Sheet member and moving body

Abstract

A film-like sheet member 1 having a riblet structure RB formed on a surface 130 thereof, said sheet member being provided with a first surface 131, a second surface 132, and a third surface 133 positioned between the first surface and the second surface, and being configured in a manner such that: a plurality of first convex structures 191 which extend in a first direction in which the first to third surfaces are arranged and protrude in a second direction which intersects the first direction are formed on the first and second surfaces as a part of the riblet structure so as to be aligned in a third direction, which intersects the first and second directions; and the third surface is concave with respect to the first and second surfaces.

Description

Sheet members, moving bodies

[0001] The present invention relates to the technical field of, for example, a sheet member having a riblet structure formed on its surface, and a mobile body to which the sheet member is attached.

[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. 2011 / 0186685

[0004] According to a first aspect, a film-like sheet member having a riblet structure formed on its surface is provided, the sheet member having a first surface, a second surface, and a third surface located between the first surface and the second surface, and on the first surface, as part of the riblet structure, a plurality of first convex structures are formed, the first convex structures extending in a first direction in which the first to third surfaces are aligned and protruding from the first surface in a second direction intersecting the first direction, and aligned along the first to third surfaces and in a third direction intersecting the first and second directions, and on the second surface, as part of the riblet structure, a plurality of second convex structures extending in the first direction and protruding from the second surface in the second direction, and aligned in the third direction, and the third surface is concave with respect to the first and second surfaces.

[0005] According to a second aspect, there is provided a moving body having the sheet member provided by the first aspect attached to at least a part of its surface.

[0006] According to a third aspect, a film-like sheet member having a riblet structure formed on its surface is provided, the sheet member having a first surface, a second surface, and a third surface located between the first surface and the second surface, and on the first surface, as part of the riblet structure, a plurality of first convex structures are formed that protrude relative to the first surface in a second direction that intersects the first direction in which the first to third surfaces are aligned, and are aligned in a third direction that intersects the first and second directions, and on the second surface, as part of the riblet structure, a plurality of second convex structures are formed that protrude relative to the second surface in the second direction, and are aligned in the third direction, and the third surface is concave with respect to the first and second surfaces.

[0007] According to a fourth aspect, there is provided a moving body having the sheet member provided by the third aspect attached to at least a part of its surface.

[0008] According to a fifth aspect, there is provided a film-like sheet member having a first direction as its longitudinal direction, the sheet member having a surface on which a riblet structure is formed and a plurality of recesses formed within the surface and extending in a direction intersecting the first direction, the plurality of recesses including a first recess and a second recess, and the surface between the first recess and the second recess has a plurality of convex structures formed in a direction intersecting the first direction as at least part of the riblet structure, the convex structures extending in the first direction and protruding relative to the surface.

[0009] 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(a) is a perspective view showing a libretto structure of a comparative example, and FIG. 4(b) is a cross-sectional view showing the libretto structure of the comparative example. FIG. 5(a) is a perspective view showing the libretto structure formed in the libretto sheet of this embodiment, and FIG. 5(b) is a cross-sectional view showing the libretto structure formed in the libretto sheet of this embodiment. Fig. 6(a) is a perspective view showing the riblet structure formed on the riblet sheet of a first modified example, Fig. 6(b) is a cross-sectional view showing the riblet structure formed on the riblet sheet of the first modified example, Fig. 7 is a perspective view showing the riblet structure formed on the riblet sheet of a second modified example, and Fig. 8 is a top view schematically showing the riblet structure formed on the riblet sheet of a third modified example.

[0010] Next, embodiments of the sheet member and the moving body will be described with reference to the drawings.

[0011] (1) Structure of Libretto Sheet 1 First, the structure of the libretto sheet 1, which is an example of an embodiment of a seat member, 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 1 of this 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 1 of this embodiment.

[0012] As shown in FIGS. 1( a) and 1(b), the libretto sheet 1 is a film-like (in other words, sheet-like, layer-like, foil-like, tape-like, or band-like) sheet member. In the example shown in FIGS. 1(a) and 1(b), the Y-axis direction is the width direction of the libretto sheet 1, and the Z-axis direction is the thickness direction of the libretto sheet 1. The libretto sheet 1 is a film-like sheet member whose thickness is much smaller than its width. As an example, the width of the libretto sheet 1 may be several centimeters or more, a dozen centimeters or more, several tens of centimeters or more, or one meter or more. On the other hand, the thickness of the libretto sheet 1 may be one millimeter or less, one centimeter or less, or a few centimeters or less.

[0013] The libretto sheet 1 has a longitudinal shape extending along a length direction intersecting the width direction and the thickness direction. In other words, the libretto sheet 1 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 1. As an example, the length of the libretto sheet 1 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.

[0014] However, the riblet sheet 1 does not have to have a longitudinal shape extending along a length direction intersecting the width direction and thickness direction. For example, the riblet sheet 1 may have a rectangular shape in a plan view. As an example, the riblet sheet 1 extending along the length direction may be divided along the length direction into multiple sheet members, each having a rectangular shape.

[0015] As shown in FIG. 1( b), the libretto sheet 1 may include an adhesive layer 11 and a coating layer 12. The adhesive layer 11 is a layer containing an adhesive for attaching the coating layer 12 to an object (e.g., a moving object, as described below). Therefore, the libretto sheet 1 may be attached to the object via the adhesive layer 11. The libretto sheet 1 may not include the adhesive layer 11. In this case, when attaching the libretto sheet 1 to the object, an operator may apply adhesive between the object and the libretto sheet 1. 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 may not include at least one of the paint layer 121 and the coating layer 122. The coating layer 12 may include a layer different from 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 being reflected on the surface of the coating layer 12. The coating layer 12 may 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.

[0016] A riblet structure RB is formed on the surface of the libretto sheet 1. However, in Figures 1(a) and 1(b), the riblet structure RB formed on the surface of the libretto sheet 1 is omitted for simplicity of the drawings. The riblet structure RB formed on the surface of the libretto sheet 1 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 1 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.

[0017] 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.

[0018] 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.

[0019] 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 below) 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 1, and the other of the stretching direction and the arrangement direction may be the lateral direction of the liblet sheet 1. 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 1, are arranged along the Y-axis direction, which is the width direction of the liblet sheet 1. 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.

[0020] 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 1. 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 1. 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.

[0021] The convex structure 191 has, for example, a pair of side surfaces 1911 and 1912 facing opposite to each other. Note that in this 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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 first 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.

[0027] 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 a groove facing boundary portion 1914 and side surfaces 1911 and 1912 connected by boundary portion 1914.

[0028] It should be noted that the riblet structure surface 130 may be considered to include a boundary portion 1914 (e.g., the bottom surface of the groove structure 192) in addition to or instead of the side surfaces 1911 and 1912.

[0029] 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 equal pitches 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 equal pitches along a predetermined arrangement direction. 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 1, and at least two convex structures 191 are arranged regularly according to the same first rule in a second portion of the surface of the libretto sheet 1. 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 the first portion of the surface of the libretto sheet 1, while at least two convex structures 191 are arranged regularly according to a second rule that is different from the first rule in the second portion of the surface of the libretto sheet 1. Furthermore, since the convex structures 191 and the groove structures 192 are formed alternately, a state in which multiple convex structures 191 are arranged regularly may be considered equivalent to a state in which multiple groove structures 192 are arranged regularly.

[0030] 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 also be referred to as the depth from the vertex or ridge line (i.e., the corner portion 1913) of the convex structure 191.

[0031] 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 (typically, the riblet structure surface 130) of the riblet sheet 1. 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 (typically, the riblet structure surface 130) of the riblet sheet 1.

[0032] The riblet sheet 1 on which the riblet structure RB is formed may be attached to an object via the adhesive layer 11. In this case, the riblet structure RB may be used as a structure that can reduce the resistance of the surface of the object to which the riblet sheet 1 is attached to a fluid (particularly, at least one of frictional resistance and turbulent frictional resistance). For this reason, the riblet sheet 1 may be attached to an object having a component that is 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) that flows relative to the surface of the object. For example, if the surface of an object 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).

[0033] An example of an object to which the riblet sheet 1 can be attached is a moving body. In particular, an example of an object to which the riblet sheet 1 can be 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.

[0034] For example, Figures 3(a) and 3(b) show an aircraft PL having a riblet sheet 1 attached to at least a portion of its surface. As shown in Figures 3(a) and 3(b), the riblet sheet 1 may be attached to at least a portion of the fuselage PL1 of the aircraft PL. The riblet sheet 1 may be attached to at least a portion of the main wing PL2 of the aircraft PL. The riblet sheet 1 may be attached to at least a portion of the vertical tail PL3 of the aircraft PL. The riblet sheet 1 may be attached to at least a portion of the horizontal tail PL4 of the aircraft PL.

[0035] When such a riblet sheet 1 is attached to at least a portion of the surface of a moving body (or any object, 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 1 is attached to at least a portion of the surface of an aircraft, the resistance that hinders the movement of the aircraft is reduced, leading to fuel savings for the aircraft. For example, when the riblet sheet 1 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 1 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 1 is attached to at least a portion of the surface of a power-generating turbine (particularly, a turbine blade), resistance that impedes the movement (typically, rotation) of the power-generating turbine is reduced, leading to higher efficiency of the power-generating turbine (i.e., improved power generation efficiency). As a result, the riblet sheet 1 has the potential to contribute to "13.2.2 Reduce 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."

[0036] (2) Riblet structure RB that prevents deterioration of the drag reduction effect Examples of a method for manufacturing a riblet sheet 1 having the above-mentioned riblet structure RB formed therein include the methods disclosed in, for example, U.S. Patent No. 8,147,234 and U.S. Patent No. 8,485,811.

[0037] An example of a libretto sheet 1 manufactured by the above-described method is shown in Figures 4(a) and 4(b). As shown in Figures 4(a) and 4(b), in some cases, a riblet structure RB may be formed on the riblet structure surface 130 of the riblet sheet 1, in which each convex structure 191 extending along a predetermined extension direction (X-axis direction) is separated along the predetermined extension direction (X-axis direction) by a barrier portion 199 that protrudes from the surrounding area and extends along the width direction of the riblet sheet 1. In other words, as shown in Figures 4(a) and 4(b), a riblet structure RB may be formed on the riblet structure surface 130 of the riblet sheet 1, in which each convex structure 191 extending along the predetermined extension direction (X-axis direction) is separated along the predetermined extension direction (X-axis direction) by a barrier portion 199 that is higher than the surrounding area. In other words, as shown in Figures 4(a) and 4(b), a riblet structure RB may be formed on the riblet structure surface 130 of the riblet sheet 1, in which each groove structure 192 extending along a predetermined extension direction (X-axis direction) is separated in the predetermined extension direction (X-axis direction) by a barrier portion 199 that protrudes from the surrounding area (i.e., is higher than the surrounding area).

[0038] In this case, as shown in Figures 4(a) and 4(b), the barrier portion 199 may act on the fluid as an obstacle that blocks the flow of the fluid that flows between two adjacent convex structures 191 and along the convex structures 191. In other words, the barrier portion 199 may act on the fluid as an obstacle that blocks the flow of the fluid that flows within the groove structure 192 and along the groove structure 192. As a result, when the barrier portion 199 is present, the resistance to the fluid of the surface of the moving body to which the riblet sheet 1 is attached may be higher than when the barrier portion 199 is not present. In other words, the resistance reduction effect of the riblet structure RB may be reduced. As a result, the moving body to which the riblet sheet 1 is attached may not be able to fully enjoy the resistance reduction effect of the riblet structure RB (i.e., the effect of reducing the resistance to the fluid of the surface of the moving body to which the riblet sheet 1 is attached). In particular, the higher the barrier portion 199 that separates the convex structure 191 and the groove structure 192, the more likely it is that a moving body to which the riblet sheet 1 is attached will not be able to fully enjoy the resistance reduction effect. Furthermore, if the height of the barrier portion 199 is higher than the height of the apex or ridge of the convex structure 191, the more likely it is that a moving body to which the riblet sheet 1 is attached will not be able to fully enjoy the resistance reduction effect.

[0039] Therefore, in this embodiment, as shown in Figures 5(a) and 5(b), a riblet structure RB is formed on the riblet structure surface 130 of the riblet sheet 1 so that barrier portions 199 that separate the convex structures 191 and the groove structures 192 are not formed. That is, a riblet structure RB in which the convex structures 191 and the groove structures 192 are not separated by barrier portions 199 is formed on the riblet structure surface 130 of the riblet sheet 1. In other words, a riblet structure RB that does not include barrier portions 199 that separate the convex structures 191 and the groove structures 192 is formed on the riblet structure surface 130 of the riblet sheet 1. As a result, as shown in Figures 5(a) and 5(b), the flow of fluid flowing along the convex structures 191 between two adjacent convex structures 191 is unlikely to be blocked by the barrier portions 199 that are obstacles. That is, the flow of fluid flowing within the groove structures 192 along the groove structures 192 is unlikely to be blocked by the barrier portions 199 that are obstacles. As a result, in this embodiment, the resistance to the fluid of the surface of the moving body to which the riblet sheet 1 is attached is lower than when the barrier portion 199 is present. In other words, there is little possibility that the resistance reduction effect of the riblet structure RB will deteriorate. As a result, a moving body to which the riblet sheet 1 is attached can fully enjoy the resistance reduction effect of the riblet structure RB. Furthermore, in this embodiment, because there is less possibility that turbulence will occur due to the barrier portion 199, there is also less possibility that the resistance reduction effect of the riblet structure RB will deteriorate due to that turbulence.

[0040] The riblet structure surface 130 on which a riblet structure RB that prevents a deterioration in the drag reduction effect is formed may include a first surface 131, a second surface 132, and a third surface 133 that are aligned along the extension direction (X-axis direction) of the riblet structure RB, as shown in Figures 5(a) and 5(b). In the following description, as shown in Figures 5(a) and 5(b), a portion of the riblet sheet 1 including the first surface 131 will be referred to as a first sheet portion (in other words, a first portion or a first region) 141, a portion of the riblet sheet 1 including the second surface 132 will be referred to as a second sheet portion (in other words, a second portion or a second region) 142, and a portion of the riblet sheet 1 including the third surface 133 will be referred to as a third sheet portion (in other words, a third portion or a third region) 143. Alternatively, the first surface 131, the second surface 132, and the third surface 133 themselves may be referred to as the first portion (first region), the second portion (second region), and the third portion (third region), respectively.

[0041] A part of the riblet structure RB may be formed on the first surface 131. In other words, a part of the riblet structure RB may be formed on the first sheet portion 141. Specifically, the first surface 131 may have convex structures 191 formed thereon that protrude from the first surface 131 along a predetermined height direction (Z-axis direction). The first surface 131 may have a first group of convex structures 191 formed thereon, the first group including a plurality of convex structures 191 extending continuously or intermittently along a predetermined extension direction and arranged along a predetermined arrangement direction. The first surface 131 may have a first group of groove structures 192 formed thereon, the first group including a plurality of groove structures 192 extending continuously or intermittently along the predetermined extension direction and arranged along the predetermined arrangement direction.

[0042] Another part of the riblet structure RB may be formed on the second surface 132. In other words, another part of the riblet structure RB may be formed on the second sheet portion 142. Specifically, the second surface 132 may have convex structures 191 formed thereon that protrude from the second surface 132 along a predetermined height direction (Z-axis direction). The second surface 132 may have a second group of convex structures 191 formed thereon, the second group including a plurality of convex structures 191 extending continuously or intermittently along the predetermined extension direction and arranged along a predetermined arrangement direction. The second surface 132 may have a second group of groove structures 192 formed thereon, the second group including a plurality of groove structures 192 extending continuously or intermittently along the predetermined extension direction and arranged along the predetermined arrangement direction.

[0043] The same riblet structure RB may be formed on the first surface 131 and the second surface 132. In other words, the first surface 131 and the second surface 132 may have the same riblet structure RB. Note that the state in which "the same riblet structure RB is formed on the first surface 131 and the second surface 132" may include a state in which "the characteristics of the riblet structure RB formed on the first surface 131 and the characteristics of the riblet structure RB formed on the second surface 132 are the same." The characteristics of the riblet structure RB may include at least one of the pitch P_rb of the convex structures 191 that make up the riblet structure RB, the height H_rb of the convex structures 191 that make up the riblet structure RB, the extension direction of the convex structures 191 that make up the riblet structure RB, and the arrangement direction of the convex structures 191 that make up the riblet structure RB.

[0044] However, different riblet structures RB may be formed on the first surface 131 and the second surface 132. In other words, the first surface 131 and the second surface 132 may have different riblet structures RB. Note that the state in which "different riblet structures RB are formed on the first surface 131 and the second surface 132" may also include a state in which "the characteristics of the riblet structure RB formed on the first surface 131 and the characteristics of the riblet structure RB formed on the second surface 132 are different."

[0045] The third surface 133 is located between the first surface 131 and the second surface 132 along the extension direction of the riblet structure RB (i.e., the length direction of the riblet sheet 1). In other words, the third sheet portion 143 is located between the first sheet portion 141 and the second sheet portion 142 along the extension direction of the riblet structure RB.

[0046] The third surface 133 may not have a riblet structure RB formed thereon. In other words, the third sheet portion 143 may not have a riblet structure RB formed thereon. Specifically, the third surface 133 (third sheet portion 143) may not have the convex structures 191 and groove structures 192 that constitute the riblet structure RB formed thereon. The third surface 133 (third sheet portion 143) may not have the convex structures 191 and groove structures 192 that constitute the riblet structure RB. In this case, the third surface 133 on which the riblet structure RB is not formed may be considered to be concave with respect to the first surface 131 and the second surface 132 on which the riblet structure RB is formed. The third sheet portion 143 on which the riblet structure RB is not formed may be considered to be concave with respect to the first sheet portion 141 and the second sheet portion 142 on which the riblet structure RB is formed. Specifically, the third surface 133 on which the riblet structure RB is not formed may be considered to be concave with respect to the riblet structure RB (particularly, the convex structure 191) formed on the first surface 131 and the second surface 132. The third sheet portion 143 on which the riblet structure RB is not formed may be considered to be concave with respect to the riblet structure RB (particularly, the convex structure 191) formed on the first sheet portion 141 and the second sheet portion 142. Therefore, each of the third surface 133 and the third sheet portion 143 may be referred to as a recessed portion because it is concave with respect to the riblet structure RB (particularly, the convex structure 191). Note that the first surface 131 and the second surface 132 on which the riblet structure RB is formed may be considered to be convex with respect to the third surface 133 on which the riblet structure RB is not formed. The first sheet portion 141 and the second sheet portion 142 on which the riblet structure RB is formed may be considered to be convex relative to the third sheet portion 143 on which the riblet structure RB is not formed. Specifically, the riblet structure RB (particularly the convex structure 191) formed on the first surface 131 and the second surface 132 may be considered to be convex relative to the third surface 133 on which the riblet structure RB is not formed.The riblet structure RB (particularly, the convex structure 191) formed in the first sheet portion 141 and the second sheet portion 142 may be considered to be convex relative to the third sheet portion 143 in which the riblet structure RB is not formed.

[0047] In this way, when the third surface 133 is concave with respect to the first surface 131 and the second surface 132 (specifically, concave with respect to the convex structure 191), the third surface 133 is less likely to act on the fluid as an obstacle that blocks the flow of the fluid flowing along the convex structure 191 between two adjacent convex structures 191, compared to when the third surface 133 is convex with respect to the first surface 131 and the second surface 132. In other words, when the third sheet portion 143 is concave with respect to the first sheet portion 141 and the second sheet portion 142 (specifically, concave with respect to the convex structure 191), the third sheet portion 143 is less likely to act on the fluid as an obstacle that blocks the flow of the fluid flowing along the convex structure 191 between two adjacent convex structures 191, compared to when the third sheet portion 143 is convex with respect to the first sheet portion 141 and the second sheet portion 142. In other words, the third surface 133 (third sheet portion 143) is less likely to act on the fluid as an obstacle blocking the flow of the fluid flowing along the groove structure 192 within the groove structure 192. As a result, as shown in FIGS. 5( a) and 5(b), the flow of the fluid flowing along the convex structures 191 between two adjacent convex structures 191 is less likely to be blocked by the third surface 133 (third sheet portion 143). In other words, the flow of the fluid flowing along the groove structure 192 within the groove structure 192 is less likely to be blocked by the third surface 133 (third sheet portion 143). As a result, in this embodiment, the resistance to the fluid on the surface of the moving body to which the riblet sheet 1 is attached is less likely to increase. In other words, the resistance reduction effect of the riblet structure RB is less likely to deteriorate. As a result, a moving body to which the riblet sheet 1 is attached can fully enjoy the resistance reduction effect of the riblet structure RB.

[0048] Furthermore, the thickness of the third sheet portion 143 (i.e., the size in the Z-axis direction) is thinner than the thicknesses of the first sheet portion 141 and the second sheet portion 142 (thicknesses including the convex structures 191). As a result, the rigidity of the third sheet portion 143 is lower than the rigidity of the first sheet portion 141 and the second sheet portion 142. Alternatively, the rigidity of the riblet sheet 1 may be set so that the rigidity of the third sheet portion 143 is lower than the rigidity of the first sheet portion 141 and the second sheet portion 142. In this case, even if the surface of a moving body (for example, at least one surface of an airplane casing, wing, wind turbine, railway, automobile, etc.) is curved, the third sheet portion 143, which has a relatively low rigidity, is more likely to bend, which may provide the effect that the shape of the riblet sheet 1 is more likely to conform to the shape of the curved surface of the moving body.

[0049] Furthermore, when the riblet sheet 1 is pressed and attached to the surface of a moving body (e.g., at least one surface of an airplane casing, wing, wind turbine, railway, automobile, etc.), the riblet sheet 1 may be attached to the moving body by pressing the third sheet portion 143 with a strong force to obtain sufficient adhesion between the riblet sheet 1 and the surface of the moving body. On the other hand, the first sheet portion 141 and the second sheet portion 142 on which the riblet structure RB is formed do not need to be pressed with a strong force. In other words, the force applied to at least a portion of the third sheet portion 143 to attach the riblet sheet 1 to the moving body may be greater than the force applied to at least a portion of the first sheet portion 141 and the second sheet portion 142 to attach the riblet sheet 1 to the moving body. As a result, deformation or damage to the riblet structure RB formed in the first sheet portion 141 and the second sheet portion 142 can be prevented.

[0050] Furthermore, when wiping the libretto sheet 1 attached to a movable body while the libretto sheet 1 is still attached to the movable body, the dust that has entered the groove structure 192 included in the libretto structure RB may be swept up so that it is guided (in other words, collected) into the third sheet portion 143. After sweeping, the dust that has collected in the third sheet portion 143 is wiped up, thereby completing the cleaning of the libretto sheet 1.

[0051] The height of the third surface 133, which may be referred to as a recess, may be the same as the height of each of the first surface 131 and the second surface 132 (specifically, the height of a boundary portion 1914 that forms the groove structure 192 and is included in each of the first surface 131 and the second surface 132). In other words, along the height direction (Z-axis direction) of the convex structure 191, the position of the third surface 133 is located at the same position as each of the first surface 131 and the second surface 132 (particularly the position of the boundary portion 1914) along the height direction (Z-axis direction) of the convex structure 191. As a result, compared to when the height of the third surface 133 is higher than the height of each of the first surface 131 and the second surface 132, the third surface 133 (third sheet portion 143) is less likely to act on the fluid as an obstacle that blocks the flow of the fluid flowing along the convex structures 191 between two adjacent convex structures 191. In other words, the third surface 133 (third sheet portion 143) is less likely to act on the fluid as an obstacle blocking the flow of the fluid flowing along the groove structure 192 within the groove structure 192. As a result, as shown in FIGS. 5( a) and 5(b), the flow of the fluid flowing along the convex structures 191 between two adjacent convex structures 191 is less likely to be blocked by the third surface 133 (third sheet portion 143). In other words, the flow of the fluid flowing along the groove structure 192 within the groove structure 192 is less likely to be blocked by the third surface 133 (third sheet portion 143). As a result, in this embodiment, the resistance to the fluid on the surface of the moving body to which the riblet sheet 1 is attached is less likely to increase. In other words, the resistance reduction effect of the riblet structure RB is less likely to deteriorate. As a result, a moving body to which the riblet sheet 1 is attached can fully enjoy the resistance reduction effect of the riblet structure RB.

[0052] The width of the third sheet portion 143 (i.e., the size in the Y-axis direction) may be the same as the width of the riblet sheet 1. The width of the third sheet portion 143 is equivalent to the width of the third surface 133. In this case, the third surface 133 may be considered to separate the multiple convex structures 191 formed on the first surface 131 from the multiple convex structures 191 formed on the second surface 132 by the third surface 133 (third sheet portion 143). In this case, at any position along the width direction of the riblet sheet 1 (i.e., the arrangement direction of the convex structures 191, the Y-axis direction), the third surface 133 (third sheet portion 143) is unlikely to act on the fluid as an obstacle that blocks the flow of the fluid. As a result, at any position along the width direction of the riblet sheet 1, the flow of the fluid is unlikely to be blocked by the third surface 133 (third sheet portion 143). As a result, in this embodiment, it is unlikely that the resistance to fluid on the surface of a moving body to which the riblet sheet 1 is attached will be high at any position along the width direction of the riblet sheet 1. In other words, it is unlikely that the resistance reduction effect of the riblet structure RB will be deteriorated at any position along the width direction of the riblet sheet 1. As a result, a moving body to which the riblet sheet 1 is attached can fully enjoy the resistance reduction effect of the riblet structure RB.

[0053] The third surface 133 (third sheet portion 143) may be considered to extend along the width direction of the riblet sheet 1 (i.e., the size in the Y-axis direction). In other words, the third surface 133 (third sheet portion 143) may be considered to extend along the arrangement direction of the convex structures 191 (i.e., the size in the Y-axis direction). In this case, too, the multiple convex structures 191 formed on the first surface 131 and the multiple convex structures 191 formed on the second surface 132 may be considered to be separated by the third surface 133 (third sheet portion 143). As a result, a moving body to which the riblet sheet 1 is attached can fully enjoy the resistance reduction effect of the riblet structure RB.

[0054] In the example shown in Figures 5(a) and 5(b), the boundary portions between the third surface 133 and the first surface 131, and the boundary portions between the third surface 133 and the second surface 132 are angular, but the boundary portions may be rounded.

[0055] (3) Manufacturing Method of Riblet Sheet 1 Next, a manufacturing method of the riblet sheet 1 having the riblet structure RB formed thereon, which can prevent deterioration of the drag reduction effect shown in Figures 5(a) and 5(b), will be described.

[0056] The riblet sheet 1 may be manufactured using a processing device capable of performing removal processing. For example, the processing device may perform removal processing to remove a portion of the riblet sheet 1 (for example, a portion of the coating layer 12) by irradiating processing light onto the riblet sheet 1 on which the riblet structure RB has not yet been formed. In this case, the processing device may perform removal processing to remove a portion of the riblet sheet 1 (typically, a portion of the coating layer 12) so that the riblet structure RB is formed on the surface of the riblet sheet 1.

[0057] However, the riblet sheet 1 may be manufactured by other manufacturing methods.

[0058] (4) Modifications Next, modifications of the riblet sheet 1 will be described.

[0059] 5(a) and 5(b), the height of the third surface 133 on which the riblet structure RB is not formed is the same as the height of each of the first surface 131 and the second surface 132 on which the riblet structure RB is formed (specifically, the height of the boundary portion 1914 which forms the groove structure 192 and is included in each of the first surface 131 and the second surface 132). In other words, along the height direction (Z-axis direction) of the convex structure 191, the position of the third surface 133 is located at the same position as each of the first surface 131 and the second surface 132 (specifically, the position of the boundary portion 1914) along the height direction (Z-axis direction) of the convex structure 191.

[0060] On the other hand, in the riblet sheet 1a of the first modified example, as shown in Figures 6(a) and 6(b), the height of the third surface 133 on which the riblet structure RB is not formed may be lower than the respective heights of the first surface 131 and the second surface 132 on which the riblet structure RB is formed (specifically, the height of the boundary 1914). In other words, along the height direction (Z-axis direction) of the convex structure 191, the position of the third surface 133 may be located on the -Z side (i.e., the opposite side to the +Z side in which the convex structure 191 protrudes) of the respective positions of the first surface 131 and the second surface 132 along the height direction (Z-axis direction) of the convex structure 191 (specifically, the position of the boundary 1914).

[0061] 6( a) and 6(b), the third surface 133 is concave with respect to the first surface 131 and the second surface 132 (specifically, with respect to the boundary portion 1914). That is, the third sheet portion 143 is concave with respect to the first sheet portion 141 and the second sheet portion 142 (specifically, with respect to the boundary portion 1914). Note that each of the first surface 131 and the second surface 132 (specifically, the boundary portion 1914) may be considered to be the bottom surface of the groove structure 192. In this case, the third surface 133 may be considered to be concave with respect to the bottom surface of the groove structure 192 formed on the first surface 131 and the bottom surface of the groove structure 192 formed on the second surface 132.

[0062] However, if the height of the third surface 133 is lower than the height of the adhesive layer 11, the adhesive layer 11 will be exposed from the coating layer 12. For this reason, as shown in Figure 6 (b), the height of the third surface 133 may be higher than the height of the adhesive layer 11. As a result, the adhesive layer 11 will not be exposed from the coating layer 12. Furthermore, if the riblet sheet 1 does not have an adhesive layer 11, the riblet sheet 1 will not tear.

[0063] Even in this case, as shown in FIGS. 6( a) and 6(b), compared to when the height of the third surface 133 is higher than the heights of the first surface 131 and the second surface 132 (specifically, the height of the boundary portion 1914), the third surface 133 (third sheet portion 143) is less likely to act on the fluid as an obstacle that blocks the flow of the fluid flowing along the convex structures 191 between two adjacent convex structures 191. In other words, the third surface 133 (third sheet portion 143) is less likely to act on the fluid as an obstacle that blocks the flow of the fluid flowing along the groove structure 192 within the groove structure 192. As a result, as shown in FIGS. 6( a) and 6(b), the flow of the fluid flowing along the convex structures 191 between two adjacent convex structures 191 is less likely to be blocked by the third surface 133 (third sheet portion 143). In other words, the flow of fluid flowing within and along the groove structure 192 is unlikely to be blocked by the third surface 133 (third sheet portion 143). As a result, in this embodiment, the resistance to fluid on the surface of the moving body to which the riblet sheet 1a is attached is unlikely to increase. In other words, the resistance reduction effect of the riblet structure RB is unlikely to deteriorate. As a result, a moving body to which the riblet sheet 1a is attached can fully enjoy the resistance reduction effect of the riblet structure RB.

[0064] Furthermore, the thickness of the third sheet portion 143 (i.e., the size in the Z-axis direction) is thinner than the thicknesses of the first sheet portion 141 and the second sheet portion 142 (thicknesses including the convex structures 191). As a result, the rigidity of the third sheet portion 143 is lower than the rigidity of the first sheet portion 141 and the second sheet portion 142. Alternatively, the rigidity of the riblet sheet 1a may be set so that the rigidity of the third sheet portion 143 is lower than the rigidity of the first sheet portion 141 and the second sheet portion 142. In this case, even if the surface of a moving body (for example, at least one surface of an airplane casing, wing, wind turbine, railway, automobile, etc.) is curved, the third sheet portion 143, which has a relatively low rigidity, is more likely to bend, which may provide the effect of making it easier for the shape of the riblet sheet 1a to conform to the shape of the curved surface of the moving body.

[0065] Furthermore, when the riblet sheet 1a is pressed and attached to the surface of a moving body (e.g., at least one surface of an airplane casing, wing, wind turbine, railway, automobile, etc.), the riblet sheet 1a may be attached to the moving body by pressing the third sheet portion 143 with a strong force to obtain sufficient adhesion between the riblet sheet 1a and the surface of the moving body. On the other hand, the first sheet portion 141 and the second sheet portion 142 on which the riblet structure RB is formed do not need to be pressed with a strong force. In other words, the force applied to at least a portion of the third sheet portion 143 to attach the riblet sheet 1a to the moving body may be greater than the force applied to at least a portion of the first sheet portion 141 and the second sheet portion 142 to attach the riblet sheet 1a to the moving body. As a result, deformation or damage to the riblet structure RB formed in the first sheet portion 141 and the second sheet portion 142 can be prevented.

[0066] Furthermore, when wiping the libretto sheet 1a attached to a movable body while the libretto sheet 1a remains attached to the movable body, the dust that has entered the groove structure 192 included in the libretto structure RB may be swept up so that it is guided (in other words, collected) into the third sheet portion 143. After sweeping, the dust that has collected in the third sheet portion 143 is wiped up, thereby completing the cleaning of the libretto sheet 1a.

[0067] The riblet sheet 1a of the first modified example shown in Figures 6(a) and 6(b) may also be manufactured using a processing device. The riblet sheet 1a of the first modified example shown in Figures 6(a) and 6(b) may also be manufactured by a manufacturing method different from the manufacturing method using a processing device.

[0068] (4-2) Second Modified Example In the above description, the riblet structure surface 130 of the riblet sheet 1 includes two surfaces (specifically, a first surface 131 and a second surface 132) on which the same riblet structure RB (or, in some cases, different riblet structures RB; hereinafter, the same applies in the second modified example) is formed. On the other hand, the riblet structure surface 130 of the riblet sheet 1b of the second modified example may include three or more surfaces on which the same riblet structure RB is formed.

[0069] For example, as shown in Figure 7, which shows an example of a riblet structure RB formed on the riblet sheet 1 of the second modified example, the riblet structure surface 130 of the riblet sheet 1b of the second modified example may include a fourth surface 134 and a fifth surface 135 in addition to the first surface 131, second surface 132, and third surface 133 described above.

[0070] A part of the riblet structure RB may be formed on the fourth surface 134, similar to the first surface 131 and the second surface 132. The features of the fourth surface 134 may be the same as the features of the first surface 131 and the second surface 132. Therefore, a detailed description of the fourth surface 134 will be omitted. Note that a part of the riblet sheet 1b including the fourth surface 134 may be referred to as a fourth sheet portion (in other words, a fourth portion or a fourth region) 144.

[0071] The fifth surface 135 is located between the second surface 132 and the fourth surface 134 along the extension direction of the riblet structure RB. Like the third surface 133, the fifth surface 135 does not need to have a riblet structure RB formed thereon. The characteristics of the fifth surface 135 may be the same as the characteristics of the third surface 133. The relationship between the fifth surface 135 and the second surface 132 and the fourth surface 134 between which the fifth surface 135 is located may be the same as the relationship between the third surface 133 and the first surface 131 and the second surface 132 between which the third surface 133 is located. For this reason, a detailed description of the fifth surface 135 will be omitted. Note that a portion of the riblet sheet 1b including the fifth surface 135 may be referred to as a fifth sheet portion (in other words, a fifth portion or a fifth region) 145.

[0072] Here, each of the first surface 131, the second surface 132, and the fourth surface 134 on which the riblet structure RB is formed may be referred to as a riblet surface 136. Each of the third surface 133 and the fifth surface 135 on which the riblet structure RB is not formed may be referred to as a non-riblet surface 137. In this case, the riblet structure surface 130 may be considered to include a surface on which the riblet surfaces 136 on which the riblet structure RB is formed and the non-riblet surfaces 137 on which the riblet structure RB is not formed are alternately arranged along the extension direction of the riblet structure RB (X-axis direction). The riblet structure surface 130 may be considered to include a surface on which the riblet surfaces 136 on which the riblet structure RB is formed are periodically arranged. The riblet structure surface 130 may be considered to include a riblet surface 136 arranged between two non-riblet surfaces 137 aligned along the extension direction of the riblet structure RB. The riblet structure surface 130 may be considered to include a non-riblet surface 137 arranged between two riblet surfaces 136 aligned along the extension direction of the riblet structure RB.

[0073] The riblet sheet 1b of the second modified example shown in Fig. 7 may also be manufactured using a processing device. The riblet sheet 1b of the second modified example shown in Fig. 7 may also be manufactured by a manufacturing method different from the manufacturing method using a processing device.

[0074] (4-3) Third Modification In the above description, the convex structures 191 constituting the riblet structure RB extend linearly along the extension direction. In other words, the groove structures 192 constituting the riblet structure RB extend linearly along the extension direction.

[0075] On the other hand, in the riblet sheet 1c of the third modified example, as shown in Fig. 8 which schematically shows the riblet structure RB formed on the riblet sheet 1c, the riblet structure RB may include a convex structure 191 that extends in a curved shape. In other words, the riblet structure RB may include a groove structure 192 that extends in a curved shape.

[0076] 8, the riblet structure RB may include a convex structure 191 extending along a curved locus (e.g., a sinusoidal locus) that vibrates at a predetermined frequency around an axis extending along the stretching direction. In other words, the riblet structure RB may include a groove structure 192 extending along a curved locus (e.g., a sinusoidal locus) that vibrates at a predetermined frequency around an axis extending along the stretching direction.

[0077] (5) Supplementary Notes The following supplementary notes are added to the above-described embodiment. [Supplementary Note 1] A film-like sheet member on which a riblet structure having a plurality of groove structures is formed, wherein the plurality of groove structures include: a first group of groove structures in which a plurality of first groove structures extending in a first direction along the surface of the sheet member are formed in a second direction intersecting the first direction; and a second group of groove structures in which a plurality of second groove structures extending in a third direction along the surface of the sheet member are formed in a fourth direction intersecting the third direction, wherein a region between a region in which the first group of groove structures is formed and a region in which the second group of groove structures is formed in at least one of the first direction and the third direction is concave with respect to bottom surfaces of the first and second groove structures. [Supplementary Note 2] The sheet member according to Supplementary Note 1, wherein the first direction and the third direction are the same direction, and the second direction and the fourth direction are the same direction.

[0078] 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.

[0079] 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 seat members and moving bodies that involve such modifications are also included in the technical idea of ​​the present invention.

[0080] REFERENCE SIGNS LIST 1 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

Claims

1. A film-like sheet member having a riblet structure formed on its surface, The sheet member is The first page and The second side and a third surface located between the first surface and the second surface; and Equipped with On the first surface, as part of the riblet structure, a plurality of first convex structures are formed, the first convex structures extending in a first direction in which the first to third surfaces are aligned and protruding from the first surface in a second direction intersecting with the first direction, the first convex structures being aligned along the first to third surfaces and aligned in a third direction intersecting with the first and second directions, A plurality of second convex structures extending in the first direction and protruding from the second surface in the second direction are formed on the second surface as part of the riblet structure so as to be aligned in the third direction, The third surface is concave relative to the first and second surfaces. Sheet member.

2. The third surface does not have a convex structure. The sheet member according to claim 1 .

3. The first surface and the second surface have the same riblet structure. The sheet member according to claim 2 .

4. The riblet structure of the first surface is the same as that of the first surface. The sheet member according to claim 1 .

5. A surface having the same riblet structure as the riblet structure of the first surface is provided periodically in the first direction. The sheet member according to claim 1 .

6. each of the plurality of first convex structures protrudes from the first surface toward one side along the second direction; each of the plurality of second convex structures protrudes from the second surface toward the one side along the second direction; The third surface is located at the same position as each of the first and second surfaces along the second direction, or is located on the other side of the first and second surfaces along the second direction, opposite to the one side. The sheet member according to claim 1 .

7. The surface of the sheet member is The fourth side, a fifth surface located between the second surface and the fourth surface; and Equipped with On the fourth surface, as the riblet structure, a plurality of third convex structures extending along the first direction and protruding from the fourth surface along the second direction are formed so as to be aligned along the third direction, The fifth surface is concave relative to the second and fourth surfaces. The sheet member according to claim 1 .

8. each of the plurality of second convex structures protrudes from the second surface toward one side along the second direction; each of the plurality of third convex structures protrudes from the fourth surface toward the one side along the second direction, The position of the fifth surface along the second direction is located at the same position as each of the second and fourth surfaces along the second direction, or is located on the other side opposite to the one side along the second direction with respect to each of the second and fourth surfaces along the second direction. The sheet member according to claim 7.

9. the sheet member includes a first layer and a second layer formed on the first layer; The height of the third surface is higher than the height of the surface of the first layer. The sheet member according to claim 1 .

10. The first layer includes an adhesive layer including an adhesive material for attaching the second layer to an object. The sheet member according to claim 9.

11. The second layer includes a coating layer including a paint that covers the surface of the object. The sheet member according to claim 9.

12. The second layer includes a coating layer that protects the surface of the paint layer. The sheet member according to claim 11.

13. A moving body having the sheet member according to any one of claims 1 to 12 attached to at least a part of its surface.

14. the movable body is movable through a fluid, The riblet structure formed on the surface of the sheet member can reduce the resistance of the moving body moving relative to the fluid. The moving body according to claim 13.

15. The moving object includes at least one of a railway vehicle, an automobile, an aircraft, and a wind turbine. The moving body according to claim 14.

16. A film-like sheet member having a riblet structure formed on its surface, The sheet member is The first page and The second side and a third surface located between the first surface and the second surface; and Equipped with On the first surface, as part of the riblet structure, a plurality of first convex structures protruding from the first surface in a second direction intersecting a first direction in which the first to third surfaces are aligned are formed so as to be aligned in a third direction intersecting the first and second directions, A plurality of second convex structures protruding from the second surface in the second direction are formed on the second surface as part of the riblet structure and aligned in the third direction, The third surface is concave relative to the first and second surfaces. Sheet member.

17. A moving body having the sheet member according to claim 16 attached to at least a part of its surface.

18. A film-like sheet member having a riblet structure having a plurality of groove structures, The plurality of groove structures include: a first group of groove structures, each of which includes a first groove structure extending in a first direction along a surface of the sheet member and a second groove structure extending in a second direction intersecting the first direction; a second group of groove structures, each of which extends in a third direction along the surface of the sheet member and is formed in a fourth direction intersecting the third direction; Equipped with A region between the region where the first group of groove structures is formed and the region where the second group of groove structures is formed in at least one of the first direction and the third direction is recessed with respect to bottom surfaces of the first and second groove structures. Sheet member.

19. The first direction and the third direction are the same direction, The second direction and the fourth direction are the same direction. The sheet member according to claim 18