic suitable for the purpose of reducing the resistance of the first surface against the fluid, and the characteristic of the second structure is set to a second characteristic suitable for the purpose of reducing the resistance of the second surface against the fluid. [Supplementary Note 50] The moving body according to Supplementary Note 48 or 49, wherein the moving body is movable in at least one of a first movement mode and a second movement mode, the characteristic of the first structure is set to a third characteristic suitable for the purpose of reducing the resistance of the moving body against the fluid when moving in the first movement mode, and the characteristic of the second structure is set to a fourth characteristic suitable for the purpose of reducing the resistance of the moving body against the fluid when moving in the second movement mode different from the first movement mode. [Supplementary Note 51] The moving body according to Supplementary Note 50, wherein each of the first and second movement modes includes a movement speed of the moving body. [Supplementary Note 52] The moving body according to Supplementary Note 50 or 51, wherein the moving body is capable of moving at a first moving speed and a second moving speed, the third characteristic is set to a characteristic suitable for the purpose of reducing resistance of the moving body moving at the first moving speed to the fluid, the fourth characteristic is set to a characteristic suitable for the purpose of reducing resistance of the moving body moving at the second moving speed to the fluid, and the frequency at which the moving body moves at the first moving speed in a first period is higher than the frequency at which the moving body moves at the second moving speed in the first period. [Supplementary Note 53] The moving body according to Supplementary Note 52, wherein at least one first sheet member is attached to the first surface, and at least one second sheet member is attached to the second surface, and a total area of ​​the first surfaces on the surface of the moving body is greater than a total area of ​​the second surfaces on the surface of the moving body.[Supplementary Note 54] The moving body according to any one of Supplementary Notes 50 to 53, wherein at least one first sheet member is attached to the first surface, and at least one second sheet member is attached to the second surface, and a total area of ​​the first surface on the surface of the moving body and a total area of ​​the second surface on the surface of the moving body are set based on a frequency at which the moving body moves in the first movement mode and a frequency at which the moving body moves in the second movement mode. [Supplementary Note 55] The moving body according to any one of Supplementary Notes 50 to 54, wherein at least one first sheet member is attached to the first surface, and at least one second sheet member is attached to the second surface, and a ratio of the total area of ​​the first surface on the surface of the moving body to the total area of ​​the second surface on the surface of the moving body is set based on a ratio of the frequency at which the moving body moves in the first movement mode and a frequency at which the moving body moves in the second movement mode. [Supplementary Note 56] The moving body according to any one of Supplementary Notes 48 to 55, wherein the characteristic of the first structure is set to a fifth characteristic suitable for the purpose of reducing resistance to the fluid of the moving body moving in a first moving environment, and the characteristic of the second structure is set to a sixth characteristic suitable for the purpose of reducing resistance to the fluid of the moving body moving in a second moving environment different from the first moving environment. [Supplementary Note 57] The moving body according to Supplementary Note 56, wherein each of the first and second moving environments includes a flow velocity of the fluid. [Appendix 58] The moving body described in Appendix 56 or 57, wherein the flow rate of the fluid includes a first flow rate and a second flow rate, the fifth characteristic is set to a characteristic suitable for the purpose of reducing the resistance of the moving body to the fluid at the first flow rate, the sixth characteristic is set to a characteristic suitable for the purpose of reducing the resistance of the moving body to the fluid at the second flow rate, and the frequency at which the fluid is at the first flow rate in a second period is higher than the frequency at which the fluid is at the second flow rate in the second period.[Supplementary Note 59] The moving body according to Supplementary Note 58, wherein at least one of the first sheet members is attached to the first surface, at least one of the second sheet members is attached to the second surface, and a total area of ​​the first surfaces on the surface of the moving body is larger than a total area of ​​the second surfaces on the surface of the moving body. [Supplementary Note 60] The moving body according to any one of Supplementary Notes 56 to 59, wherein at least one of the first sheet members is attached to the first surface, at least one of the second sheet members is attached to the second surface, and the total area of ​​the first surfaces on the surface of the moving body and the total area of ​​the second surfaces on the surface of the moving body are set based on a frequency at which the moving body moves in the first moving environment and a frequency at which the moving body moves in the second moving environment. [Appendix 61] A moving body described in any one of Appendices 56 to 60, wherein at least one of the first sheet members is attached to the first surface, and at least one of the second sheet members is attached to the second surface, and the ratio of the total area of ​​the first surfaces on the surface of the moving body to the total area of ​​the second surfaces on the surface of the moving body is set based on the ratio of the frequency at which the moving body moves in the first moving environment to the frequency at which the moving body moves in the second moving environment. [Appendix 62] The moving body described in any one of Appendices 48 to 61, wherein the first structure includes a structure in which a plurality of first convex structures extending along a first direction along the first surface and protruding along a second direction intersecting with the first direction are formed so as to be aligned along a third direction along the first surface and intersecting with the first and second directions, and the second structure includes a structure in which a plurality of second convex structures extending along a fourth direction along the second surface and protruding along a fifth direction intersecting with the fourth direction are formed so as to be aligned along the second surface and intersecting with the sixth direction.[Supplementary Note 63] The moving body according to Supplementary Note 62, wherein the characteristics of the first structure include at least one of the pitch of the plurality of first convex structures, the height of each of the plurality of first convex structures, and the direction in which each of the plurality of first convex structures extends, and the characteristics of the second structure include at least one of the pitch of the plurality of second convex structures, the height of each of the plurality of second convex structures, and the direction in which each of the plurality of second convex structures extends. [Supplementary Note 64] The moving body according to Supplementary Note 62 or 63, wherein the pitch of the plurality of first convex structures is different from the pitch of the plurality of second convex structures. [Supplementary Note 65] The moving body according to any one of Supplements 62 to 64, wherein the height of each of the plurality of first convex structures is different from the height of each of the plurality of second convex structures. [Appendix 66] The moving body according to any one of Appendices 62 to 65, wherein the direction in which each of the plurality of first convex structures extends is different from the direction in which each of the plurality of second convex structures extends. [Appendix 67] The moving body according to any one of Appendices 48 to 66, wherein the shape of the first sheet member is different from the shape of the second sheet member. [Appendix 68] A sheet member, wherein a surface of the sheet member includes a first surface on which a first structure is formed and a second surface on which a second structure is formed, and wherein a characteristic of the first structure is different from a characteristic of the second structure. [Appendix 69] The sheet member according to Appendices 68, wherein the sheet member is attachable to at least a portion of a surface of a moving body capable of moving through a fluid, and wherein a characteristic of the first structure is set to a first characteristic suitable for the purpose of reducing resistance of a first surface of the moving body to the fluid, and a characteristic of the second structure is set to a second characteristic suitable for the purpose of reducing resistance of a second surface of the moving body to the fluid.[Supplementary Note 70] The sheet member according to Supplementary Note 68 or 69, wherein the sheet member can be attached to at least a part of a surface of a moving body that can move through a fluid in at least one of a first movement mode and a second movement mode, and the characteristic of the first structure is set to a third characteristic suitable for the purpose of reducing resistance to the fluid of the moving body moving in the first movement mode, and the characteristic of the second structure is set to a fourth characteristic suitable for the purpose of reducing resistance to the fluid of the moving body moving in a second movement mode different from the first movement mode. [Supplementary Note 71] The sheet member according to Supplementary Note 70, wherein each of the first and second movement modes includes a movement speed of the moving body. [Appendix 72] The sheet member according to appendix 70 or 71, wherein the moving body is capable of moving at a first moving speed and a second moving speed, the third characteristic is set to a characteristic suitable for the purpose of reducing resistance of the moving body moving at the first moving speed to the fluid, the fourth characteristic is set to a characteristic suitable for the purpose of reducing resistance of the moving body moving at the second moving speed to the fluid, and the frequency at which the moving body moves at the first moving speed in a first period is higher than the frequency at which the moving body moves at the second moving speed in the first period. [Appendix 73] The sheet member according to appendix 72, wherein a total area of ​​the first faces on the surface of the sheet member is larger than a total area of ​​the second faces on the surface of the sheet member. [Appendix 74] The sheet member according to any one of appendices 70 to 73, wherein the total area of ​​the first faces on the surface of the sheet member and the total area of ​​the second faces on the surface of the sheet member are set based on a frequency at which the moving body moves in the first movement mode and a frequency at which the moving body moves in the second movement mode. [Appendix 75] The sheet member described in any one of Appendices 70 to 74, wherein the ratio of the total area of ​​the first surface on the surface of the sheet member to the total area of ​​the second surface on the surface of the sheet member is set based on the ratio of the frequency at which the moving body moves in the first movement mode to the frequency at which the moving body moves in the second movement mode.[Supplementary Note 76] The sheet member according to any one of Supplementary Notes 68 to 75, wherein the sheet member can be attached to at least a portion of a surface of a moving body that can move through a fluid, and the characteristic of the first structure is set to a fifth characteristic suitable for reducing resistance to the fluid of the moving body that moves in a first moving environment, and the characteristic of the second structure is set to a sixth characteristic suitable for reducing resistance to the fluid of the moving body that moves in a second moving environment different from the first moving environment. [Supplementary Note 77] The sheet member according to Supplementary Note 76, wherein each of the first and second moving environments includes a flow velocity of the fluid. [Appendix 78] The sheet member according to appendix 76 or 77, wherein the flow velocity of the fluid includes a first flow velocity and a second flow velocity, the fifth characteristic is set to a characteristic suitable for reducing resistance of the moving body to the fluid at the first flow velocity, the sixth characteristic is set to a characteristic suitable for reducing resistance of the moving body to the fluid at the second flow velocity, and a frequency at which the fluid has the first flow velocity in a second period is higher than a frequency at which the fluid has the second flow velocity in the second period. [Appendix 79] The sheet member according to appendix 78, wherein a total area of ​​the first faces on the surface of the sheet member is larger than a total area of ​​the second faces on the surface of the sheet member. [Appendix 80] The sheet member according to any one of appendices 76 to 79, wherein the total area of ​​the first faces on the surface of the sheet member and the total area of ​​the second faces on the surface of the sheet member are set based on a frequency at which the moving body moves in the first movement environment and a frequency at which the moving body moves in the second movement environment. [Appendix 81] The sheet member described in any one of Appendices 76 to 80, wherein the ratio of the total area of ​​the first surface on the surface of the sheet member to the total area of ​​the second surface on the surface of the sheet member is set based on the ratio of the frequency at which the moving body moves in the first moving environment to the frequency at which the moving body moves in the second moving environment.[Appendix 82] The sheet member described in any one of Appendices 68 to 81, wherein the first structure includes a structure in which a plurality of first convex structures extending along a first direction along the first surface and protruding along a second direction intersecting with the first direction are formed so as to be aligned along a third direction along the first surface and intersecting with the first and second directions, and the second structure includes a structure in which a plurality of second convex structures extending along a fourth direction along the second surface and protruding along a fifth direction intersecting with the fourth direction are formed so as to be aligned along the second surface and intersecting with the fourth and fifth directions. [Appendix 83] The sheet member according to Appendix 82, wherein the characteristics of the first structure include at least one of the pitch of the plurality of first convex structures, the height of each of the plurality of first convex structures, and the direction in which each of the plurality of first convex structures extends, and the characteristics of the second structure include at least one of the pitch of the plurality of second convex structures, the height of each of the plurality of second convex structures, and the direction in which each of the plurality of second convex structures extends. [Appendix 84] The sheet member according to Appendix 82 or 83, wherein the pitch of the plurality of first convex structures is different from the pitch of the plurality of second convex structures. [Appendix 85] The sheet member according to any one of Appendices 82 to 84, wherein the height of each of the plurality of first convex structures is different from the height of each of the plurality of second convex structures. [Appendix 86] The sheet member according to any one of Appendices 82 to 85, wherein the direction in which each of the plurality of first convex structures extends is different from the direction in which each of the plurality of second convex structures extends. [Appendix 87] The sheet member according to any one of Appendices 68 to 86, wherein the shape of the first surface is different from the shape of the second surface. [Appendix 88] The sheet member according to any one of Appendices 68 to 87, wherein the surface of the sheet member includes a plurality of the first surfaces and a plurality of the second surfaces, and the plurality of first surfaces and the plurality of second surfaces are arranged in a periodic or random arrangement pattern.[Appendix 89] The sheet member according to Appendix 88, wherein each of the plurality of first surfaces and the plurality of second surfaces has a shape whose longitudinal direction is a seventh direction along the surface of the sheet member, and the periodic arrangement pattern includes a stripe pattern in which the first surfaces and the second surfaces are alternately arranged along an eighth direction that is along the surface of the sheet member and intersects with the seventh direction. [Appendix 90] The sheet member according to Appendix 89, wherein the sheet member is attachable to at least a part of a surface of a movable body that can move through a fluid, and the seventh direction is along a direction in which the fluid flows on the surface of the movable body. [Appendix 91] The sheet member according to any one of Appendices 88 to 90, wherein the periodic arrangement pattern includes a grid pattern in which the first surfaces and the second surfaces are alternately arranged along a ninth direction along the surface of the sheet member and a tenth direction that is along the surface of the sheet member and intersects with the ninth direction. [Appendix 92] A moving body that can move through a fluid, wherein the sheet member described in any one of Appendices 68 to 91 is attached to at least a portion of the surface of the moving body. [Appendix 93] A moving body that can move through a fluid, wherein a plurality of sheet members described in any one of Appendices 68 to 91 are attached to at least a portion of the surface of the moving body. [Appendix 94] A manufacturing device for manufacturing the sheet member described in any one of Appendices 68 to 91. [Appendix 95] A modification method for a moving body that can move through a fluid, comprising: attaching a first sheet member having a first riblet structure formed on a first surface of the surface of the moving body; and attaching a second sheet member having a second riblet structure formed on a second surface of the surface of the moving body that is different from the first surface, wherein characteristics of the first riblet structure are different from characteristics of the second riblet structure.[Appendix 96] A method for modifying a moving body described in Appendix 95, further comprising: determining the characteristics of the first riblet structure of the first sheet member attached to the first surface based on the movement mode of the moving body; and determining the characteristics of the second riblet structure of the second sheet member attached to the second surface based on the movement mode of the moving body.

[0153] The requirements of the above-described embodiments may be combined as appropriate. Some of the requirements of the above-described embodiments may not be used. The requirements of the above-described embodiments may be replaced with requirements of other embodiments as appropriate. Furthermore, to the extent permitted by law, the disclosures of all publications and U.S. patents relating to the devices, etc. cited in the above-described embodiments are incorporated herein by reference.

[0154] Furthermore, the present invention can be modified as appropriate within the scope that does not contradict the gist or idea of ​​the invention that can be read from the claims and the entire specification, and the moving body, sheet member, and manufacturing device that involve such modifications are also included in the technical idea of ​​the present invention.

[0155] 1, 1a, 1b riblet sheet 11 adhesive layer 12 coating layer 121 paint layer 122 coating layer 130 riblet structure surface 191 convex structure 192 groove structure RB riblet structure OBJ object

Claims

1. A moving body capable of moving through a fluid, the surface of the moving body including a first surface to which a first sheet member having a first riblet structure formed thereon is attached, and a second surface to which a second sheet member having a second riblet structure formed thereon is attached, the characteristics of the first riblet structure being different from the characteristics of the second riblet structure.

2. A moving body as described in claim 1, wherein the characteristics of the first riblet structure are set to first characteristics suitable for the purpose of reducing the resistance of the first surface to the fluid, and the characteristics of the second riblet structure are set to second characteristics suitable for the purpose of reducing the resistance of the second surface to the fluid.

3. A moving body as described in claim 1 or 2, wherein the moving body is capable of moving in at least one of a first movement mode and a second movement mode, the characteristics of the first riblet structure are set to a third characteristic suitable for the purpose of reducing the resistance of the moving body moving in the first movement mode to the fluid, and the characteristics of the second riblet structure are set to a fourth characteristic suitable for the purpose of reducing the resistance of the moving body moving in the second movement mode different from the first movement mode to the fluid.

4. The moving body according to claim 3, wherein each of the first and second movement modes includes a moving speed of the moving body.

5. A moving body as described in claim 3 or 4, wherein the moving body is capable of moving at a first moving speed and a second moving speed, the third characteristic is set to a characteristic suitable for the purpose of reducing the resistance of the moving body moving at the first moving speed to the fluid, the fourth characteristic is set to a characteristic suitable for the purpose of reducing the resistance of the moving body moving at the second moving speed to the fluid, and the frequency at which the moving body moves at the first moving speed in a first period is higher than the frequency at which the moving body moves at the second moving speed in the first period.

6. A moving body as described in claim 5, wherein at least one of the first sheet members is attached to the first surface, and at least one of the second sheet members is attached to the second surface, and the total area of ​​the first surfaces on the surface of the moving body is greater than the total area of ​​the second surfaces on the surface of the moving body.

7. A moving body as described in any one of claims 3 to 6, wherein at least one of the first sheet members is attached to the first surface, and at least one of the second sheet members is attached to the second surface, and the total area of ​​the first surfaces on the surface of the moving body and the total area of ​​the second surfaces on the surface of the moving body are set based on the frequency at which the moving body moves in the first movement mode and the frequency at which the moving body moves in the second movement mode.

8. A moving body as described in any one of claims 3 to 7, wherein at least one of the first sheet members is attached to the first surface, and at least one of the second sheet members is attached to the second surface, and a ratio between a total area of ​​the first surface on the surface of the moving body and a total area of ​​the second surface on the surface of the moving body is set based on a ratio between a frequency at which the moving body moves in the first movement mode and a frequency at which the moving body moves in the second movement mode.

9. A moving body as described in any one of claims 1 to 8, wherein the characteristics of the first riblet structure are set to a fifth characteristic suitable for the purpose of reducing the resistance of the moving body moving in a first moving environment to the fluid, and the characteristics of the second riblet structure are set to a sixth characteristic suitable for the purpose of reducing the resistance of the moving body moving in a second moving environment different from the first moving environment to the fluid.

10. The moving body according to claim 9, wherein each of the first and second moving environments includes a flow velocity of the fluid.

11. A moving body as described in claim 9 or 10, wherein the flow rate of the fluid includes a first flow rate and a second flow rate, the fifth characteristic is set to a characteristic suitable for the purpose of reducing the resistance of the moving body to the fluid at the first flow rate, the sixth characteristic is set to a characteristic suitable for the purpose of reducing the resistance of the moving body to the fluid at the second flow rate, and the frequency with which the fluid is at the first flow rate in a second period is higher than the frequency with which the fluid is at the second flow rate in the second period.

12. A moving body as described in claim 11, wherein at least one of the first sheet members is attached to the first surface, and at least one of the second sheet members is attached to the second surface, and the total area of ​​the first surfaces on the surface of the moving body is greater than the total area of ​​the second surfaces on the surface of the moving body.

13. A moving body as described in any one of claims 9 to 12, wherein at least one of the first sheet members is attached to the first surface, and at least one of the second sheet members is attached to the second surface, and the total area of ​​the first surfaces on the surface of the moving body and the total area of ​​the second surfaces on the surface of the moving body are set based on the frequency with which the moving body moves in the first moving environment and the frequency with which the moving body moves in the second moving environment.

14. A moving body as described in any one of claims 9 to 13, wherein at least one of the first sheet members is attached to the first surface, and at least one of the second sheet members is attached to the second surface, and a ratio between a total area of ​​the first surfaces on the surface of the moving body and a total area of ​​the second surfaces on the surface of the moving body is set based on a ratio between a frequency at which the moving body moves in the first moving environment and a frequency at which the moving body moves in the second moving environment.

15. A moving body as described in any one of claims 1 to 14, wherein the first riblet structure includes a structure in which a plurality of first convex structures extending along a first direction along the first surface and protruding along a second direction intersecting the first direction are formed so as to be aligned along the first surface and along a third direction intersecting the first and second directions, and the second riblet structure includes a structure in which a plurality of second convex structures extending along a fourth direction along the second surface and protruding along a fifth direction intersecting the fourth direction are formed so as to be aligned along the second surface and along a sixth direction intersecting the fourth and fifth directions.

16. A moving body as described in claim 15, wherein the characteristics of the first riblet structure include at least one of the pitch of the multiple first convex structures, the height of each of the multiple first convex structures, and the direction in which each of the multiple first convex structures extends, and the characteristics of the second riblet structure include at least one of the pitch of the multiple second convex structures, the height of each of the multiple second convex structures, and the direction in which each of the multiple second convex structures extends.

17. A moving body according to claim 15 or 16, wherein the pitch of the plurality of first convex structures is different from the pitch of the plurality of second convex structures.

18. A moving body according to any one of claims 15 to 17, wherein the height of each of the plurality of first convex structures is different from the height of each of the plurality of second convex structures.

19. A moving body according to any one of claims 15 to 18, wherein the direction in which each of the plurality of first convex structures extends is different from the direction in which each of the plurality of second convex structures extends.

20. A moving body as claimed in any one of claims 1 to 19, wherein the shape of the first sheet member is different from the shape of the second sheet member.

21. A sheet member, wherein a surface of the sheet member includes a first surface on which a first riblet structure is formed and a second surface on which a second riblet structure is formed, and the characteristics of the first riblet structure are different from the characteristics of the second riblet structure.

22. The sheet member described in claim 21, wherein the sheet member is attachable to at least a portion of the surface of a moving body capable of moving through a fluid, the characteristics of the first riblet structure are set to first characteristics suitable for the purpose of reducing the resistance of a first side of the surface of the moving body to the fluid, and the characteristics of the second riblet structure are set to second characteristics suitable for the purpose of reducing the resistance of a second side of the surface of the moving body to the fluid.

23. The sheet member described in claim 21 or 22, wherein the sheet member is attachable to at least a portion of the surface of a moving body capable of moving through a fluid in at least either a first movement mode or a second movement mode, the characteristics of the first riblet structure are set to a third characteristic suitable for the purpose of reducing the resistance of the moving body moving in the first movement mode to the fluid, and the characteristics of the second riblet structure are set to a fourth characteristic suitable for the purpose of reducing the resistance of the moving body moving in a second movement mode different from the first movement mode to the fluid.

24. The sheet member according to claim 23, wherein each of the first and second movement modes includes a movement speed of the moving body.

25. A sheet member as described in claim 23 or 24, wherein the moving body is capable of moving at a first moving speed and a second moving speed, the third characteristic is set to a characteristic suitable for the purpose of reducing the resistance of the moving body moving at the first moving speed to the fluid, the fourth characteristic is set to a characteristic suitable for the purpose of reducing the resistance of the moving body moving at the second moving speed to the fluid, and the frequency at which the moving body moves at the first moving speed in a first period is higher than the frequency at which the moving body moves at the second moving speed in the first period.

26. The sheet member according to claim 25, wherein the total area of ​​the first faces on the surface of the sheet member is greater than the total area of ​​the second faces on the surface of the sheet member.

27. A sheet member as described in any one of claims 23 to 26, wherein the total area of ​​the first surfaces on the surface of the sheet member and the total area of ​​the second surfaces on the surface of the sheet member are set based on the frequency with which the moving body moves in the first movement mode and the frequency with which the moving body moves in the second movement mode.

28. A sheet member as described in any one of claims 23 to 27, wherein the ratio of the total area of ​​the first side on the surface of the sheet member to the total area of ​​the second side on the surface of the sheet member is set based on the ratio of the frequency at which the moving body moves in the first movement mode to the frequency at which the moving body moves in the second movement mode.

29. A sheet member as described in any one of claims 21 to 28, wherein the sheet member is attachable to at least a portion of a surface of a moving body capable of moving through a fluid, the characteristics of the first riblet structure are set to a fifth characteristic suitable for the purpose of reducing the resistance of the moving body moving in a first moving environment to the fluid, and the characteristics of the second riblet structure are set to a sixth characteristic suitable for the purpose of reducing the resistance of the moving body moving in a second moving environment different from the first moving environment to the fluid.

30. The sheet member according to claim 29, wherein each of the first and second moving environments includes a flow rate of the fluid.

31. A sheet member as described in claim 29 or 30, wherein the flow rate of the fluid includes a first flow rate and a second flow rate, the fifth characteristic is set to a characteristic suitable for the purpose of reducing the resistance of the moving body to the fluid at the first flow rate, the sixth characteristic is set to a characteristic suitable for the purpose of reducing the resistance of the moving body to the fluid at the second flow rate, and the frequency with which the fluid is at the first flow rate in a second period is higher than the frequency with which the fluid is at the second flow rate in the second period.

32. A sheet member according to claim 31, wherein the total area of ​​the first faces on the surface of the sheet member is greater than the total area of ​​the second faces on the surface of the sheet member.

33. A sheet member as described in any one of claims 29 to 32, wherein the total area of ​​the first surfaces on the surface of the sheet member and the total area of ​​the second surfaces on the surface of the sheet member are set based on the frequency with which the moving body moves in the first moving environment and the frequency with which the moving body moves in the second moving environment.

34. A sheet member as described in any one of claims 29 to 33, wherein the ratio of the total area of ​​the first surfaces on the surface of the sheet member to the total area of ​​the second surfaces on the surface of the sheet member is set based on the ratio of the frequency at which the moving body moves in the first moving environment to the frequency at which the moving body moves in the second moving environment.

35. A sheet member described in any one of claims 21 to 34, wherein the first riblet structure includes a structure in which a plurality of first convex structures extending along a first direction along the first surface and protruding along a second direction intersecting the first direction are formed so as to be aligned along the first surface and along a third direction intersecting the first and second directions, and the second riblet structure includes a structure in which a plurality of second convex structures extending along a fourth direction along the second surface and protruding along a fifth direction intersecting the fourth direction are formed so as to be aligned along the second surface and along a sixth direction intersecting the fourth and fifth directions.

36. A sheet member as described in claim 35, wherein characteristics of the first riblet structure include at least one of the pitch of the plurality of first convex structures, the height of each of the plurality of first convex structures, and the direction in which each of the plurality of first convex structures extends, and characteristics of the second riblet structure include at least one of the pitch of the plurality of second convex structures, the height of each of the plurality of second convex structures, and the direction in which each of the plurality of second convex structures extends.

37. A sheet member according to claim 35 or 36, wherein the pitch of the plurality of first convex structures is different from the pitch of the plurality of second convex structures.

38. A sheet member according to any one of claims 35 to 37, wherein the height of each of the plurality of first convex structures is different from the height of each of the plurality of second convex structures.

39. A sheet member according to any one of claims 35 to 38, wherein the direction in which each of the plurality of first convex structures extends is different from the direction in which each of the plurality of second convex structures extends.

40. A sheet member according to any one of claims 21 to 39, wherein the shape of the first surface is different from the shape of the second surface.

41. A sheet member according to any one of claims 21 to 40, wherein the surface of the sheet member includes a plurality of the first surfaces and a plurality of the second surfaces, and the plurality of first surfaces and the plurality of second surfaces are arranged in a periodic or random arrangement pattern.

42. The sheet member described in claim 41, wherein each of the plurality of first surfaces and the plurality of second surfaces has a shape whose longitudinal direction is a seventh direction along the surface of the sheet member, and the periodic arrangement pattern includes a stripe pattern in which the first surfaces and the second surfaces are alternately arranged along an eighth direction that runs along the surface of the sheet member and intersects with the seventh direction.

43. The sheet member according to claim 42, wherein the sheet member is attachable to at least a portion of a surface of a movable body capable of moving through a fluid, and the seventh direction is aligned with a direction in which the fluid flows on the surface of the movable body.

44. A sheet member as described in any one of claims 41 to 43, wherein the periodic arrangement pattern includes a grid pattern in which the first surfaces and the second surfaces are alternately arranged along a ninth direction along the surface of the sheet member and a tenth direction along the surface of the sheet member and intersecting the ninth direction.

45. A moving body capable of moving through a fluid, the moving body having a sheet member according to any one of claims 21 to 44 attached to at least a portion of a surface of the moving body.

46. ​​A moving body capable of moving through a fluid, comprising a plurality of sheet members according to any one of claims 21 to 44 attached to at least a portion of a surface of the moving body.

47. A manufacturing apparatus for manufacturing a sheet member according to any one of claims 21 to 44.

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