Structure and object having the same

Abstract

To provide a structure which can reduce a pressure resistance received by an object from a fluid.SOLUTION: A structure for reducing a resistance of a fluid includes: a first face in contact with the fluid; a friction part 25 positioned on the first face and expanding in a facial first direction along the first face; and a first smooth part positioned on the first face and adjacent to the friction part 25 in a facial second direction that crosses with the facial first direction. The friction part 25 includes a plurality of first guide structures 31 aligned in the facial first direction and guiding the fluid toward the first smooth part. The first guide structure 31 includes a first end part extending toward the first smooth part. The first end part has a first inclination angle of over 0° to less than 90° with respect to the facial first direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present disclosure relate to structures and objects comprising structures for reducing fluid resistance. [Background technology]

[0002] When a fluid flows along an object, a boundary layer is formed between the object's surface and the fluid. In the boundary layer, the fluid is subjected to frictional forces from the object's surface due to viscosity. If the frictional force becomes large, the fluid may separate from the object's surface, forming a dead water region between the fluid and the object's surface. This phenomenon is called separation. When separation occurs, the pressure resistance that the object experiences from the fluid increases.

[0003] A known method for suppressing separation is to install a member that generates vortices on the surface of an object to promote mixing of the fluid. For example, Patent Document 1 proposes installing a structure including a rough surface with uniformly distributed asperities on the surface of the object. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-57390 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of an embodiment of the present disclosure is to provide a structure that can reduce the pressure resistance that an object experiences from a fluid. [Means for solving the problem]

[0006] The embodiments of the present disclosure relate to the following [1] to

[20] . [1] A structure for reducing fluid resistance, a first surface in contact with the fluid; a friction portion located on the first surface and extending in a first direction along the first surface; a first smooth portion located on the first surface and adjacent to the friction portion in a second surface direction intersecting the first surface direction, the friction portion includes a plurality of first guide structures aligned in the first direction of the surface and configured to guide a fluid to the first smooth portion; the first guide structure includes a first end portion extending toward the first smooth portion; The first end portion has a first tilt angle greater than 0° and less than 90° relative to the first surface direction. The friction portion may have a length of 50 mm or more and 1000 mm or less in the first direction of the surface.

[0007] [2] The structure described in [1] may include a second smooth portion located on the first surface and adjacent to the friction portion in the surface second direction. The friction portion is located between the first smooth portion and the second smooth portion in the surface second direction. The friction portion may include a plurality of second guide structures aligned in the surface first direction and guiding a fluid to the second smooth portion, and the second guide structures may include a second end portion extending toward the second smooth portion, and the second end portion may have a second inclination angle greater than 0° and less than 90° with respect to the surface first direction.

[0008] [3] In the structure described in [2], the friction portion may include a connection portion that connects the first guide structure and the second guide structure.

[0009] [4] In the structure described in any one of [1] to [3], the first surface may include a base surface, the first guide structure may protrude from the base surface in a thickness direction of the structure, the first guide structure may have a first height from the base surface, the first height may be 20 μm or more and 400 μm or less, the ratio of the spacing between two of the first guide structures aligned in the first direction of the surface to the first height may be 1.0 or more and 9.0 or less, and the ratio of the dimension of the first guide structure in the first direction of the surface to the first height may be 0.3 or more and 3.0 or less.

[0010] [5] In the structure according to any one of [1] to [4], the friction portion may have a width of 0.2 mm or more and 50 mm or less in a direction perpendicular to the first surface direction.

[0011] [6] In the structure described in any one of [1] to [5], the first surface may include a base surface, and the first guide structure may protrude from the base surface in the thickness direction of the structure.

[0012] [7] In the structure described in [6], the first guide structure may have a first height from the base surface, and the first height may be 20 μm or more and 1.0 mm or less.

[0013] [8] In the structure described in [7], the ratio of the spacing between the multiple first guide structures in a direction perpendicular to the direction in which the first guide structures extend to the first height may be greater than or equal to 1.0 and less than or equal to 12.0.

[0014] [9] In the structure described in any one of [1] to [5], the first surface may include a base surface, and the first guide structure may be recessed relative to the base surface in the thickness direction of the structure.

[0015]

[10] In the structure described in any one of [6] to [9], the friction portion may include the base surface at a first base ratio, and the first smooth portion may include the base surface at a second base ratio higher than the first base ratio.

[0016]

[11] In the structure according to any one of [1] to

[10] , the first tilt angle may be 15° or more and 75° or less.

[0017]

[12] In the structure according to any one of [1] to

[11] , the first guide structure may extend linearly toward the first smooth portion.

[0018]

[13] In the structure described in

[12] , the first guide structure may have a deviation distance of 0.1 mm or less. The deviation distance is the maximum distance in the first plane direction between a first virtual line and the first guide structure. The first virtual line is a line passing through a portion of the first guide structure located most upstream in the first plane direction and a portion of the first guide structure located most downstream in the first plane direction.

[0019]

[14] In the structure described in any one of [1] to

[13] , the first surface may include a curved surface, and the friction portion and the first smooth portion may be located on the curved surface.

[0020]

[15] In the structure described in

[14] , a boundary line between the friction portion and the first smooth portion may extend parallel to the first surface direction.

[0021]

[16] An object in contact with a fluid, The object includes the structure according to any one of [1] to

[15] , which is located on a surface of the object.

[0022]

[17] In the object described in

[16] , the object may have a curved portion, and the structure may be located in the curved portion.

[0023]

[18] An object in contact with a fluid, An object comprising a part made of the structure according to any one of [1] to

[15] .

[0024]

[19] The object according to any one of

[16] to

[18] may be a moving object or a part of a moving object.

[0025]

[20] The object according to any one of

[16] to

[18] may be an object for controlling the flow of a fluid.

[0026] According to the embodiments of the present disclosure, the pressure resistance that an object experiences from a fluid can be reduced. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a side view of a first embodiment of an object. [Figure 2] FIG. 1 is a plan view showing a first embodiment of an object. [Figure 3] FIG. 1 is a diagram illustrating an example of a structure attached to an object. [Figure 4] FIG. 2 is a plan view showing an example of a structure. [Figure 5A] FIG. 5 is an enlarged plan view showing the structure of FIG. 4. [Figure 5B] FIG. 10 is a plan view showing a modified example of the structure. [Figure 6A] 6 is a cross-sectional view showing the structure of FIG. 4 as viewed from the VI-VI direction. [Figure 6B] FIG. 10 is a cross-sectional view showing a modified example of the structure. [Figure 6C] FIG. 1 is a cross-sectional view showing an example of a structure before being attached to an object. [Figure 7] FIG. 10 is a diagram showing an example of a vortex generated in a structure. [Figure 8] FIG. 2 is a diagram showing an example of a state of a fluid flowing along the surface of an object according to the first embodiment. [Figure 9]FIG. 10 is a diagram showing an example of a state of a fluid flowing along the surface of an object in a comparative example. [Figure 10] FIG. 10 is a cross-sectional view showing a modified example of the structure. [Figure 11A] FIG. 10 is a plan view showing a modified example of the disturbance structure. [Figure 11B] FIG. 10 is a plan view showing a modified example of the disturbance structure. [Figure 12] FIG. 10 is a plan view showing a modified example of the disturbance structure. [Figure 13] FIG. 10 is a plan view showing a modified example of the disturbance structure. [Figure 14A] FIG. 10 is a plan view showing a modified example of the disturbance structure. [Figure 14B] FIG. 10 is a plan view showing a modified example of the disturbance structure. [Figure 15A] FIG. 10 is a plan view showing a modified example of the disturbance structure. [Figure 15B] FIG. 10 is a plan view showing a modified example of the disturbance structure. [Figure 16] FIG. 10 is a plan view showing a modified example of the disturbance structure. [Figure 17] FIG. 10 is a plan view showing a modified example of the structure. [Figure 18] FIG. 10 is a side view showing a modified example of the object. [Figure 19] FIG. 10 is a side view showing a modified example of the object. [Figure 20] 1 is a table showing the evaluation results of Examples A1 to A5 and Comparative Examples A1 to A2. [Figure 21] 1 is a table showing the evaluation results of Examples A11 to A15 and Comparative Example A11. [Figure 22] 1 is a graph showing the evaluation results of Examples A11 to A13 and Comparative Example A11. [Figure 23] 1 is a graph showing the evaluation results of Examples A14 to A16 and Comparative Example A11. [Figure 24] 1 is a table showing the evaluation results of Examples A21 to A28. [Figure 25] 1 is a graph showing the evaluation results of Examples A21 to A26 and Comparative Example A11. [Figure 26]1 is a graph showing the evaluation results of Examples A27 to A28 and Comparative Example A11. [Figure 27] FIG. 10 is a side view of a second embodiment of the object. [Figure 28] FIG. 10 is a plan view showing a second embodiment of the object. [Figure 29] FIG. 1 is a perspective view showing an example of a structure attached to an object. [Figure 30] FIG. 30 is an enlarged view of the structure of FIG. 29. [Figure 31] FIG. 2 is a plan view showing an example of a structure. [Figure 32A] 32 is a cross-sectional view showing the structure of FIG. 31 as viewed from the XXXII-XXXII direction. [Figure 32B] FIG. 10 is a cross-sectional view showing a modified example of the structure. [Figure 32C] FIG. 1 is a diagram illustrating an example of the MD direction of a structure. [Figure 32D] 10A and 10B are diagrams for explaining a method for measuring the positions and shapes of components of a friction portion. [Figure 33] FIG. 10 is a diagram showing an example of a vortex generated in a structure. [Figure 34] FIG. 10 is a diagram showing an example of a state of a fluid flowing along the surface of an object according to the second embodiment. [Figure 35] FIG. 10 is a diagram showing an example of a state of a fluid flowing along the surface of an object in a comparative example. [Figure 36] FIG. 10 is a cross-sectional view showing a modified example of the structure. [Figure 37A] FIG. 10 is a plan view showing a modified example of the structure. [Figure 37B] FIG. 10 is a plan view showing a modified example of the structure. [Figure 38A] FIG. 10 is a plan view showing a modified example of the structure. [Figure 38B] FIG. 4 is a diagram for explaining a method for measuring a first arithmetic mean height and a first maximum height of a friction portion. [Figure 38C] FIG. 4 is a diagram for explaining a method for measuring a first arithmetic mean height and a first maximum height of a friction portion. [Figure 39]FIG. 10 is a plan view showing a modified example of the structure. [Figure 40A] FIG. 10 is a plan view showing a modified example of the structure. [Figure 40B] FIG. 40B is a diagram showing an example of a vortex generated in the structure of FIG. 40A. [Figure 41A] FIG. 10 is a plan view showing a modified example of the structure. [Figure 41B] FIG. 41B is a diagram showing an example of a vortex generated in the structure of FIG. 41A. [Figure 42] FIG. 10 is a plan view showing a modified example of the structure. [Figure 43] FIG. 10 is a plan view showing a modified example of the structure. [Figure 44] FIG. 10 is a plan view showing a modified example of the object. [Figure 45] FIG. 10 is a side view showing a modified example of the object. [Figure 46] FIG. 10 is a side view showing a modified example of the object. [Figure 47] FIG. 10 is a side view showing a modified example of the object. [Figure 48] FIG. 10 is a perspective view showing a modified example of the object. [Figure 49] FIG. 10 is a perspective view showing a modified example of the object. [Figure 50] 1 is a table showing the evaluation results of Examples B1 to B3 and Comparative Example B1. [Figure 51] 1 is a graph showing the evaluation results of Examples B1 to B3 and Comparative Example B1. [Figure 52] 1 is a table showing the evaluation results of Examples B11 to B16 and Comparative Examples B11 to B12. [Figure 53] 1 is a graph showing the evaluation results of Examples B11 to B16 and Comparative Examples B11 to B12. [Figure 54] 1 is a table showing the evaluation results of Examples B21 to B23. [Figure 55] 1 is a graph showing the evaluation results of Examples B21 to B23. [Figure 56] 1 is a table showing the evaluation results of Example B31 and Comparative Examples B31 and B32. [Figure 57]1 is a graph showing the evaluation results of Example B31 and Comparative Examples B31 and B32. [Figure 58] 10 is a table showing the evaluation results of Examples B41 to B51. [Figure 59] 10 is a graph showing the evaluation results of Examples B41 to B45 and Example B51. [Figure 60] 10 is a table showing the evaluation results of Examples B46 to B48 and Example B51. [Figure 61] 10 is a graph showing the evaluation results of Example B41 and Examples B49 to B51. DETAILED DESCRIPTION OF THE INVENTION

[0028] The configuration of a structure 20 and an object 10 including the structure 20 according to an embodiment of the present disclosure will be described in detail below with reference to the drawings. Note that the first embodiment described below is an example of an embodiment of the present disclosure, and the present disclosure should not be construed as being limited to these embodiments. Terms used in this specification that specify shapes, geometric conditions, and their degrees, such as "parallel" and "orthogonal," and values ​​of lengths and angles, are not limited to their strict meanings and are interpreted to include a range within which similar functions can be expected.

[0029] In this specification, when multiple upper limit candidates and multiple lower limit candidate values ​​are listed for a certain parameter, the numerical range of the parameter may be constructed by combining any one upper limit candidate with any one lower limit candidate. For example, consider a description that reads, "Parameter B is, for example, A1 or more, or may be A2 or more, or may be A3 or more. Parameter B is, for example, A4 or less, or may be A5 or less, or may be A6 or less." In this case, the numerical range of parameter B may be A1 or more and A4 or less, A1 or more and A5 or less, A1 or more and A6 or less, A2 or more and A4 or less, A2 or more and A5 or less, A2 or more and A6 or less, A3 or more and A4 or less, A3 or more and A5 or less, or A3 or more and A6 or less.

[0030] In the drawings referred to in this disclosure, identical or similar reference numerals are used to designate identical or similarly functional parts, and repeated explanations of such parts may be omitted. In addition, the dimensional ratios of the drawings may differ from the actual ratios for the sake of explanation, and some components may be omitted from the drawings.

[0031] A first embodiment of the present disclosure will be described in detail with reference to the drawings. The first embodiment described below is an example of an embodiment of the present disclosure, and the present disclosure should not be interpreted as being limited to only these embodiments.

[0032] The first embodiment relates to a structure that comes into contact with a fluid. A structure that includes a rough surface has the advantage of reducing the pressure resistance that an object experiences from a fluid, but can also have the disadvantage of increasing the friction resistance that the fluid experiences from the structure.

[0033] The first embodiment has been made in consideration of these points, and aims to provide a structure that can reduce the pressure resistance that an object experiences from a fluid while reducing the friction resistance that a fluid experiences from the structure.

[0034] Fig. 1 is a side view showing an example of an object 10. Fig. 2 is a plan view showing an example of an object 10. As shown in Figs. 1 and 2, the object 10 may be a moving object such as a bus.

[0035] The object 10 may include a front surface 11 and a rear surface 12. The front surface 11 is the surface of the object 10 located upstream in the flow direction of the fluid F. The fluid F collides with the front surface 11. The rear surface 12 is the surface of the object 10 located downstream in the flow direction of the fluid F. The rear surface 12 is located opposite the front surface 11 in the flow direction of the fluid F.

[0036] The flow direction of the fluid F is the relative movement direction of the fluid F with respect to the object 10. In the example shown in Figures 1 and 2, a situation is assumed in which the object 10 moves forward. The flow direction of the fluid F is also referred to as the first direction and is represented by the symbol D1. The symbols D2 and D3 represent the second direction and the third direction, respectively. The second direction D2 and the third direction D3 are each perpendicular to the first direction D1. Furthermore, the second direction D2 and the third direction D3 are perpendicular to each other. In the example shown in Figures 1 and 2, the second direction D2 is a direction perpendicular to the first direction D1 and along a horizontal plane, and the third direction D3 is a direction perpendicular to the first direction D1 and along a vertical plane.

[0037] The object 10 includes a side surface 14 extending from a front surface 11 to a rear surface 12. A fluid F flows downstream along the side surface 14. The side surface defining the top end of the object 10 is also referred to as an upper surface 13.

[0038] As shown in Figures 1 and 2, the object 10 includes a structure 20 attached to a rear surface 12. The structure 20 may be attached to an inclined portion of the rear surface 12. The inclination angle θ of the inclined portion of the rear surface 12 is, for example, 30° or more, or may be 40° or more, or 50° or more. The inclination angle θ is, for example, 80° or less, or may be 70° or less, or may be 60° or less. The inclination angle θ is the angle between the direction in which the inclined portion of the rear surface 12 widens and the first direction D1.

[0039] The structure 20 is configured to generate vortices to promote mixing of the fluid. By attaching the structure 20 to the object 10, separation of the fluid F from the object 10 can be suppressed.

[0040] 2, the object 10 includes a front window 161 and a rear window 162. The structure 20 may be attached to the rear window 162.

[0041] The structure 20 includes a first surface 21 that contacts the fluid F. The first surface 21 may include a flat region. The first surface 21 may include a curved region.

[0042] In this embodiment, the structure 20 is flexible. Therefore, the structure 20 attached to the object 10 deforms according to the shape of the object 10. For example, when the structure 20 is attached to a curved portion of the object 10, a curved surface may also be generated in the first surface 21 of the structure 20.

[0043] 3 is a perspective view showing an example of a structure 20 attached to an object 10. The structure 20 extends along a first surface direction E1, which is one of the surface directions of the surface of the object 10. The first surface direction E1 may be parallel to the direction in which the first direction D1 is projected onto the surface of the object 10.

[0044] As shown in FIG. 3, the structure 20 includes a friction portion 25 and a smooth portion 26 located on the first surface 21. The friction portion 25 and the smooth portion 26 extend in a first surface direction E1. The smooth portion 26 is adjacent to the friction portion 25 in a second surface direction E2. The second surface direction E2 is a direction along the first surface 21 and intersects with the first surface direction E1. The second surface direction E2 may be perpendicular to the first surface direction E1. As shown in FIG. 3, a plurality of friction portions 25 and smooth portions 26 may be arranged alternately along the second surface direction E2.

[0045] 3, the dotted line denoted by the reference numeral 27 indicates the boundary between the friction portion 25 and the smooth portion 26. The imaginary line indicating the boundary is also referred to as the boundary line. The boundary line 27 extends parallel to the first planar direction E1.

[0046] 4 is a plan view showing the structure 20 based on a coordinate system of a first planar direction E1 and a second planar direction E2. The friction portion 25 is configured to disturb the flow of the fluid F. For example, the resistance experienced by the fluid F when it flows along the friction portion 25 is greater than the resistance experienced by the fluid F when it flows along the smooth portion 26. As a result, a flow deviating from the first direction D1 can be generated at the boundary between the friction portion 25 and the smooth portion 26. For example, a vortex can be generated in the fluid F at the boundary between the friction portion 25 and the smooth portion 26.

[0047] As shown in Fig. 4, the friction portion 25 may include a plurality of disturbance structures 30 that disturb the flow of the fluid F. The plurality of disturbance structures 30 may be aligned in the first planar direction E1. As shown in Fig. 5A, the disturbance structures 30 include ends that contact the smooth portion 26. A boundary line 27 is defined as a line passing through the ends of the plurality of disturbance structures 30.

[0048] In FIG. 4, symbol S1 represents the dimension of the friction portion 25 in the first planar direction E1. The dimension S1 is also referred to as the length S1. The length S1 may be set so that a sufficient number of disturbance structures 30 are aligned in the first planar direction E1. The length S1 may be, for example, 5 mm or more, 10 mm or more, 25 mm or more, 30 mm or more, 50 mm or more, or 100 mm or more. This allows the fluid F flowing along the friction portion 25 to be repeatedly disturbed by the multiple disturbance structures 30. This promotes mixing of the fluid in the boundary layer between the fluid F and the surface of the object 10. This prevents fluid separation.

[0049] On the other hand, if the length S1 becomes too large, the frictional resistance that the fluid F receives from the structure 20 increases, hindering the flow of the fluid F. In consideration of this point, the length S1 is, for example, 1000 mm or less, or may be 500 mm or less, or may be 200 mm or less.

[0050] The length S1 of the friction portion 25 is determined based on the disturbance structure 30 located most upstream and the disturbance structure 30 located most downstream in the flow direction of the fluid F, as shown in FIG. 5A.

[0051] The length of the smooth portion 26 in the first surface direction E1 may be the same as or different from the length S1 of the friction portion 25. The numerical range of the length of the smooth portion 26 may be the same as or different from the above-mentioned numerical range of the length S1.

[0052] 4, the symbol S21 represents the dimension of the friction portion 25 in the second planar direction E2. The dimension S21 is also referred to as the width S21. The width S21 may be set so that the friction portion 25 can sufficiently disrupt the flow of the fluid F. The width S21 is, for example, 0.2 mm or more, or may be 1.0 mm or more, or 5.0 mm or more.

[0053] On the other hand, if the width S21 becomes too large, the ratio of the size of the vortex generated at the boundary between the friction portion 25 and the smooth portion 26 to the width S21 becomes small. As a result, the ratio of the fluid F that is less affected by the vortex increases. In consideration of this point, the width S21 is, for example, 50 mm or less, and may be 30 mm or less, or 25 mm or less.

[0054] Although not shown, the width S21 of the friction portion 25 may be greater than the length S1 of the friction portion 25. In other words, the length S1 of the friction portion 25 may be less than the width S21 of the friction portion 25. When the structure 20 has a form that allows it to be attached to the object 10, the efficiency of the attachment work can be improved by reducing the length S1 of the friction portion 25.

[0055] The width S22 of the smooth portion 26 in the second surface direction E2 may be the same as or different from the width S21 of the friction portion 25. The numerical range of the width S22 of the smooth portion 26 may be the same as or different from the above-mentioned numerical range of the width S21 of the friction portion 25.

[0056] As described above, one of the reasons why vortices occur at the boundary between the friction portion 25 and the smooth portion 26 is the difference between the resistance that the fluid F experiences in the friction portion 25 and the resistance that the fluid F experiences in the smooth portion 26. As the width S22 of the smooth portion 26 increases, the flow of the fluid F in the smooth portion 26 is promoted, and the resistance that the fluid F experiences in the smooth portion 26 decreases. As the resistance in the smooth portion 26 decreases, the difference between the resistance in the friction portion 25 and the resistance in the smooth portion 26 increases, promoting the generation of vortices. It is preferable that the ratio of the width S22 of the smooth portion 26 to the width S21 of the friction portion 25 be equal to or greater than a certain value. The ratio S22 / S21 of the width S22 of the smooth portion 26 to the width S21 of the friction portion 25 is, for example, 0.20 or more, or may be 0.50 or more, or may be 1.00 or more. S22 / S21 is, for example, 3.00 or less, or may be 2.50 or less, or may be 2.00 or less. The width S22 of the smooth portion 26 is, for example, 0.2 mm or more, and may be 1.2 mm or more, 2.0 mm or more, or 5.0 mm or more. The width S22 of the smooth portion 26 is, for example, 50 mm or less, and may be 30 mm or less, 25 mm or less, or 20 mm or less.

[0057] As shown in Fig. 4, the disturbance structure 30 includes a first guiding structure 31 and a second guiding structure 32. Fig. 5A is an enlarged plan view of the disturbance structure 30. The first guiding structure 31 and the second guiding structure 32 are aligned in the second planar direction E2. The disturbance structure 30 may include a connecting portion 33 connecting the first guiding structure 31 and the second guiding structure 32.

[0058] As shown in FIG. 5A , the two smooth portions 26 in contact with the friction portion 25 are also referred to as the first smooth portion 26A and the second smooth portion 26B. The friction portion 25 is located between the first smooth portion 26A and the second smooth portion 26B in the second planar direction E2. The first guide structure 31 is configured to guide the fluid F to the first smooth portion 26A, thereby promoting the generation of vortices at the boundary between the friction portion 25 and the first smooth portion 26A. The second guide structure 32 is configured to guide the fluid F to the second smooth portion 26B, thereby promoting the generation of vortices at the boundary between the friction portion 25 and the second smooth portion 26B.

[0059] The structure of the first guide structure 31 will be described. As shown in FIG. 5A, the first guide structure 31 includes a first end portion 311 adjacent to the first smooth portion 26A. The first end portion 311 is a portion of the first guide structure 31 adjacent to the first smooth portion 26A and having a dimension K in the second planar direction E2. The dimension K is 10% of the width S21 described above.

[0060] The first end portion 311 extends toward the first smooth portion 26A in a direction inclined with respect to the first planar direction E1. The angle that the first end portion 311 forms with respect to the first planar direction E1 is also referred to as the first inclination angle and is represented by the symbol φ1. The first inclination angle φ1 is less than 90°. Therefore, the first guide structure 31 can impart a velocity component toward the first smooth portion 26A to the fluid F that collides with the first guide structure 31.

[0061] The first inclination angle φ1 is, for example, greater than 0° and may be 15° or greater, or 30° or greater. The first inclination angle φ1 is, for example, less than 90° and may be 75° or less, or 60° or less. When the first inclination angle φ1 is 15° or greater and 75° or less, the force of the fluid F toward the first smooth portion 26A can be approximately 25% or greater of the total force of the fluid F. When the first inclination angle φ1 is 30° or greater and 60° or less, the force of the fluid F toward the first smooth portion 26A can be approximately 50% or greater of the total force of the fluid F. The force of the fluid F toward the first smooth portion 26A is proportional to the product of sinφ1 and cosφ1.

[0062] 5A, the first guide structure 31 includes a first upstream surface 313 and a first downstream surface 314. The first upstream surface 313 is a side surface of the first guide structure 31 located on the upstream side in the planar first direction E1. The first downstream surface 314 is a side surface of the first guide structure 31 located on the downstream side in the planar first direction E1. The first inclination angle φ1 is the angle formed by the intersection line between the first upstream surface 313 of the first end portion 311 and a base surface 21B (described later) with respect to the planar first direction E1.

[0063] 5A, the first guide structure 31 may extend linearly toward the first smooth portion 26A. For example, an end of the first upstream surface 313 of the first guide structure 31 may extend toward the first smooth portion 26A at a first inclination angle φ1 in a plan view. This allows the fluid F that collides with the first guide structure 31 to be efficiently guided toward the first smooth portion 26A. The symbol K1 represents the dimension in the second planar direction E2 of the portion of the first guide structure 31 that extends linearly toward the first smooth portion 26A. K1 / S21, which is the ratio of the dimension K1 to the width S21, is, for example, 0.20 or more, or may be 0.30 or more, or may be 0.40 or more.

[0064] The entire first guide structure 31 may extend linearly from the connection portion 33 toward the first smooth portion 26A. For example, the first guide structure 31 may have a deviation distance of 0.1 mm or less. The deviation distance is the maximum distance in the planar first direction E1 between the first imaginary straight line L1 and the first guide structure 31. The first imaginary straight line L1 is a line passing through a portion of the first upstream surface 313 of the first guide structure 31 located most upstream in the planar first direction E1 and a portion of the first upstream surface 313 of the first guide structure 31 located most downstream in the planar first direction E1. When the entire first guide structure 31 extends linearly from the connection portion 33 toward the first smooth portion 26A, the deviation distance is 0 mm.

[0065] The structure of the second guide structure 32 will now be described. As shown in Fig. 5A, the second guide structure 32 includes a second end portion 321 adjacent to the second smooth portion 26B. The second end portion 321 is a portion of the second guide structure 32 adjacent to the second smooth portion 26B and having a dimension K in the second planar direction E2.

[0066] The second end portion 321 extends toward the second smooth portion 26B in a direction inclined with respect to the first planar direction E1. The angle that the second end portion 321 forms with respect to the first planar direction E1 is also referred to as the second inclination angle and is denoted by the symbol φ2. The second inclination angle φ2 is less than 90°. Therefore, the second guide structure 32 can impart a velocity component toward the second smooth portion 26B to the fluid F that collides with the second guide structure 32. The second inclination angle φ2 may be the same as or different from the first inclination angle φ1. The numerical range of the second inclination angle φ2 can be the same as the numerical range of the first inclination angle φ1 described above.

[0067] 5A, the second guide structure 32 includes a second upstream surface 323 and a second downstream surface 324. The second upstream surface 323 is a side surface of the second guide structure 32 located on the upstream side in the planar first direction E1. The second downstream surface 324 is a side surface of the second guide structure 32 located on the downstream side in the planar first direction E1. The second inclination angle φ2 is the angle formed by the intersection line between the second upstream surface 323 of the second end portion 321 and a base surface 21B (described later) with respect to the planar first direction E1.

[0068] Similar to the first guide structure 31, the second guide structure 32 may extend linearly toward the second smooth portion 26B. For example, an end of the second upstream surface 323 of the second guide structure 32 may extend toward the second smooth portion 26B at a second inclination angle φ2 in a plan view. This allows the fluid F that collides with the second guide structure 32 to be efficiently guided toward the second smooth portion 26B. The symbol K2 represents the dimension in the second planar direction E2 of the portion of the second guide structure 32 that extends linearly toward the second smooth portion 26B. K2 / S21, which is the ratio of the dimension K2 to the width S21, is, for example, 0.20 or more, or may be 0.30 or more, or may be 0.40 or more.

[0069] Similar to the first guide structure 31, the second guide structure 32 may extend linearly from the connecting portion 33 toward the second smooth portion 26B in its entirety. For example, the second guide structure 32 may have a deviation distance of 0.1 mm or less. The deviation distance is the maximum distance in the first planar direction E1 between the second imaginary straight line L2 and the second guide structure 32. The second imaginary straight line L2 is a straight line passing through a portion of the second upstream surface 323 of the second guide structure 32 located most upstream in the first planar direction E1 and a portion of the second upstream surface 323 of the second guide structure 32 located most downstream in the first planar direction E1. When the second guide structure 32 extends linearly from the connecting portion 33 toward the second smooth portion 26B in its entirety, the deviation distance is 0 mm.

[0070] The connection portion 33 is located between the first guide structure 31 and the second guide structure 32 in the planar second direction E2. The position of the connection portion 33 in the planar second direction E2 is determined by the dimension K1 of the first guide structure 31 and the dimension K2 of the second guide structure 32. For example, as shown in FIG. 5A , when the connection portion 33 is located approximately in the center of the friction portion 25 in the planar second direction E2, K1 / S21 and K2 / S21 are, for example, 0.40 or more and may be 0.45 or more. When the connection portion 33 is located approximately in the center of the friction portion 25 in the planar second direction E2, K1 / S21 and K2 / S21 are, for example, 0.60 or less and may be 0.55 or less.

[0071] 5B is a plan view showing a modified example of the structure 20. The connection portion 33 may be located away from the center of the friction portion 25 in the second planar direction E2. For example, the dimension K1 of the first guiding structure 31 may be smaller than the dimension K2 of the second guiding structure 32. For example, K1 / S21 may be 0.40 or less, and K2 / S21 may be 0.60 or more. For example, K1 / S21 may be 0.30 or less, and K2 / S21 may be 0.70 or more.

[0072] Next, the cross-sectional structure of the disturbance structure 30 will be described. Fig. 6A is a cross-sectional view showing the structure 20 of Fig. 4 as viewed from the VI-VI direction. The structure 20 may include a first surface 21 and a second surface 22. The second surface 22 is a surface located on the opposite side to the first surface 21 in the thickness direction of the structure 20. The second surface 22 may be a flat surface.

[0073] The first surface 21 may include a base surface 21B. For example, the structure 20 may include a base body 40 that includes the base surface 21B. The base surface 21B is the region of the first surface 21 that has the largest occupancy. The base surface 21B is distinguished from other regions of the first surface 21 based on the distance from the second surface 22 in the thickness direction of the structure 20. The occupancy rate of the base surface 21B in the first surface 21 is, for example, 50% or more, or may be 60% or more, or may be 70% or more.

[0074] 6A, the first guiding structure 31 of the disturbing structure 30 may protrude from the base surface 21B in the thickness direction of the structure 20. Such a disturbing structure 30 is also referred to as a convex portion. Although not shown, the second guiding structure 32 and the connecting portion 33 of the disturbing structure 30 may also be convex portions.

[0075] The convex portion of the first guide structure 31 has a first height H1 from the base surface 21B. The first height H1 is, for example, 1.0 mm or less, and may be 600 μm or less, 400 μm or less, 300 μm or less, or 200 μm or less. By reducing the first height H1, the frictional resistance that the fluid F experiences from the structure 20 can be reduced. The first height H1 is, for example, 20 μm or more, and may be 50 μm or more, or 100 μm or more.

[0076] In FIG. 6A, the symbol W1 represents the dimension of the first guiding structure 31 in the planar first direction E1. The dimension W1 is measured at a position where the first guiding structure 31 contacts the base surface 21B. The dimension W1 may be determined in relation to the first height H1. W1 / H1, which is the ratio of the dimension W1 to the first height H1, is, for example, 0.3 or more, or may be 0.5 or more, or may be 0.7 or more. W1 / H1 is, for example, 3.0 or less, or may be 2.0 or less, or may be 1.5 or less. 5A, symbol W12 represents the dimension of the first guiding structure 31 in a direction perpendicular to the direction in which the first guiding structure 31 extends. Like symbol W1, dimension W12 is measured at a position where the first guiding structure 31 contacts the base surface 21B. The ratio W12 / H1 of dimension W12 to first height H1 can be within the above-described range of values ​​for W1 / H1.

[0077] In FIG. 6A, the symbol G11 represents the distance between two first guiding structures 31 arranged in the first planar direction E1. The distance G11 may be determined in relation to the first height H1. The ratio G11 / H1 of the distance G11 to the first height H1 is, for example, 1.0 or more, or may be 3.0 or more, or 5.0 or more. As a result, as shown in FIG. 6A, the fluid F1 deflected upward by colliding with a convex portion can collide again with a downstream convex portion. This allows the fluid F flowing along the friction portion 25 to repeatedly collide with the first guiding structures 31. G11 / H1 is, for example, 12.0 or less, or may be 10.0 or less, or 9.0 or less. This sufficiently increases the frequency with which the fluid F collides with the first guiding structures 31. These factors promote mixing of the fluid F in the boundary layer between the fluid F and the surface of the object 10. Therefore, fluid separation can be suppressed.

[0078] The second guiding structure 32 and the connecting portion 33 may be configured similarly to the first guiding structure 31 . For example, the convex portion of the second guide structure 32 may have a second height H2. The second height H2 may be the same as or different from the first height H1. The numerical range of the second height H2 may be the same as the numerical range of the first height H1. For example, the second guide structure 32 may have a dimension W2 in the first planar direction E1. The dimension W2 may be determined in relation to the second height H2. The numerical range of W2 / H2, which is the ratio of the dimension W2 to the second height H2, can be the same as the numerical range of W1 / H1 described above. For example, the interval G21 between two second guide structures 32 arranged in the first planar direction E1 may be determined in relation to the second height H2. The numerical range of G21 / H2, which is the ratio of the interval G21 to the second height H2, can be the numerical range of G11 / H1 described above. For example, the dimension W22 of the second guide structure 32 in a direction perpendicular to the extension direction of the second guide structure 32 may be determined in relation to the second height H2. The numerical range of W22 / H2, which is the ratio of the dimension W22 to the second height H2, can be the numerical range of W12 / H1 described above.

[0079] FIG. 6A illustrates an example in which the fluid F1 that has passed through the first guide structures 31 in the friction section 25 flows along the first planar direction E1. Although not illustrated, it is conceivable that a portion of the fluid F1 that has passed through the first guide structures 31 flows in a direction perpendicular to the direction in which the first guide structures 31 extend. In FIG. 5A, the symbol G12 represents the distance between two first guide structures 31 in a direction perpendicular to the direction in which the first guide structures 31 extend. Similar to the distance G11, the distance G12 may be determined in relation to the first height H1. The ratio G12 / H1 of the distance G12 to the first height H1 is, for example, 1.0 or greater, 3.0 or greater, or even 5.0 or greater. This allows the fluid F1 deflected upward by colliding with a convex portion to collide again with a convex portion downstream. This allows the fluid F to repeatedly collide with the first guide structures 31 in the friction section 25. G12 / H1 is, for example, 12.0 or less, or may be 10.0 or less, or may be 9.0 or less. This sufficiently increases the frequency with which the fluid F collides with the first guiding structure 31. These factors promote mixing of the fluid F in the boundary layer between the fluid F and the surface of the object 10. Therefore, separation of the fluid can be suppressed.

[0080] 5A, the symbol G22 represents the distance between two second guide structures 32 in a direction perpendicular to the direction in which the second guide structures 32 extend. Similar to the distance G21, the distance G22 may be determined in relation to the second height H2. The numerical range of G22 / H2, which is the ratio of the distance G22 to the second height H2, can be the same as the numerical range of G12 / H1 described above.

[0081] As described above, it is preferable that the fluid F1 deflected upward by colliding with the upstream first guide structure 31 collide again with the downstream first guide structure 31. The base surface 21B located between two first guide structures 31 aligned in the planar first direction E1 is also referred to as a valley region. In order for the fluid F1 to collide again with the downstream first guide structure 31, it is preferable that no large protrusions are arranged in the valley region 21B1. This configuration prevents the valley region 21B1 from disrupting the flow of the fluid F1. The above-mentioned interval G11 corresponds to the dimension of the valley region 21B1 in the planar first direction E1.

[0082] 6B is a cross-sectional view showing a modified example of the structure 20. Small protrusions 34s may be arranged on the base surface 21B located between two first guide structures 31 aligned in the first planar direction E1. If the height of the small protrusions 34s is small, the flow of the fluid F1 is hardly disturbed by the small protrusions 34s. Therefore, the fluid F1 that collides with the first guide structure 31 on the upstream side can collide again with the first guide structure 31 on the downstream side.

[0083] 6B, the symbol Hd represents the distance from the top of the convex portion of the first guiding structure 31 to the top of the small protrusion 34s in the normal direction of the base surface 21B. A preferable range of the distance Hd may be determined relative to the first height H1 of the convex portion of the first guiding structure 31. Hd / H1, which is the ratio of the distance Hd to the first height H1, is, for example, 0.50 or more, 0.60 or more, 0.70 or more, 0.80 or more, or 0.90 or more. Hd / H1, which is the ratio of the distance Hd to the first height H1, is, for example, 1.00 or less, 0.99 or less, or 0.98 or less.

[0084] The layer structure of the structure 20 will be described. The base body 40 constituting the base surface 21B may include multiple layers. For example, the base body 40 may include a first substrate 41 constituting the base surface 21B. The first substrate 41 may be a plastic film. The plastic film may be a stretched plastic film or an unstretched plastic film. The material of the first substrate 41 is, for example, polyvinyl chloride, polypropylene, polyethylene, polyester, etc.

[0085] The base body 40 may include an adhesive layer 42 that forms the second surface 22. The adhesive layer 42 may have adhesive properties relative to the surface of the object 10. The adhesive layer 42 can be used to attach the structure 20 to the surface of the object 10.

[0086] The base body 40 may include a printed layer 44 located between the first substrate 41 and the adhesive layer 42. The printed layer 44 is a layer for displaying characters, images, etc. on the structure 20. The base body 40 may include a second substrate 45 that supports the printed layer 44. The base body 40 may include an adhesive layer 46 located between the printed layer 44 and the first substrate 41. The adhesive layer 46 can bond the first substrate 41 and the second substrate 45 on which the printed layer 44 is provided.

[0087] The thickness of the base body 40 is, for example, 300 μm or less, and may be 250 μm or less, 200 μm or less, or 150 μm or less. This allows the base body 40 to deform along the shape of the surface of the object 10. The thickness of the base body 40 is, for example, 50 μm or more, and may be 70 μm or more, or 100 μm or more.

[0088] The method for forming the disturbance structure 30 is not particularly limited. For example, the disturbance structure 30 may be formed by forming a resin layer on the base surface 21B of the base body 40 and then processing the resin layer using a mold such as a shaping roll. If the disturbance structure 30 is a convex portion, the convex portion may be formed by selectively applying a material constituting the convex portion onto the base surface 21B by an inkjet method or the like. After performing a process for determining the shape of the disturbance structure 30, such as a convex portion, the disturbance structure 30 may be subjected to a curing treatment. For example, if the material of the disturbance structure 30 is UV-curable, the disturbance structure 30 may be irradiated with UV light.

[0089] Although not shown, the disturbing structure 30 may be configured integrally with the first substrate 41. "Integral" means that there is no interface between the disturbing structure 30 and the first substrate 41. For example, first, a first substrate 41 having a thickness greater than the first height H1 may be prepared, and then the first substrate 41 may be processed using a shaping roll or the like. This results in a disturbing structure 30 that is integral with the first substrate 41. For example, first, a mold is prepared. Then, a fluid raw material is poured into the mold. The raw material may contain a resin. The raw material may contain a resin and a solvent. Next, the raw material is solidified in the mold. For example, the raw material is heated to evaporate the solvent. As a result, the structure 20 is formed inside the mold. Thereafter, the structure 20 is removed from the mold. As a result, the disturbance structure 30 integrated with the first substrate 41 is obtained.

[0090] 6B is a cross-sectional view showing an example of structure 20 in a state before being attached to object 10. Structure 20 may include separator 43 in contact with adhesive layer 42. Structure 20 may be distributed in a state in which separator 43 is included. In the process of attaching structure 20 to object 10, separator 43 is removed, and then structure 20 is attached to object 10.

[0091] The positions, shapes, etc. of the components on the first surface 21 of the structure 20 are measured using a laser displacement sensor. Based on the measurement results, the above-mentioned length S1, width S21, width S22, first inclination angle φ1, second inclination angle φ2, first height H1, second height H2, interval G11, interval G21, etc. are calculated.

[0092] Next, the smooth portion 26 will be described. The smooth portion 26 may include the above-mentioned base surface 21B. The occupancy rate of the base surface 21B in the friction portion 25 is referred to as a first base ratio R1. The occupancy rate of the base surface 21B in the smooth portion 26 is referred to as a second base ratio R2. The second base ratio R2 is higher than the first base ratio R1. The second base ratio R2 is, for example, 70% or more, may be 80% or more, 90% or more, 95% or more, 99% or more, or may be 100%.

[0093] FIG. 7 is a plan view showing an example of vortices generated in the structure 20. The friction portion 25 and the smooth portion 26 extend in the first planar direction E1. The friction portion 25 includes a first guide structure 31 extending toward the first smooth portion 26 at a first inclination angle φ1. This allows a fluid vortex F2 to be generated effectively along a boundary line 27 between the friction portion 25 and the first smooth portion 26. For example, even if the first height of the convex portion of the first guide structure 31 is small, the energy of the vortex F2 can be sufficiently increased. The friction portion 25 also includes a second guide structure 32 extending toward the second smooth portion 26 at a second inclination angle φ2. This allows a fluid vortex F2 to be generated effectively along the boundary line 27 between the friction portion 25 and the second smooth portion 26. For example, even if the first height of the convex portion of the second guide structure 32 is small, the energy of the vortex F2 can be sufficiently increased. This reduces the frictional resistance that the fluid F experiences from the structure 20 while suppressing separation of the fluid F.

[0094] 7, the energy of the vortex F2 may increase toward the downstream side, which can further suppress separation of the fluid F.

[0095] Fig. 8 is a diagram showing an example of the state of fluid F flowing along the surface of object 10 having structure 20. In the example shown in Fig. 8, structure 20 is attached to the inclined portion of rear surface 12. Therefore, separation of fluid F from the inclined portion of rear surface 12 can be suppressed.

[0096] 9 is a diagram showing an example of the state of fluid F flowing along the surface of object 100 in a comparative embodiment. Object 100 in the comparative embodiment does not include structure 20. For this reason, it is thought that fluid F separates from object 100 near the upstream end of the inclined portion of rear surface 12, creating a dead water region 19 between fluid F and object 100. As a result, the pressure resistance that object 100 experiences from fluid F increases.

[0097] In contrast, in the present embodiment, the structure 20 can suppress separation of the fluid F at the inclined portion of the rear surface 12. For example, compared to the comparative embodiment, the separation point 18, where separation of the fluid F from the object 10 occurs, can be positioned further downstream. This makes it possible to reduce the pressure resistance that the object 10 receives from the fluid F, compared to the comparative embodiment.

[0098] The first embodiment described above can be modified in various ways. Hereinafter, other embodiments will be described with reference to the drawings as necessary. In the following description and the drawings used in the following description, parts that can be configured similarly to the first embodiment described above will be designated by the same reference numerals as those used for the corresponding parts in the first embodiment described above. Duplicate descriptions will be omitted. Furthermore, if it is clear that the effects obtained in the first embodiment described above can also be obtained in other embodiments, the descriptions may be omitted.

[0099] (First Modification) Fig. 10 is a cross-sectional view showing the structure 20 in the first modified example. As shown in Fig. 10, the disturbance structure 30 may be recessed with respect to the base surface 21B in the thickness direction of the structure 20. Such a disturbance structure 30 is also referred to as a recess. By using a recess, an increase in frictional resistance caused by the structure 20 can be suppressed. Furthermore, damage to the disturbance structure 30 can be suppressed compared to when a protrusion is used.

[0100] The recess has a second depth H2 from the base surface 21B. The second depth H2 is, for example, 400 μm or less, and may be 300 μm or less, or 200 μm or less. By reducing the second depth H2, the frictional resistance that the fluid F experiences from the structure 20 can be reduced. The second depth H2 is, for example, 20 μm or more, and may be 50 μm or more, or 100 μm or more.

[0101] (Second Modification) 11A is a plan view showing a disturbance structure 30 in a second modified example. As shown in FIG. 11A, a connection portion 33 connecting the first guiding structure 31 and the second guiding structure 32 may extend in the second direction D2. The connection portion 33 has a dimension K3 in the planar second direction E2. The ratio K3 / S21 of the dimension K3 to the width S21 described above is, for example, 0.20 or more, or may be 0.30 or more, or may be 0.40 or more.

[0102] The first downstream surface 314 of the first guide structure 31 may extend parallel to the first upstream surface 313. The second downstream surface 324 of the second guide structure 32 may extend parallel to the second upstream surface 323.

[0103] The connection portion 33 includes a third upstream surface 333 and a third downstream surface 334. The third upstream surface 333 is a side surface of the connection portion 33 located on the upstream side in the planar first direction E1. The third downstream surface 334 is a side surface of the connection portion 33 located on the downstream side in the planar first direction E1. The third downstream surface 334 of the connection portion 33 may extend parallel to the third upstream surface 333. For example, the third upstream surface 333 and the third downstream surface 334 may extend in the second direction D2.

[0104] (Third Modification) Fig. 11B is a plan view showing a disturbing structure 30 in a third modified example. The connecting portion 33 in this modified example also extends in the second direction D2, similar to the example shown in Fig. 11A.

[0105] The first guide structure 31 may include a portion whose width decreases toward the first end portion 311. The second guide structure 32 may similarly include a portion where the distance between the second upstream surface 323 and the second downstream surface 324 decreases toward the second end portion 321. For example, the first downstream surface 314 of the first guide structure 31, the second downstream surface 324 of the second guide structure 32, and the third downstream surface 334 of the connecting portion 33 may all extend in the second direction D2. For example, the disturbance structure 30 may be trapezoidal in a plan view.

[0106] (Fourth Modification) Fig. 12 is a plan view showing a disturbance structure 30 in a fourth modified example. As shown in Fig. 12, the first guide structure 31 may include a portion whose width increases toward the first end portion 311. For example, the first guide structure 31 may include a portion where the distance between the first upstream surface 313 and the first downstream surface 314 increases toward the first end portion 311. Similarly, the second guide structure 32 may include a portion where the distance between the second upstream surface 323 and the second downstream surface 324 increases toward the second end portion 321.

[0107] (Fifth Modification) Fig. 13 is a plan view showing a disturbance structure 30 in a fifth modified example. As shown in Fig. 13, the first guide structure 31 may include a portion whose width decreases as it approaches the first end portion 311. For example, the first guide structure 31 may include a portion where the distance between the first upstream surface 313 and the first downstream surface 314 decreases as it approaches the first end portion 311. Similarly, the second guide structure 32 may include a portion where the distance between the second upstream surface 323 and the second downstream surface 324 decreases as it approaches the second end portion 321.

[0108] (Sixth Modification) FIG. 14A is a plan view showing a disturbance structure 30 according to a sixth modified example. As shown in FIG. 14A, the disturbance structure 30 may have a curved shape in a plan view. For example, the disturbance structure 30 may have a curved shape that is convex toward the upstream side in a plan view. In this case, the first inclination angle φ1 of the first guiding structure 31 is calculated as the average value of the inclination angles with respect to the first direction E1 at each position of the first end portion 311 having the dimension K. Specifically, the inclination angle is measured at each position of the first end portion 311 divided into 10 equal parts in the first direction E1. Similarly, the second inclination angle φ2 of the second guiding structure 32 is calculated as the average value of the inclination angles with respect to the first direction E1 at each position of the second end portion 321 having the dimension K.

[0109] (Seventh Modification) Fig. 14B is a plan view showing a disturbance structure 30 in a seventh modified example. As in the example shown in Fig. 14A, the disturbance structure 30 may have a curved shape in a plan view. Furthermore, as in the example shown in Fig. 13, the first guide structure 31 may include a portion where the distance between the first upstream surface 313 and the first downstream surface 314 decreases as the distance approaches the first end portion 311. Similarly, the second guide structure 32 may include a portion where the distance between the second upstream surface 323 and the second downstream surface 324 decreases as the distance approaches the second end portion 321.

[0110] (Eighth Modification) Fig. 15A is a plan view showing a disturbing structure 30 in an eighth modified example. Similar to the example shown in Fig. 14A and Fig. 14B, the disturbing structure 30 in this modified example also has a curved shape that is convex toward the upstream side in plan view.

[0111] The first downstream surface 314 of the first guiding structure 31, the second downstream surface 324 of the second guiding structure 32, and the third downstream surface 334 of the connecting portion 33 may all extend in the second direction D2. For example, the disturbing structure 30 may be semicircular in a plan view.

[0112] (Ninth Variation) Fig. 15B is a plan view showing the disturbing structure 30 in the ninth modified example. The disturbing structure 30 in this modified example also has a curved shape that is convex toward the upstream side in plan view, similar to the example shown in Figs. 14A and 14B.

[0113] The disturbance structure 30 may have a curved shape that is convex toward the downstream side in a plan view. The first downstream surface 314 of the first guiding structure 31, the second downstream surface 324 of the second guiding structure 32, and the third downstream surface 334 of the connecting portion 33 may be continuous to realize the curved shape that is convex toward the downstream side.

[0114] (Tenth Modification) Fig. 16 is a plan view showing a disturbance structure 30 in a tenth modified example. As shown in Fig. 16, the first guide structure 31 and the second guide structure 32 do not have to be connected. That is, the disturbance structure 30 may include a gap 34 located between the first guide structure 31 and the second guide structure 32 in the second planar direction E2. Reference numeral 312 denotes an end portion (also referred to as a third end portion) of the first guide structure 31 facing the second guide structure 32 in the second planar direction E2. Reference numeral 322 denotes an end portion (also referred to as a fourth end portion) of the second guide structure 32 facing the first guide structure 31 in the second planar direction E2.

[0115] When the dimension U of the gap 34 in the second planar direction E2 is small, the effect of the gap 34 on the fluid F is negligible. When the dimension U is small, the area including the gap 34 is interpreted as part of the friction portion 25 including the first guide structure 31 and the second guide structure 32, rather than as part of the smooth portion 26. The dimension U may be, for example, 5.0 mm or less, 3.0 mm or less, 1.0 mm or less, 0.5 mm or less, or 0.1 mm or less. The dimension U may be determined in relation to the width S22 of the smooth portion 26. The ratio of the dimension U to the width S22, U / S22, is, for example, 1 / 5 or less, 1 / 10 or less, or 1 / 20 or less.

[0116] (Eleventh Modification) FIG. 17 is a plan view showing a structure 20 in an eleventh modified example. As shown in FIG. 17, the structure 20 includes a first guide structure 31, but may not include a second guide structure 32. For example, a first end portion 311 of the first guide structure 31 extending at a first inclination angle φ1 with respect to the second planar direction E2 may be in contact with the first smooth portion 26, and a third end portion 312 of the first guide structure 31 may be in contact with the second smooth portion 26. In this modified example, too, the generation of vortices at the boundary between the friction portion 25 and the first smooth portion 26 is promoted. This reduces the pressure resistance that the object 10 experiences from the fluid F.

[0117] (12th Modification) Fig. 18 is a plan view showing a modified example of the object 10. As shown in Fig. 18, the structure 20 may be attached to the front surface 11 of the object 10. This makes it possible to prevent separation of the fluid F in front of the object 10.

[0118] (13th Modification) In the above-described embodiment, an example has been described in which the structure 20 is attached to the object 10. However, the relationship between the structure 20 and the object 10 is not particularly limited. For example, as shown in FIG. 19 , the structure 20 may be a component that is provided on the object 10 when the object 10 is in circulation. For example, the structure 20 may be a component that forms part of the object 10. For example, if the object 10 is a car, the structure 20 may be one component that forms the object 10, such as a door visor. In other words, one component that forms the object 10 may have the features of the structure 20, such as the friction portion 25 and the smooth portion 26. In this case, the structure 20 may be a molded product produced by, for example, injection molding a resin.

[0119] (Other variations) In the above-described embodiment, an example has been shown in which the object 10 equipped with the structure 20 is a mobile object that can move itself. However, the object 10 is not particularly limited as long as the object 10 is in contact with the fluid F. For example, the object 10 may be a fixed object that does not move itself but controls the flow of the fluid F.

[0120] The moving body may be, for example, an automobile such as a passenger car, truck, or bus; a railway vehicle such as a train, bullet train, or locomotive; an aircraft such as an airplane, helicopter, or drone; or a bicycle. These moving bodies move through the atmosphere. The fluid in contact with the moving body is air. The object 10 having the structure 20 may be a part of these moving bodies. For example, the object 10 may be a component that constitutes the moving body, such as a housing.

[0121] The fixed object may be, for example, a pipe such as a duct or gas pipe; a windmill blade; or an air outlet or louver of an air conditioning device such as an air conditioner. These fixed objects control the flow of gas. The object 10 having the structure 20 may be a part of these fixed objects. For example, the object 10 may be a component that constitutes the surface of these fixed objects.

[0122] [Example] Next, the present disclosure will be described in more detail with reference to examples. However, the present disclosure is not limited to the following examples as long as it does not depart from the gist of the disclosure.

[0123] (Example A1) The effect of structure 20 was verified by a wind tunnel experiment in which an airflow was made to collide with object 10 to which structure 20 was attached. Specifically, an airflow was made to collide with object 10, with structure 20 attached to the upstream portions of top surface 13 and side surface 14 of a rectangular parallelepiped object. The dimensions of the object were 1250 mm in length in the direction of airflow, 260 mm in width, and 387 mm in height.

[0124] A method for producing the structure 20 will be described. First, a second film including a second substrate 45 containing polyvinyl chloride and an adhesive layer 42 was prepared. Avery Dennison general-purpose inkjet media MPI1105 was used as the second film. Next, a printed layer 44 including a design was formed on the second substrate 45 of the second film. Next, a first substrate 41 was laminated on the printed layer 44 via an adhesive layer 46. Avery Dennison wrapping film DOL1460 was used as the first film including the first substrate 41 and the adhesive layer 46. In this manner, a laminate constituting the base body 40 was produced.

[0125] Next, a UV-curable material was applied onto the base body 40 by an inkjet method. The material was then cured using UV light. As a result, a disturbance structure 30 including a first guide structure 31 and a second guide structure 32 each consisting of a convex portion, as shown in FIG. 4, was formed on the base body 40. In this way, a structure 20 was produced that included a friction portion 25 including the first guide structure 31 and the second guide structure 32, and a smooth portion 26.

[0126] The structure 20 is configured as follows. Length of friction part 25 S1: 200mm Length of smooth section 26: 200mm Width of friction part 25 S21: 7mm Width of smooth part 26 S22: 7mm First inclination angle φ1 of the first guiding structure 31: 30° First height H1 of the convex portion of the first guiding structure 31: 0.16 mm Width W12 of the convex portion of the first guiding structure 31: 0.14 mm Distance G12 between the two first guide structures 31: 0.26 mm Second inclination angle φ2 of the second guide structure 32: 30° Second height H2 of the convex portion of the second guiding structure 32: 0.16 mm Width W22 of the convex portion of the second guiding structure 32: 0.14 mm Distance G22 between two second guide structures 32: 0.26mm

[0127] The air resistance coefficient was measured when the airflow speed was set to 30 m / s. The air resistance coefficient is also called the Cd value. The air resistance coefficient was calculated based on the drag force acting on the object 10 due to the airflow. The drag force was measured using a load cell via a wire fixed to the object 10. The results are shown in FIG. 20.

[0128] (Example A2) The air resistance coefficient was measured in the same manner as in Example A1, except that the first inclination angle φ1 and the interval G12 of the first guiding structure 31 and the second inclination angle φ2 and the interval G22 of the second guiding structure 32 were changed as follows. The results are shown in Figure 20. First inclination angle φ1 of the first guiding structure 31: 45° Distance G12 between the two first guide structures 31: 0.43 mm Second inclination angle φ2 of the second guide structure 32: 45° Distance G22 between two second guide structures 32: 0.43mm

[0129] (Example A3) The air resistance coefficient was measured in the same manner as in Example A1, except that the first inclination angle φ1 and the interval G12 of the first guiding structure 31 and the second inclination angle φ2 and the interval G22 of the second guiding structure 32 were changed as follows. The results are shown in Figure 20. First inclination angle φ1 of the first guiding structure 31: 60° Distance G12 between the two first guide structures 31: 0.55 mm Second inclination angle φ2 of the second guide structure 32: 60° Distance G22 between two second guide structures 32: 0.55mm

[0130] (Example A4) The air resistance coefficient was measured in the same manner as in Example A1, except that the first height H1 of the first guiding structure 31 and the second height H2 of the second guiding structure 32 were changed as follows. The results are shown in Figure 20. First height H1 of the convex portion of the first guiding structure 31: 0.13 mm Second height H2 of the convex portion of the second guiding structure 32: 0.13 mm

[0131] (Example A5) The air resistance coefficient was measured in the same manner as in Example A1, except that the spacing G12 of the first guiding structure 31 and the spacing G22 of the second guiding structure 32 were changed as follows. The results are shown in Figure 20. Distance G12 between the two first guide structures 31: 0.66 mm Distance G22 between two second guide structures 32: 0.66mm

[0132] (Comparative Example A1) The air resistance coefficient was measured in the same manner as in Example A1, except that the structure 20 was not attached to the object 10. The results are shown in FIG.

[0133] (Comparative example A2) The air resistance coefficient was measured in the same manner as in Example A1, except that the first inclination angle φ1 and the interval G12 of the first guiding structure 31 and the second inclination angle φ2 and the interval G22 of the second guiding structure 32 were changed as follows. The results are shown in Figure 20. First inclination angle φ1 of the first guiding structure 31: 90° Distance G12 between the two first guide structures 31: 0.66 mm Second inclination angle φ2 of the second guide structure 32: 90° Distance G22 between two second guide structures 32: 0.66mm

[0134] As can be seen from the comparison between Examples A1 to A5 and Comparative Example A1, by attaching structure 20 to object 10, the air resistance coefficient could be reduced.

[0135] As can be seen from a comparison between Examples A1 to A5 and Comparative Example A2, the air resistance coefficient could be reduced by inclining the first guiding structure 31 and the second guiding structure 32 at an angle of less than 90° with respect to the first planar direction E1.

[0136] (Example A11) In the same manner as in Example A1, a structure 20 was produced. The structure 20 had the following configuration. Length of friction part 25 S1: 105mm Width of friction part 25 S21: 7mm Width of smooth part 26 S22: 7mm First inclination angle φ1 of the first guiding structure 31: 30° First height H1 of the convex portion of the first guiding structure 31: 0.15 mm Width W12 of the convex portion of the first guiding structure 31: 0.14 mm Distance G12 between the two first guide structures 31: 1.40 mm Second inclination angle φ2 of the second guide structure 32: 30° Second height H2 of the convex portion of the second guiding structure 32: 0.15 mm Width W22 of the convex portion of the second guiding structure 32: 0.14 mm Distance G22 between two second guide structures 32: 1.40mm

[0137] Next, as in Example A1, an airflow was made to collide with the rectangular parallelepiped object 10, with the structure 20 attached to the upstream portions of the top surface 13 and side surface 14 of the object. The measurement results of the air resistance coefficient are shown in Figs. 21 and 22.

[0138] (Examples A12 to A13) The air resistance coefficient was measured in the same manner as in Example A11, except that the length S1 of the friction portion 25 was changed as shown in Fig. 21. The measurement results are shown in Figs.

[0139] (Examples A14 to A16) The air resistance coefficient was measured in the same manner as in Example A12, except that the width S21 of the friction portion 25 was changed as shown in Fig. 21. The measurement results are shown in Figs.

[0140] (Comparative Example A11) The air resistance coefficient was measured in the same manner as in Example A11, except that the structure 20 was not attached to the object 10. The results are shown in Figs.

[0141] As can be seen from FIG. 22, when the length S1 of the friction portion 25 was within the range of 105 mm to 420 mm, the air resistance coefficient was almost constant regardless of the length S1.

[0142] As can be seen from Fig. 23, in areas where the wind speed is high, the air resistance coefficient tends to increase as the width S21 of the friction area increases. It is thought that the increase in the width S21 of the friction area increases the friction resistance.

[0143] (Examples A21 to A26) The air resistance coefficient was measured in the same manner as in Example A12, except that the height H1 of the convex portions, the width W12 of the convex portions, and the interval G12 of the first guiding structure 31 were changed as shown in Fig. 24. Although not shown in Fig. 24, the second height H2 of the convex portions, the width W22 of the convex portions, and the interval G22 of the second guiding structure 32 are the same as the height H1 of the convex portions, the width W12 of the convex portions, and the interval G12 of the first guiding structure 31. The measurement results are shown in Figs. 24 and 25.

[0144] (Examples A27 to A28) The air resistance coefficient was measured in the same manner as in Example A12, except that the height H1 of the convex portions, the width W12 of the convex portions, and the interval G12 of the first guiding structure 31 were changed as shown in Fig. 24. Although not shown in Fig. 24, the second height H2 of the convex portions, the width W22 of the convex portions, and the interval G22 of the second guiding structure 32 are the same as the height H1 of the convex portions, the width W12 of the convex portions, and the interval G12 of the first guiding structure 31. The measurement results are shown in Figs. 24 and 26.

[0145] As can be seen from a comparison between Comparative Example A11 and Example A21 in Fig. 25, a reduction in the air resistance coefficient was confirmed even when the height H1 of the convex portions was 20 μm. As can be seen from a comparison between Examples A22 to A26 in Fig. 25, the effect of reducing the air resistance coefficient became more apparent at lower speeds as the height H1 of the convex portions increased.

[0146] As can be seen from FIG. 26, when the ratio of the spacing G12 to the height H1 of the convex portions was within the range of 5 to 10, the air resistance coefficient was almost constant regardless of the ratio.

[0147] A second embodiment of the present disclosure will be described. Like the first embodiment, the second embodiment also relates to a structure that comes into contact with a fluid. In the description of the second embodiment, parts that can be configured in the same manner as the first embodiment or its modified examples described above will be designated by the same reference numerals as those used for the corresponding parts in the first embodiment or its modified examples described above. Duplicate descriptions will be omitted. Furthermore, if it is clear that the effects obtained in the first embodiment or its modified examples described above can also be obtained in the second embodiment, the description may be omitted.

[0148] Fluid separation is likely to occur in curved portions of an object's surface. The second embodiment has been made in consideration of this point. The second embodiment aims to provide a structure that suppresses fluid separation from occurring in curved portions of an object.

[0149] The second embodiment relates to the following [1] to

[20] . [1] A structure for reducing fluid resistance, a first surface including a curved surface and in contact with the fluid; a friction portion located at least on the curved surface and extending in a first surface direction that is a curvature direction of the curved surface; A structure comprising: a smooth portion located at least on the curved surface and adjacent to the friction portion in a second planar direction intersecting the first planar direction.

[0150] [2] In the structure described in [1], a boundary line between the friction portion and the smooth portion may extend parallel to the first surface direction.

[0151] [3] In the structure according to [1] or [2], the friction portion may have a length of 30 mm or more and 1000 mm or less in the first direction of the surface.

[0152] [4] In the structure according to any one of [1] to [3], the friction portion may have a width of 0.2 mm or more and 50 mm or less in a direction perpendicular to the first surface direction.

[0153] [5] In the structure according to any one of [1] to [4], the smooth portion may include a plurality of rectifying structures extending in the first direction of the surface.

[0154] [6] In the structure described in any one of [1] to [5], the friction portion may have a first arithmetic mean height and a first maximum height, and the smooth portion may have a second arithmetic mean height smaller than the first arithmetic mean height and a second maximum height smaller than the first maximum height.

[0155] [7] In the structure according to [6], a ratio of the first maximum height to the first arithmetic mean height may be 5 or more.

[0156] [8] In the structure according to any one of [1] to [5], the friction portion may include a plurality of disturbance structures arranged in the first direction of the surface, which disturb the flow of the fluid.

[0157] [9] A structure for reducing fluid resistance, a first surface including a curved surface and in contact with the fluid; a friction portion located at least on the curved surface and extending in a first surface direction that is a curvature direction of the curved surface, The friction portion includes a disturbance structure extending along a second direction intersecting the first direction.

[0158]

[10] In the structure described in [8] or [9], the first surface may include a base surface, and the disturbance structure may protrude from the base surface in the thickness direction of the structure.

[0159]

[11] In the structure described in

[10] , the disturbing structure may have a first height from the base surface, and the first height may be 20 μm or more and 1.0 mm or less.

[0160]

[12] In the structure described in

[11] , the ratio of the spacing between the plurality of disturbance structures aligned in the first direction of the surface to the first height may be 1.0 or more and 12.0 or less.

[0161]

[13] In the structure described in [8] or [9], the first surface may include a base surface, and the disturbance structure may be recessed relative to the base surface in the thickness direction of the structure.

[0162]

[14] In the structure described in [8] and

[10] , the friction portion may include the base surface at a first base ratio, and the smooth portion may include the base surface at a second base ratio higher than the first base ratio.

[0163]

[15] In the structure described in any one of [8] to

[14] , the first surface may include a first region including the curved surface and a second region aligned with the first region in the first direction of the surface and flatter than the first region, and the spacing between two of the disturbance structures aligned in the first direction of the surface in the first region may be larger than the spacing between two of the disturbance structures aligned in the first direction of the surface in the second region.

[0164]

[16] In the structure according to any one of [1] to

[15] , the curved surface may have a curved angle of 30° or more.

[0165]

[17] An object in contact with a fluid, A curved portion; An object comprising the structure according to any one of [1] to

[16] attached to the curved portion.

[0166]

[18] An object in contact with a fluid, a component including a curved portion; The part is an object made of the structure according to any one of [1] to

[16] .

[0167]

[19] The object described in

[17] or

[18] may be a moving object or part of a moving object.

[0168]

[20] The object described in

[17] or

[18] may control the flow of a fluid.

[0169] According to the second embodiment, it is possible to prevent separation of the fluid from occurring at the curved portion of the object.

[0170] The configuration of a structure 20 and an object 10 including the structure 20 according to the second embodiment will be described in detail below with reference to the drawings. Fig. 27 is a side view showing an example of the object 10. Fig. 28 is a plan view showing an example of the object 10. As shown in Figs. 27 and 28, the object 10 may be a moving object such as a bus.

[0171] The object 10 may include a front surface 11 and a rear surface 12. The front surface 11 is the surface of the object 10 located upstream in the flow direction of the fluid F. The fluid F collides with the front surface 11. The rear surface 12 is the surface of the object 10 located downstream in the flow direction of the fluid F. The rear surface 12 is located opposite the front surface 11 in the flow direction of the fluid F.

[0172] The flow direction of the fluid F is the relative movement direction of the fluid F with respect to the object 10. In the examples shown in FIGS. 27 and 28, a situation is assumed in which the object 10 moves forward. The flow direction of the fluid F is also referred to as the first direction and is represented by the symbol D1. The symbols D2 and D3 represent the second direction and the third direction, respectively. The second direction D2 and the third direction D3 are each perpendicular to the first direction D1. Furthermore, the second direction D2 and the third direction D3 are perpendicular to each other. In the examples shown in FIGS. 27 and 28, the second direction D2 is a direction perpendicular to the first direction D1 and along a horizontal plane, and the third direction D3 is a direction perpendicular to the first direction D1 and along a vertical plane.

[0173] The object 10 includes a side surface 14 extending from a front surface 11 to a rear surface 12. A fluid F flows downstream along the side surface 14. The side surface defining the top end of the object 10 is also referred to as an upper surface 13.

[0174] As shown in FIGS. 27 and 28, the object 10 includes a curved portion 15 located between the front surface 11 and the side surface 14. The curved portion 15 is a portion whose surface normal direction changes depending on the position. For example, at the boundary between the curved portion 15 and the front surface 11, the normal direction of the curved portion 15 is parallel to the first direction D1. For example, at the boundary between the curved portion 15 and the side surface 14, the normal direction of the curved portion 15 is parallel to the second direction D2. The angle corresponding to the amount of change in the normal direction of the curved portion 15 is also referred to as the curvature angle of the curved portion 15. In the example shown in FIGS. 27 and 28, the curvature angle of the curved portion 15 is 90°.

[0175] 27 and 28, the object 10 includes a structure 20 attached to the curved portion 15. The structure 20 is configured to generate vortices to promote mixing of the fluid. By attaching the structure 20 to the curved portion 15, separation of the fluid F at the curved portion 15 can be suppressed.

[0176] The structure 20 includes a first surface 21 that contacts the fluid F. The first surface 21 includes a curved region. The curved region of the first surface 21 is also referred to as a curved surface. The first surface 21 may include a flat region.

[0177] In this embodiment, the structure 20 has flexibility. Therefore, the structure 20 attached to the curved portion 15 of the object 10 deforms according to the shape of the curved portion 15. As a result, a curved surface is generated on the first surface 21 of the structure 20.

[0178] FIG. 29 is a perspective view showing an example of a structure 20 attached to an object 10. The structure 20 extends along a first surface direction E1. The first surface direction E1 is the curvature direction of the curved surface of the first surface 21. The curvature direction is a direction along the first surface 21, and is a direction in which the rate of change of the normal direction N of the first surface 21 is maximum. The rate of change of the normal direction N is the amount of change in the vector representing the normal direction N when moving a unit distance along the first surface 21.

[0179] For example, in Figure 29, line L2 extends in a direction along the first surface 21 and parallel to the third direction D3. The amount of change in the normal direction N before and after moving a unit distance along line L2 is zero. Line L1 is a line along the first surface 21 that extends in a direction perpendicular to line L2. If the amount of change in the normal direction N when moving a unit distance along line L1 is larger than the amount of change in the normal direction N when various other lines are used, the direction in which line L1 extends is defined as the surface first direction E1.

[0180] FIG. 30 is an enlarged view of the structure 20 of FIG. 3. As shown in FIG. 30, the structure 20 includes a friction portion 25 and a smooth portion 26 located on the first surface 21. The friction portion 25 and the smooth portion 26 extend in a first surface direction E1. The smooth portion 26 is adjacent to the friction portion 25 in a second surface direction E2. The second surface direction E2 is a direction along the first surface 21 and intersects with the first surface direction E1. The second surface direction E2 may be perpendicular to the first surface direction E1. As shown in FIG. 30, a plurality of friction portions 25 and smooth portions 26 may be arranged alternately along the second surface direction E2.

[0181] In FIG. 30, the dotted line labeled 27 indicates the boundary between the friction portion 25 and the smooth portion 26. The imaginary line indicating the boundary is also referred to as a boundary line. The boundary line 27 may extend parallel to the first surface direction E1. For example, the angle formed between the direction in which the boundary line 27 extends and the first surface direction E1 may be equal to or smaller than a first threshold value TH1. The first threshold value TH1 is, for example, 10°, but may also be 5° or 3°. By having the boundary line 27 extend parallel to the first surface direction E1, the vortex generated at the boundary can be made larger.

[0182] As shown in FIG. 30, the first surface 21 may include a first region P1 and a second region P2 aligned in a first surface direction E1. The first region P1 includes a curved surface 211. The second region P2 is a region that is flatter than the first region P1. For example, the second region P2 may have a radius of curvature that is larger than the radius of curvature of the first region P1. The second region P2 may also be a flat region. In this case, the second region P2 may be interpreted as a region having an infinite radius of curvature.

[0183] 30, the curved surface 211 may be curved so as to bulge outward. "Bulging outward" means that the curved surface 211 is curved so as to be convex in the direction from the object 10 toward the first surface 21.

[0184] The structure 20 has a curvature angle θ. The curvature angle θ is the angle formed by two normal lines N1 and N2 to the first surface 21 that pass through both ends of the structure 20 in the first surface direction E1. The curvature angle θ is, for example, 30° or more, and may be 45° or more, 60° or more, or 80° or more. The curvature angle θ is, for example, 170° or less, 140° or less, or 120° or less.

[0185] 31 is a plan view showing the structure 20 based on a coordinate system of a first planar direction E1 and a second planar direction E2. The friction portion 25 is configured to disturb the flow of the fluid F. For example, the resistance experienced by the fluid F when it flows along the friction portion 25 is greater than the resistance experienced by the fluid F when it flows along the smooth portion 26. As a result, a flow deviating from the first direction D1 can be generated at the boundary between the friction portion 25 and the smooth portion 26. For example, a vortex can be generated in the fluid F at the boundary between the friction portion 25 and the smooth portion 26.

[0186] 31, the friction portion 25 may include a plurality of disturbance structures 30 that disturb the flow of the fluid F. The plurality of disturbance structures 30 may be aligned in a first planar direction E1. As shown in FIG. 31, the disturbance structures 30 may extend along a second planar direction E2 that intersects with the first planar direction E1. In this case, the boundary line 27 may be defined as a line passing through the ends of the plurality of disturbance structures 30.

[0187] In FIG. 31 , symbol S1 represents the dimension of the friction portion 25 in the first planar direction E1. The dimension S1 is also referred to as the length S1. The length S1 may be set so that a sufficient number of disturbance structures 30 are aligned in the first planar direction E1. The length S1 may be, for example, 5 mm or more, 10 mm or more, 25 mm or more, 30 mm or more, 50 mm or more, or 100 mm or more. This allows the fluid F flowing along the friction portion 25 to be repeatedly disturbed by the multiple disturbance structures 30. This promotes mixing of the fluid in the boundary layer between the fluid F and the surface of the object 10. This prevents fluid separation.

[0188] On the other hand, if the length S1 becomes too large, the frictional resistance that the fluid F receives from the structure 20 increases, hindering the flow of the fluid F. In consideration of this point, the length S1 is, for example, 1000 mm or less, or may be 500 mm or less, or may be 300 mm or less.

[0189] When the friction portion 25 includes a disturbance structure 30, the length S1 of the friction portion 25 is determined based on the disturbance structure 30 located most upstream and the disturbance structure 30 located most downstream in the flow direction of the fluid F, as shown in Figure 31.

[0190] The length of the smooth portion 26 in the first surface direction E1 may be the same as or different from the length S1 of the friction portion 25. The numerical range of the length of the smooth portion 26 may be the same as or different from the above-mentioned numerical range of the length S1.

[0191] 31, the symbol S21 represents the dimension of the friction portion 25 in the second planar direction E2. The dimension S21 is also referred to as the width S21. The width S21 may be set so that the friction portion 25 can sufficiently disrupt the flow of the fluid F. The width S21 is, for example, 0.2 mm or more, or may be 1.0 mm or more, or 5.0 mm or more.

[0192] On the other hand, if the width S21 becomes too large, the ratio of the size of the vortex generated at the boundary between the friction portion 25 and the smooth portion 26 to the width S21 becomes small. As a result, the ratio of the fluid F that is less affected by the vortex increases. In consideration of this point, the width S21 is, for example, 50 mm or less, and may be 30 mm or less, or 20 mm or less.

[0193] The width S22 of the smooth portion 26 in the second surface direction E2 may be the same as or different from the width S21 of the friction portion 25. The numerical range of the width S22 of the smooth portion 26 may be the same as or different from the above-mentioned numerical range of the width S21 of the friction portion 25.

[0194] Fig. 32A is a cross-sectional view showing the structure 20 of Fig. 31 as viewed from the XXXII-XXXII direction. The structure 20 may include a first surface 21 and a second surface 22. The second surface 22 is a surface located on the opposite side to the first surface 21 in the thickness direction of the structure 20. The second surface 22 may be a flat surface.

[0195] The first surface 21 may include a base surface 21B. For example, the structure 20 may include a base body 40 that includes the base surface 21B. The base surface 21B is the region of the first surface 21 that has the largest occupancy. The base surface 21B is distinguished from other regions of the first surface 21 based on the distance from the second surface 22 in the thickness direction of the structure 20. The occupancy rate of the base surface 21B in the first surface 21 is, for example, 50% or more, or may be 60% or more, or may be 70% or more.

[0196] 32A, the disturbance structures 30 may protrude from the base surface 21B in the thickness direction of the structure 20. Such disturbance structures 30 are also referred to as protrusions 301. The protrusions 301 may have a trapezoidal cross-sectional shape.

[0197] The protrusion 301 has a first height H1 from the base surface 21B. The first height H1 is, for example, 1.0 mm or less, and may be 600 μm or less, 400 μm or less, 300 μm or less, or 200 μm or less. By reducing the first height H1, the frictional resistance that the fluid F receives from the structure 20 can be reduced. The first height H1 is, for example, 20 μm or more, and may be 50 μm or more, or 100 μm or more.

[0198] In FIG. 32A, the symbol W represents the dimension of the disturbance structure 30 in the planar first direction E1. The dimension W may be measured at a position where the disturbance structure 30 contacts the base surface 21B. The dimension W may be determined in relation to the first height H1. W / H1, which is the ratio of the dimension W to the first height H1, is, for example, 0.3 or more, or may be 0.5 or more, or may be 0.7 or more. W / H1 is, for example, 3.0 or less, or may be 2.0 or less, or may be 1.5 or less.

[0199] In FIG. 32A, the symbol G represents the distance between two turbulence structures 30 arranged in the first planar direction E1. The distance G may be determined in relation to the first height H1. G / H1, which is the ratio of the distance G to the first height H1, is, for example, 1.0 or more, or may be 2.0 or more, or 3.0 or more. As a result, as shown in FIG. 32A, the fluid F1 deflected upward by colliding with the convex portion 301 can collide again with the convex portion 301 on the downstream side. This allows the fluid F flowing along the friction portion 25 to repeatedly collide with the turbulence structures 30. G / H1 is, for example, 12.0 or less, or may be 10.0 or less, or 8.0 or less. This sufficiently increases the frequency with which the fluid F collides with the turbulence structures 30. These factors promote mixing of the fluid F in the boundary layer between the fluid F and the surface of the object 10. Therefore, fluid separation can be suppressed.

[0200] As described above, it is preferable that the fluid F1 deflected upward by colliding with the upstream convex portion 301 collide again with the downstream convex portion 301. The base surface 21B located between two convex portions 301 aligned in the first planar direction E1 is also referred to as a valley region. In order for the fluid F1 to collide again with the downstream convex portion 301, it is preferable that no large protrusions are arranged in the valley region 21B1. This configuration prevents the valley region 21B1 from disrupting the flow of the fluid F1. The above-mentioned interval G corresponds to the dimension of the valley region 21B1 in the first planar direction E1.

[0201] 32B is a cross-sectional view showing a modified example of the structure 20. Small protrusions 34s may be arranged on the base surface 21B located between two convex portions 301 aligned in the first planar direction E1. If the height of the small protrusions 34s is small, the flow of the fluid F1 is hardly disturbed by the small protrusions 34s. Therefore, the fluid F1 that collides with the convex portion 301 on the upstream side can collide again with the convex portion 301 on the downstream side.

[0202] 32B, the symbol Hd represents the distance from the top of the convex portion 301 to the top of the small protrusion 34s in the normal direction of the base surface 21B. A preferable range of the distance Hd may be determined relative to the first height H1 of the convex portion 301. Hd / H1, which is the ratio of the distance Hd to the first height H1, is, for example, 0.90 or more, and may be 0.95 or more. Hd / H1, which is the ratio of the distance Hd to the first height H1, is, for example, 0.99 or less, and may be 0.98 or less.

[0203] The method for forming the disturbance structures 30 is not particularly limited. For example, the disturbance structures 30 may be formed by forming a resin layer on the base surface 21B of the base body 40 and then processing the resin layer using a mold such as a shaping roll. When the disturbance structures 30 are convex portions 301, the convex portions 301 may be formed by selectively applying a material constituting the convex portions 301 onto the base surface 21B by an inkjet method or the like. After performing a step of determining the shape of the disturbance structures 30, such as the convex portions 301, the disturbance structures 30 may be subjected to a curing treatment. For example, if the material of the disturbance structures 30 is UV-curable, the disturbance structures 30 may be irradiated with UV light.

[0204] Although not shown, the disturbing structure 30 may be configured integrally with the first substrate 41. "Integral" means that there is no interface between the disturbing structure 30 and the first substrate 41. For example, first, a first base material 41 having a thickness greater than the first height H1 may be prepared, and then the first base material 41 may be processed using a shaping roll or the like. This allows the disturbing structure 30 integrated with the first base material 41 to be obtained. For example, first, a mold is prepared. Then, a fluid raw material is poured into the mold. The raw material may contain a resin. The raw material may contain a resin and a solvent. Next, the raw material is solidified in the mold. For example, the raw material is heated to evaporate the solvent. As a result, the structure 20 is formed inside the mold. Thereafter, the structure 20 is removed from the mold. As a result, the disturbance structure 30 integrated with the first substrate 41 is obtained.

[0205] The manufacturing process of the structure 20 may include a step that is performed while the base body 40 is transported in a specific direction. For example, the coating step of selectively coating the material that forms the convex portions 301 onto the base surface 21B by an inkjet method or the like may be performed while the base body 40 is transported in the MD direction. For example, the step of irradiating the disturbance structure 30 with UV light may be performed while the base body 40 is transported in the MD direction. The MD direction is an abbreviation for machine direction. The MD direction is the direction in which the base body 40 is transported in the manufacturing process of the structure 20. The TD direction, which will be described later, is the transverse direction. The TD direction is perpendicular to the MD direction.

[0206] 32C is a plan view showing an example of the relationship between the MD direction and TD direction of the structure 20 and the first planar direction E1 and second planar direction E2 of the object 10. The TD direction of the structure 20 may be parallel to the first planar direction E1 of the object 10. For example, the angle formed between the TD direction and the first planar direction E1 may be equal to or smaller than the first threshold value TH1 described above.

[0207] The MD direction of the structures 20 may be parallel to the second planar direction E2 of the object 10. For example, the angle formed between the MD direction and the second planar direction E2 may be equal to or smaller than the first threshold value TH1 described above.

[0208] The structure 20 may be configured so that the tensile modulus of the structure 20 in the MD direction is greater than the tensile modulus of the structure 20 in the TD direction. For example, the first substrate 41 or the second substrate 45 of the base body 40 of the structure 20 may be a stretched plastic film stretched in the MD direction. The first substrate 41 may be a uniaxially stretched plastic film stretched in the MD direction, or a biaxially stretched plastic film stretched in both the MD and TD directions. The biaxially stretched plastic film may be configured so that the tensile modulus of the structure 20 in the MD direction is greater than the tensile modulus of the structure 20 in the TD direction.

[0209] The tensile modulus of the structure 20 is measured at 23±2°C in accordance with JIS K 7161-1:2014. A test specimen is obtained by cutting the structure 20 into a rectangle having a width of 25 mm and a length of 150 mm. The distance between the pair of chucks holding the test specimen at the start of measurement is 75 mm, and the tensile speed is 50 mm / min. The gauge length is 75 mm. The rated capacity of the load cell used is 1 kN. The average value of the measured values ​​of three test specimens is used as the tensile modulus of the present application.

[0210] When measuring the tensile modulus of elasticity in the MD direction of structure 20, a test piece is cut out from structure 20 so that the length direction of the test piece is parallel to the MD direction. When measuring the tensile modulus of elasticity in the TD direction of structure 20, a test piece is cut out from structure 20 so that the length direction of the test piece is parallel to the TD direction.

[0211] The tensile modulus TE1 of the structure 20 in the MD direction is, for example, 22 MPa or more, or may be 25 MPa or more, or 28 MPa or more. The tensile modulus TE1 of the structure 20 in the MD direction is, for example, 60 MPa or less, or may be 50 MPa or less, or may be 45 MPa or less.

[0212] The tensile modulus TE2 of the structure 20 in the TD direction is, for example, 15 MPa or more, or may be 18 MPa or more, or 20 MPa or more. The tensile modulus TE2 of the structure 20 in the TD direction is, for example, 28 MPa or less, or may be 25 MPa or less, or may be 22 MPa or less.

[0213] The ratio TE1 / TE2, which is the ratio of the tensile modulus of elasticity in the MD direction TE1 to the tensile modulus of elasticity in the TD direction TE2, is, for example, 1.10 or more, or alternatively, 1.30 or more, or even 1.50 or more. TE1 / TE2 is, for example, 2.50 or less, or alternatively, 2.30 or less, or alternatively, 2.00 or less.

[0214] The structure 20 before being attached to the object 10 may include a separator 43 in contact with the adhesive layer 42, as in the first embodiment shown in FIG. 6C. The structure 20 may be distributed in a state in which the separator 43 is included. In the process of attaching the structure 20 to the object 10, the separator 43 is removed, and then the structure 20 is attached to the object 10.

[0215] Next, returning to FIG. 31 , the spacing G between the two disturbance structures 30 will be described. The spacing G does not have to be constant at each position in the planar first direction E1. For example, the spacing G may vary depending on the position in the planar first direction E1. For example, as shown in FIG. 31 , the spacing G1 between the disturbance structures 30 in the first region P1 may be larger than the spacing G2 between the disturbance structures 30 in the second region P2. As described above, the first region P1 is a region of the first surface 21 that includes the curved surface 211. The second region P2 is a region of the first surface 21 that is flatter than the first region P1.

[0216] The smaller the radius of curvature of the curved surface 211, the less likely it is that the fluid F1 deflected upward by colliding with the convex portion 301 will collide with the downstream convex portion 301. By increasing the spacing G1 of the turbulence structures 30 in the first region P1, the fluid F1 can be caused to repeatedly collide with the turbulence structures 30 even on the curved surface 211. G1 / G2, which is the ratio of the spacing G1 to the spacing G2, is, for example, 1.01 or more, or may be 1.03 or more, 1.05 or more, or 1.10 or more.

[0217] The positions, shapes, etc. of the components on the first surface 21 of the structure 20 when attached to the object 10 are measured using a laser displacement sensor. Based on the measurement results, the above-mentioned first surface direction E1, curvature angle θ, length S1, width S21, width S22, first height H1, spacing G, etc. are calculated.

[0218] 32D is a diagram for explaining a method for measuring the first height H1 and the gap G of the disturbance structure 30 of the friction portion 25. This measurement method is also used in the first embodiment described above.

[0219] When the structure 20 includes three or more friction portions 25, the average values ​​of the measurements of the nine measurement regions are used as the first height H1 and the spacing G in the present application. The nine measurement regions are located at friction portions 25A, 25B, and 25C, as shown in FIG. 32D . The friction portion 25A is located at the center of the structure 20 in the second planar direction E2. The friction portions 25B and 25C are located adjacent to the friction portion 25A in the second planar direction E2.

[0220] The friction portion 25A includes a first test region Sq1, a second test region Sq2, and a third test region Sq3. The first test region Sq1 is located a distance Sc in the planar first direction E1 from the upstream end of the friction portion 25 in the planar first direction E1. The third test region Sr3 is located a distance Sc in the planar first direction E1 from the downstream end of the friction portion 25 in the planar first direction E1. The distance Sc is determined relative to the length S1 of the friction portion 25. Specifically, the distance Sc is 0.1 × S1. The second test region Sq2 is located at the center of the friction portion 25 in the planar first direction E1. Each of the first test region Sq1, the second test region Sq2, and the third test region Sq3 includes five disturbance structures 30 aligned in the planar first direction E1. Therefore, 15 disturbance structures 30 are measured in one friction portion 25A. When the number of disturbance structures 30 included in one friction portion 25A is less than 15, all of the disturbance structures 30 are measured.

[0221] In the first test area Sq1, as shown in FIG. 32D, measurements are performed along a single scan line SL located at the center of the first test area Sq1 in the second planar direction E2 and parallel to the first planar direction E1. The single scan line SL overlaps five disturbance structures 30 aligned in the first planar direction E1. The average values ​​of the first height H1 and the spacing G measured along the single scan line SL are the measured values ​​of the first height H1 and the spacing G in the first test area Sq1.

[0222] In the second test area Sq2 and the third test area Sq3, similarly to the first test area Sq1, measurements are performed along one scan line SL parallel to the first planar direction E1.

[0223] Similar to the frictional portion 25A, the frictional portion 25B includes a first test region Sq1, a second test region Sq2, and a third test region Sq3. Similar to the frictional portion 25A, measurements are performed along a single scan line SL parallel to the first direction E1 in the first test region Sq1, the second test region Sq2, and the third test region Sq3 of the frictional portion 25B. Similar to the frictional portion 25A, the frictional portion 25C includes a first test region Sq1, a second test region Sq2, and a third test region Sq3. Similar to the frictional portion 25A, measurements are performed along a single scan line SL parallel to the first direction E1 in the first test region Sq1, the second test region Sq2, and the third test region Sq3 of the frictional portion 25C. The average values ​​of the measurements in the nine measurement regions located in the frictional portions 25A, 25B, and 25C are used as the first height H1 and the spacing G in the present application.

[0224] Although not shown, when the structure 20 has two friction sections 25, test areas are set in the two friction sections 25. Each of the two friction sections 25 includes a first test area Sq1, a second test area Sq2, and a third test area Sq3. Therefore, when the structure 20 has two friction sections 25, measurements are performed in six test areas. The average values ​​of the measured values ​​in the six test areas are used as the first height H1 and the gap G in this application.

[0225] Although not shown, when the structure 20 includes one friction section 25 as described below, a test area is set in the one friction section 25. The one friction section 25 includes a first test area Sq1, a second test area Sq2, and a third test area Sq3. Therefore, when the structure 20 includes one friction section 25, measurements are performed in three test areas. The average values ​​of the measured values ​​in the three test areas are used as the first height H1 and the gap G in the present application.

[0226] Next, the smooth portion 26 will be described. The smooth portion 26 may include the above-mentioned base surface 21B. The occupancy rate of the base surface 21B in the friction portion 25 is referred to as a first base ratio R1. The occupancy rate of the base surface 21B in the smooth portion 26 is referred to as a second base ratio R2. The second base ratio R2 is higher than the first base ratio R1. The second base ratio R2 is, for example, 70% or more, may be 80% or more, 90% or more, 95% or more, 99% or more, or may be 100%.

[0227] FIG. 33 is a plan view showing an example of a vortex generated in the structure 20. The friction portion 25 and the smooth portion 26 extend in the first planar direction E1. Therefore, as shown in FIG. 33, a vortex F2 of the fluid can be generated along the boundary line 27 between the friction portion 25 and the smooth portion 26. This can prevent separation of the fluid F. As shown in FIG. 33, the energy of the vortex F2 may increase toward the downstream side. This can further prevent separation of the fluid F.

[0228] FIG. 34 is a diagram showing an example of the state of fluid F flowing along the surface of object 10 having structure 20. In the example shown in FIG. 34, structure 20 is attached to curved portion 15 between front surface 11 and side surface 14. This makes it possible to prevent separation of fluid F at curved portion 15. This makes it possible to prevent a difference from occurring between the pressure that object 10 receives from fluid F on the upstream side of structure 20 and the pressure that object 10 receives from fluid F on the downstream side of structure 20. This makes it possible to reduce the pressure resistance that object 10 receives from fluid F.

[0229] 35 is a diagram showing an example of the state of fluid F flowing along the surface of object 100 in a comparative embodiment. Object 100 in the comparative embodiment does not include structure 20. Therefore, it is thought that fluid F separates from object 100 at curved portion 15, creating a dead water region F3 between fluid F and object 100. As a result, the dimension M of the forward projection area of ​​object 100 relative to fluid F increases by the amount of dead water region F3. Therefore, the pressure resistance that object 100 experiences from fluid F increases.

[0230] In contrast, in the present embodiment, the structure 20 can suppress separation of the fluid F at the curved portion 15. Therefore, as shown in Fig. 34, the dimension M of the forward projection area can be made smaller than in the comparative embodiment. This reduces the pressure resistance that the object 10 receives from the fluid F.

[0231] The second embodiment described above can be modified in various ways. Hereinafter, other embodiments will be described with reference to the drawings as necessary. In the following description and the drawings used in the following description, parts that can be configured similarly to the second embodiment described above will be designated by the same reference numerals as those used for the corresponding parts in the second embodiment described above. Duplicate descriptions will be omitted. Furthermore, if it is clear that the effects obtained in the second embodiment described above can also be obtained in other embodiments, the descriptions may be omitted.

[0232] (First Modification) Fig. 36 is a cross-sectional view showing the structure 20 in the first modified example. As shown in Fig. 36, the disturbance structure 30 may be recessed with respect to the base surface 21B in the thickness direction of the structure 20. Such a disturbance structure 30 is also referred to as a recess 302. By using the recess 302, an increase in frictional resistance caused by the structure 20 can be suppressed. Furthermore, damage to the disturbance structure 30 can be suppressed compared to when the protrusion 301 is used.

[0233] The recess 302 has a second depth H2 from the base surface 21B. The second depth H2 is, for example, 400 μm or less, and may be 300 μm or less, or 200 μm or less. By reducing the second depth H2, the frictional resistance that the fluid F receives from the structure 20 can be reduced. The second depth H2 is, for example, 20 μm or more, and may be 50 μm or more, or 100 μm or more.

[0234] (Second Modification) FIG. 37A is a plan view showing a structure 20 in a second modified example. As shown in FIG. 37A, one friction portion 25 may include multiple disturbance structures 30 aligned in the second planar direction E2. The distance U between two disturbance structures 30 aligned in the second planar direction E2 may be, for example, 5.0 mm or less, 3.0 mm or less, 1.0 mm or less, 0.5 mm or less, or 0.1 mm or less. The disturbance structures 30 are, for example, convex portions 301. According to the example shown in FIG. 37A, foreign matter such as dust can pass between the two disturbance structures 30 aligned in the second planar direction E2. This prevents foreign matter from accumulating in the friction portion 25. The disturbing structure 30 may be a recess 302 .

[0235] The interval U may be determined in relation to the width S22 of the smooth portion 26. U / S22, which is the ratio of the interval U to the width S22, is, for example, 1 / 5 or less, or may be 1 / 10 or less, or may be 1 / 20 or less.

[0236] 37B is a plan view showing an example of a friction portion 25 in a second modified example. The multiple disturbance structures 30 may be arranged so that a gap U between two disturbance structures 30 aligned in the second planar direction E2 is filled by another disturbance structure 30 when viewed along the first planar direction E1. The positions of the two disturbance structures 30 in the first planar direction E1 are different from the position of the other disturbance structure 30 in the first planar direction E1.

[0237] (Third Modification) 38A is a plan view showing the structure 20 in the third modified example. The friction portion 25 and the smooth portion 26 may be distinguished based on their arithmetic mean height and maximum height. The friction portion 25 has a first arithmetic mean height Sa1 and a first maximum height Sz1. The smooth portion 26 has a second arithmetic mean height Sa2 and a second maximum height Sz2. The arithmetic mean height and maximum height are measured using a laser microscope in accordance with ISO 25178.

[0238] The first arithmetic mean height Sa1 is greater than the second arithmetic mean height Sa2. The ratio Sa1 / Sa2 of the first arithmetic mean height Sa1 to the second arithmetic mean height Sa2 is, for example, 2.0 or more, or may be 3.0 or more, or 5.0 or more, or 10.0 or more. The first arithmetic mean height Sa1 is, for example, 1.0 μm or more, or may be 2.0 μm or more, or may be 5.0 μm or more. The first arithmetic mean height Sa1 is, for example, 200 μm or less, or may be 150 μm or less, or may be 100 μm or less.

[0239] The first maximum height Sz1 is greater than the second maximum height Sz2. The ratio Sz1 / Sz2 of the first maximum height Sz1 to the second maximum height Sz2 is, for example, 2.0 or more, and may be 3.0 or more, 5.0 or more, or 10.0 or more. The first maximum height Sz1 is, for example, 20 μm or more, 40 μm or more, or 80 μm or more. The first maximum height Sz1 is, for example, 400 μm or less, 300 μm or less, or 200 μm or less.

[0240] Sz1 / Sa1, which is the ratio of the first maximum height Sz1 to the first arithmetic mean height Sa1, may be, for example, 5 or more, 6 or more, or 7 or more. Sz1 / Sa1 may be, for example, 15 or less, 12 or less, or 10 or less. When Sz1 / Sa1 is within this range, the resistance that the friction portion 25 exerts on the fluid F can be increased. This can further enhance the effect of reducing the pressure resistance that the object 10 experiences from the fluid F.

[0241] 38B is a diagram illustrating a method for measuring the first arithmetic mean height and the first maximum height when the structure 20 has only one friction portion 25. The first arithmetic mean height and the first maximum height are measured in a state where the structure 20 is placed on a horizontal surface. The structure 20 used in a state where it is attached to the object 10 is peeled off from the object 10 before measurement.

[0242] The average values ​​of the measurements of the three test regions are used as the first arithmetic mean height and the first maximum height in this application. The three test regions include a first test region Sr1, a second test region Sr2, and a third test region Sr3, as shown in FIG. 38B. The first test region Sr1 is located at the end of the friction portion 25 on the upstream side in the planar first direction E1. The third test region Sr3 is located at the end of the friction portion 25 on the downstream side in the planar first direction E1. The second test region Sr2 is located at the center of the friction portion 25 in the planar first direction E1. The first test region Sr1, the second test region Sr2, and the third test region Sr3 are all located at the center of the friction portion 25 in the planar second direction E2.

[0243] When the structure 20 has a plurality of friction portions 25 arranged in the second planar direction E2, the first arithmetic mean height and the first maximum height are measured at the friction portion 25 closest to the center of the structure 20 in the second direction E2.

[0244] In the first test region Sr1, as shown in FIG. 38B, measurements are performed along ten scan lines SL parallel to the planar first direction E1. The ten scan lines SL are arranged at equal intervals in the planar second direction E2. The interval Sp between two adjacent scan lines SL is 0.2 mm. The length Sd of the scan lines SL is also referred to as the evaluation length. The length Sd is determined relative to the length S1 of the friction portion 25. Specifically, the length Sd of the scan lines SL is 0.1 × S1. The first arithmetic mean height and the first maximum height measured along the ten scan lines SL are the measurement values ​​of the first arithmetic mean height and the first maximum height in the first test region Sr1.

[0245] In the second test area Sr2 and the third test area Sr3, measurements are also performed along ten scan lines SL parallel to the first planar direction E1, similar to the first test area Sr1.

[0246] FIG. 38C is a diagram illustrating a method for measuring the first arithmetic mean height and the first maximum height when the structure 20 includes three or more friction portions 25. As shown in FIG. 38C, test regions are set in three friction portions 25 located at the center in the second planar direction E2. Each of the three friction portions 25 includes a first test region Sr1, a second test region Sr2, and a third test region Sr3, similar to the example shown in FIG. 38B. Therefore, in the example shown in FIG. 38C, measurements are performed in nine test regions. The average values ​​of the measurements in the nine test regions are used as the first arithmetic mean height and the first maximum height in this application.

[0247] Although not shown, when the structure 20 has two friction sections 25, test areas are set in the two friction sections 25. Each of the two friction sections 25 includes a first test area Sr1, a second test area Sr2, and a third test area Sr3. Therefore, when the structure 20 has two friction sections 25, measurements are performed in six test areas. The average values ​​of the measured values ​​in the six test areas are used as the first arithmetic mean height and the first maximum height in this application.

[0248] (Fourth Modification) FIG. 39 is a plan view showing a structure 20 in a fourth modified example. As shown in FIG. 39, the smooth portion 26 may include a rectifying structure 35 extending in the planar first direction E1. The rectifying structure 35 rectifies the fluid F so that the fluid F flows along the planar first direction E1. The rectifying structure 35 is, for example, a groove extending along the planar first direction E1. By providing the rectifying structure 35, the resistance that the smooth portion 26 exerts on the fluid F can be reduced. As shown in FIG. 39, one smooth portion 26 may include a plurality of rectifying structures 35 aligned in the planar second direction E2.

[0249] (Fifth Modification) Fig. 40A is a plan view showing structure 20 in a fifth modified example. Structure 20 includes friction portion 25, but may not include smooth portion 26. For example, as shown in Fig. 40A, friction portion 25 may extend across the entire area of ​​structure 20 in second planar direction E2.

[0250] The friction portion 25 may be configured to disrupt the flow of the fluid F, as in the above-described embodiment. For example, the friction portion 25 may include a disruption structure 30. The disruption structure 30 may extend continuously from a first end of the structure 20 in the planar second direction E2 to a second end of the structure 20 located opposite the first end in the planar second direction E2. For example, as shown in FIG. 40A , the disruption structure 30 may extend continuously along a direction perpendicular to the planar first direction E1.

[0251] The disturbing structure 30 may include a convex portion 301. In this modification, the structure of the convex portion 301 described in the above embodiment can also be employed.

[0252] FIG. 40B is a plan view showing an example of a vortex generated in the structure 20 of FIG. 40A. The convex portions 301 of the disturbance structures 30 of the friction portion 25 extend along a direction intersecting the first planar direction E1. For example, the convex portions 301 of the disturbance structures 30 extend along a direction perpendicular to the first planar direction E1. Therefore, the fluid F1 collides with the convex portions 301 of the disturbance structures 30, generating a fluid vortex F2. This can prevent separation of the fluid F. This can prevent a difference from occurring between the pressure that the object 10 receives from the fluid F on the upstream side of the structure 20 and the pressure that the object 10 receives from the fluid on the downstream side of the structure 20. This can reduce the pressure resistance that the object 10 receives from the fluid F.

[0253] The disturbance structure 30 may include a recess 302. In this case, the disturbance structure 30 can also generate a vortex F2 in the fluid, thereby suppressing separation of the fluid F. In this modification, the structure of the recess 302 described in the first modification can also be adopted.

[0254] 41A, the width S21 of the friction portion 25 may be greater than the length S1 of the friction portion 25. In other words, the length S1 of the friction portion 25 may be less than the width S21 of the friction portion 25. When the structure 20 has a form that allows it to be attached to the object 10, the efficiency of the attachment work can be improved by reducing the length S1 of the friction portion 25.

[0255] Fig. 41B is a plan view showing an example of a vortex generated in the structure 20 of Fig. 41A. In the structure 20 shown in Fig. 41A and Fig. 41B, the fluid F1 collides with the convex portions 301 of the disturbance structure 30, generating a vortex F2 of the fluid. This makes it possible to suppress separation of the fluid F.

[0256] As shown in Fig. 42, the friction portion 25 may include a plurality of disturbance structures 30 arranged in the second planar direction E2. In this case, a vortex F2 of the fluid can be generated. This can suppress separation of the fluid F. In this modification, the structure of the disturbance structures 30 described in the second modification and shown in Figs. 37A and 37B can also be used.

[0257] As shown in FIG. 43 , the structure 20 may include a convex portion 301 that extends continuously along the first planar direction E1. In this case, the convex portion 301 rectifies the fluid F so that the fluid F flows along the first planar direction E1. Although not shown, the friction portion 25 may include a concave portion 302 that extends continuously along the first planar direction E1. The structure 20 shown in FIG. 43 can reduce the frictional resistance that the fluid F experiences from the structure 20. Therefore, the resistance that the fluid F experiences from the object 10 can be reduced compared to when the structure 20 is not provided on the object 10.

[0258] (Sixth Modification) Fig. 44 is a plan view showing a modified example of the object 10. As shown in Fig. 44, the structure 20 may be attached to the curved portion 15 located between the rear surface 12 and the side surface 14. This makes it possible to prevent separation of the fluid F at the rear curved portion 15. For example, the separation point is located further downstream than when the structure 20 is not provided. The separation point is the position where separation of the fluid F from the object 10 occurs.

[0259] (Seventh Modification) Fig. 45 is a plan view showing a modified example of the object 10. The structure 20 may be attached to the curved portion 15 adjacent to the upper surface 13. For example, as shown in Fig. 45, the structure 20 may be attached to the curved portion 15 located between the rear surface 12 and the upper surface 13. This makes it possible to prevent separation of the fluid F from occurring at the curved portion 15 adjacent to the upper surface 13.

[0260] (Eighth Modification) In the above-described embodiment, an example has been described in which the structure 20 is attached to the curved portion 15 of the object 10. However, the relationship between the structure 20 and the object 10 is not particularly limited. For example, as shown in FIG. 46 , the structure 20 may be a component that is provided on the object 10 when the object 10 is in circulation. For example, the structure 20 may be a part that constitutes the curved portion 15 of the object 10. For example, if the object 10 is a car, the structure 20 may be a single part that constitutes the object 10, such as a door visor. In other words, a single part that constitutes the object 10 may have the features of the structure 20, such as the curved surface 211, the friction portion 25, and the smooth portion 26. In this case, the structure 20 may be a molded product produced by, for example, injection molding a resin.

[0261] (Ninth Variation) In the above-described embodiment and modified examples, an example has been shown in which the object 10 equipped with the structure 20 is a large vehicle such as a bus. However, as long as the object 10 comes into contact with the fluid F, the size of the object 10 is not particularly limited. For example, as shown in Figs. 47 and 48, the object 10 may be a passenger car. Figs. 47 and 48 are a side view and a perspective view showing an example of a passenger car equipped with the structure 20.

[0262] As shown in Figures 47 and 48, the object 10 made of a passenger car may include a curved portion 15 located on the upper surface 13 of the rear of the object 10. In this case, the object 10 may be provided with a structure 20 located on the curved portion 15 of the upper surface 13 of the rear. This makes it possible to prevent the fluid F from separating from the object 10 at the rear of the object 10. For example, as shown in Figure 47, the separation point 18 where separation of the fluid F from the object 10 occurs can be positioned further downstream.

[0263] When the fluid F separates from the object 10, a dead water region 19 may occur between the fluid F and the object 10. When the dead water region 19 occurs, the pressure resistance that the object 10 experiences from the fluid F increases. According to the examples shown in FIGS. 47 and 48, the separation point 18 can be shifted downstream compared to when the object 10 does not have the structure 20, thereby preventing the dead water region 19 from occurring. This reduces the pressure resistance that the object 10 experiences from the fluid F.

[0264] (Tenth Modification) 49 is a perspective view showing an object 10 according to a tenth modified example. The object 10, which is a passenger car, may include a curved portion 15 located on a rear side surface 14. The curved portion 15 may be formed, for example, in a part of the side surface 14 adjacent to the top surface 13. In this case, the object 10 may include a structure 20 located on the curved portion 15 of the rear side surface 14.

[0265] The object 10, which is a passenger car, may include a structure 20 located at each of the curved portions 15 of the two rear side surfaces 14. The object 10, which is a passenger car, may further include a structure 20 located at the curved portion 15 of the rear upper surface 13. In this case, the object 10, which is a passenger car, includes three structures 20.

[0266] (Eleventh Modification) The structure 20 located at the bending portion 15 may have the features of the structure 20 described in the first embodiment or its modification above. In other words, the structure 20 described in the first embodiment or its modification above may be attached to the bending portion 15. Alternatively, the structure 20 described in the first embodiment or its modification above may be a component that constitutes the bending portion 15 of the object 10.

[0267] For example, the structure 20 located in the curved portion 15 may include the above-mentioned plurality of first guiding structures 31 described in the first embodiment or its modification. For example, the disturbing structure 30 of the structure 20 located in the curved portion 15 may include the above-mentioned plurality of first guiding structures 31 described in the above-mentioned first embodiment or its modification and the above-mentioned plurality of second guiding structures 32.

[0268] (Other variations) In the above-described embodiment, an example has been shown in which the object 10 equipped with the structure 20 is a mobile object that can move itself. However, the object 10 is not particularly limited as long as the object 10 is in contact with the fluid F. For example, the object 10 may be a fixed object that does not move itself but controls the flow of the fluid F.

[0269] The moving body may be, for example, an automobile such as a passenger car, truck, or bus; a railway vehicle such as a train, bullet train, or locomotive; an aircraft such as an airplane, helicopter, or drone; or a bicycle. These moving bodies move through the atmosphere. The fluid in contact with the moving body is air. The object 10 having the structure 20 may be a part of these moving bodies. For example, the object 10 may be a component that constitutes the moving body, such as a housing.

[0270] The fixed object may be, for example, a pipe such as a duct or gas pipe; a windmill blade; or an air outlet or louver of an air conditioning device such as an air conditioner. These fixed objects control the flow of gas. The object 10 having the structure 20 may be a part of these fixed objects. For example, the object 10 may be a component that constitutes the surface of these fixed objects.

[0271] [Example] Next, the present disclosure will be described in more detail with reference to examples. However, the present disclosure is not limited to the following examples as long as it does not depart from the gist of the disclosure.

[0272] Example B1 The effect of the structure 20 was verified through a wind tunnel experiment in which an airflow was made to collide with the object 10 to which the structure 20 was attached. A 1 / 10-size model of a 10-ton truck was used as the object 10. The object 10 includes a curved portion 15 located between the front surface 11 and the top surface 13. The radius of curvature of the curved portion 15 is 25 mm. After colliding with the front surface 11, part of the airflow flows backward along the top surface 13. While part of the airflow travels from the front surface 11 to the top surface 13, part of the airflow flows along the curved portion 15.

[0273] The structure 20 attached to the curved portion 15 located between the front surface 11 and the upper surface 13 is configured as follows: The friction portion 25 and the smooth portion 26 extend along the curved portion 15 from the front surface 11 toward the upper surface 13. Length of friction part 25 S1: 210mm Length of smooth section 26: 210mm Width of friction part 25 S21: 7mm Width of smooth part 26 S22: 7mm Height H1 of the protrusion 301 of the friction portion 25: 0.08 mm Dimension W of the protrusion 301 of the friction part 25: 0.08 mm Distance G between two protrusions 301: 0.56 mm

[0274] The air resistance coefficient was measured when the airflow speed was set to 10 m / s, 15 m / s, 20 m / s, 25 m / s, and 30 m / s. The air resistance coefficient is also called the Cd value. The air resistance coefficient was calculated based on the drag force acting on the object 10 due to the airflow. The drag force was measured using a load cell via a wire fixed to the object 10. The results are shown in Figures 50 and 51.

[0275] (Example B2) The air resistance coefficient was measured in the same manner as in Example B1, except that the height H1, dimension W, and interval G of the protrusions 301 were changed as follows. The results are shown in Figures 50 and 51. Height H1 of the protrusion 301 of the friction portion 25: 0.16 mm Dimension W of the protrusion 301 of the friction portion 25: 0.16 mm Distance G between two protrusions 301: 1.12 mm

[0276] (Example B3) The air resistance coefficient was measured in the same manner as in Example B1, except that the height H1, dimension W, and interval G of the protrusions 301 were changed as follows. The results are shown in Figures 50 and 51. Height H1 of the protrusion 301 of the friction portion 25: 0.28 mm Dimension W of the protrusion 301 of the friction part 25: 0.28 mm Distance G between two protrusions 301: 1.96 mm

[0277] (Comparative Example B1) The air resistance coefficient was measured in the same manner as in Example B1, except that the structure 20 was not attached to the curved portion 15 of the object 10. The results are shown in FIGS.

[0278] As can be seen from the comparison between Examples B1 to B3 and Comparative Example B1, by attaching the structure 20 to the object 10, the air resistance coefficient could be reduced.

[0279] It was observed that the smaller the height H1 of the convex portion 301, the more pronounced the effect when the wind speed was high.

[0280] (Example B11) The effect of the structure 20 was verified through a wind tunnel experiment in which an airflow was made to collide with the object 10 to which the structure 20 was attached. A 1 / 10-size model of a 10-ton truck was used as the object 10. Specifically, the object 10 has a length of 1250 mm, a width of 260 mm, and a height of 387 mm. The object 10 includes one curved portion 15 located between the front surface 11 and the top surface 13, and two curved portions located between the front surface 11 and the two side surfaces 14. The curved portions 15 have a radius of curvature of 25 mm. The structure 20 is attached to each of the three curved portions 15.

[0281] The structure 20 attached to the curved portion 15 is configured as follows. Length of friction part 25 S1: 210mm Width of friction part 25 S21: 7mm Width of smooth part 26 S22: 7mm The shape of the disturbance structure 30 of the friction portion 25: a convex portion extending in a direction perpendicular to the first direction E1 Height H1 of the protrusion 301: 0.02 mm Dimension of convex part 301 W: 0.02 mm Distance G between two protrusions 301: 0.14 mm

[0282] The air resistance coefficient was measured when the airflow speed was set to 10 m / s, 15 m / s, 20 m / s, 25 m / s, and 30 m / s. The results are shown in Figures 52 and 53. The "Cd value" shown in Figure 52 is the Cd value when the wind speed was 25 m / s.

[0283] (Examples B12 to B16 and Comparative Example B12) The air resistance coefficient was measured in the same manner as in Example B11, except that the height H1, dimension W, and interval G of the convex portions 301 were changed as shown in Fig. 52. The results are shown in Fig. 52 and Fig. 53.

[0284] (Comparative Example B11) The air resistance coefficient was measured in the same manner as in Example B11, except that the structure 20 was not attached to the curved portion 15 of the object 10. The results are shown in Figs. 52 and 53.

[0285] As can be seen from a comparison between Examples B11 to B16 and Comparative Example B11, the air resistance coefficient could be reduced by attaching structure 20 including protrusions 301 with a height H1 of 1.0 mm or less to object 10. On the other hand, as can be seen from a comparison between Comparative Example B12 and Comparative Example B11, when structure 20 including protrusions 301 with a height H1 of 2.0 mm or more was attached to object 10, the air resistance coefficient increased. It is thought that when height H1 of protrusions 301 becomes too large, frictional resistance becomes larger than pressure resistance, and the resistance that object 10 receives from the fluid increases.

[0286] (Examples B21 to B23) The air resistance coefficient was measured in the same manner as in Example B13, except that the length S1 of the friction portion 25 was changed as shown in Fig. 54. The results are shown in Figs.

[0287] As can be seen from a comparison between Examples B21 to B23 and Comparative Example B11, when the length S1 of the friction portion 25 was 25 mm or more, the resistance that the object 10 received from the fluid was reduced by the structure 20. Almost no dependency of the air resistance coefficient on the length S1 was observed.

[0288] (Example B31) A wind tunnel experiment was carried out using a passenger car model shown in Fig. 49 as the object 10. The object 10 includes one curved portion 15 located between the rear surface 12 and the top surface 13, and two curved portions located between the rear surface 12 and the two side surfaces 14. A structure 20 is attached to each of the three curved portions 15.

[0289] The structure 20 attached to the curved portion 15 is configured as follows. Length of structure 20: 840mm Width of friction part 25 S21: 20mm Width of smooth part 26 S22: 20mm The shape of the disturbance structure 30 of the friction portion 25: a convex portion extending in a direction perpendicular to the first direction E1 Height H1 of the protrusion 301: 0.10 mm Dimension of convex part 301 W: 0.10 mm Distance G between two protrusions 301: 0.70 mm

[0290] The air resistance coefficient was measured when the airflow speed was set to 10 m / s, 20 m / s, and 30 m / s. The results are shown in Figures 56 and 57.

[0291] (Comparative example B31) The air resistance coefficient was measured in the same manner as in Example B31, except that a structure 20 consisting only of a smooth portion 26 was used. The results are shown in Figs. 56 and 57.

[0292] (Comparative Example B32) The air resistance coefficient was measured in the same manner as in Example B31, except that the structure 20 was not attached to the curved portion 15 of the object 10. The results are shown in Figs. 56 and 57.

[0293] As can be seen from the comparison between Example B31 and Comparative Examples B31 and B32, the air resistance coefficient could be reduced by attaching structure 20 including friction portion 25 and smooth portion 26 to object 10, which was a passenger car.

[0294] (Example B41~B50) The air resistance coefficient was measured in the same manner as in Example B11, except that a structure 20 including a friction portion 25 but not a smooth portion 26 was used. The results are shown in FIG. 58. In the "Direction of convex portions" row in FIG. 58, "E2" means that the convex portions extended in the planar second direction E2 perpendicular to the planar first direction E1, as shown in FIG. 40. In the "Direction of convex portions" row in FIG. 58, "E1" means that the convex portions 301 extended in the planar first direction E1, as shown in FIG. 43. In the "Direction of convex portions" row in FIG. 58, "-" means that the friction portion 25 included multiple convex portions 301 aligned in the planar second direction E2, as shown in FIG. 42.

[0295] (Example B51) The air resistance coefficient was measured in the same manner as in Example B41, except that the structure 20 was not attached to the curved portion 15 of the object 10. The results are shown in FIG.

[0296] The measurement results of the air resistance coefficient for Examples B41 to B45 and Example B51 are shown in Figure 59. In Examples B41 to B45, the height H1 of the convex portion was approximately 0.15 mm. As shown in Examples B41 to B45, there was a tendency for the air resistance coefficient value to reach a minimum value at specific wind speeds. The wind speed at which the minimum value appeared depended on the spacing G between the convex portions 301.

[0297] The measurement results of the air resistance coefficient for Examples B46 to B48 and Example B51 are shown in Figure 60. In Examples B46 to B48, the height H1 of the convex portion is approximately 0.20 mm. As shown in Examples B46 to B48, there was a tendency for the air resistance coefficient value to reach a minimum value at specific wind speeds. The wind speed at which the minimum value appeared depended on the spacing G between the convex portions 301.

[0298] FIG. 61 shows the measurement results of the air resistance coefficient for Example B41 and Examples B49 to B51. In Example B49, the convex portions 301 extend in the first planar direction E1 as shown in FIG. 43. The structure 20 of Example B49 was also able to reduce the air resistance coefficient. In Example B50, the multiple convex portions 301 are aligned in the second planar direction E2 as shown in FIG. 42. The structure 20 of Example B50 was also able to reduce the air resistance coefficient.

[0299] (Example B61) "IJ180 mc-114" manufactured by 3M was prepared. IJ180 mc-114 includes a transparent substrate made of vinyl chloride resin. IJ180 mc-114 functions as the second substrate 45.

[0300] A laminate film "DOL1460Z" manufactured by Avery Dennison was prepared. DOL1460Z includes a vinyl chloride resin film, an adhesive layer, and a release paper in this order. The vinyl chloride resin film of DOL1460Z functions as the first substrate 41.

[0301] After peeling off the release paper from DOL1460Z, DOL1460Z was laminated onto IJ180 mc-114. Next, ink was ejected onto the vinyl chloride resin film of DOL1460Z using a UV inkjet device. The ink used was "Seikabeam HT509" manufactured by Dainichi Seika Chemicals Co., Ltd. The ink ejected onto the vinyl chloride resin film was cured by UV irradiation. This resulted in the formation of multiple disturbance structures 30 as shown in Figure 32C. The disturbance structures 30 extend parallel to the MD direction. The specific configuration of a structure 20 having multiple disturbance structures 30 is shown below. Width of friction part 25 S21: 7mm Width of smooth part 26 S22: 7mm First height H1 of the disturbance structure 30: 0.14 mm Pitch P11 of the disturbing structures 30 in the first direction E1: 1.12 mm

[0302] The tensile modulus of the structure 20 was measured using a universal material testing machine "Instron 5565." The tensile modulus of the structure 20 in the MD direction was 39.8 MPa. The tensile modulus of the structure 20 in the TD direction was 20.3 MPa.

[0303] (Example B62) As in Example B61, DOL1460Z was laminated onto IJ180 mc-114. Next, a UV-curable resin composition was applied onto the vinyl chloride resin film of DOL1460Z. Seikabeam HT509 manufactured by Dainichiseika Chemicals Co., Ltd. was used as the UV-curable resin. Next, a mold was pressed against the film of UV-curable resin composition to form a film of UV-curable resin composition. The molded film of UV-curable resin composition was cured by UV irradiation. This resulted in the formation of multiple disturbance structures 30 shown in Figure 32C. The configuration of the disturbance structures 30 was the same as in Example B61.

[0304] The tensile modulus of the structure 20 was measured using a universal material testing machine "Instron 5565." The tensile modulus of the structure 20 in the MD direction was 29.8 MPa. The tensile modulus of the structure 20 in the TD direction was 21.1 MPa.

[0305] (Example B63) As in Example B61, DOL1460Z was laminated to IJ180 mc-114.

[0306] The tensile modulus of a laminate consisting of IJ180 mc-114 and DOL1460Z was measured using a universal material testing machine "Instron 5565." The tensile modulus of the laminate in the MD direction was 10.7 MPa. The tensile modulus of the laminate in the TD direction was 10.4 MPa. [Explanation of symbols]

[0307] 10 objects 11 Front 12 Rear 13 Top side 14 Side 15 Curved section 161 Front window 162 Rear window 18 Peeling point 19 Dead Water Area 20 Structure 21 Page 1 21B base surface 21B1 Valley area P1 1st area 22 Side 2 25 Friction part 26 Smooth section 26A 1st smooth section 26B 2nd smooth section 27 Borderline 30 Disturbance Structure 301 Convex part 302 recess 31 1st guidance structure 311 First end part φ1 1st inclination angle 312 3rd end part 313 1st upstream surface 314 1st downstream surface 32 Second guidance structure 321 Second end part φ2 2nd inclination angle 322 4th end part 323 2nd upstream surface 324 2nd downstream surface 33 Connection part 34s small protrusion 35 Rectifier structure 40 Base Body 41 First base material 42 Adhesive layer 43 Separator 44 Printing layer 45 Second base material 46 Adhesive layer E1 side 1st direction E2 surface 2nd direction F fluid

Claims

1. A structure for reducing fluid resistance, a first surface in contact with the fluid; a plurality of friction portions located on the first surface and extending in a first direction along the first surface; a plurality of smooth portions located on the first surface and extending in a first direction along the first surface; the plurality of friction portions and the plurality of smooth portions are alternately arranged along a second surface direction intersecting the first surface direction, the plurality of smooth portions include a first smooth portion adjacent to the friction portion in the second surface direction, the friction portion includes a plurality of first guide structures aligned in the first direction of the surface and configured to guide a fluid to the first smooth portion, the first guide structure includes a first end portion extending toward the first smooth portion; the first end portion has a first inclination angle greater than 0° and less than 90° with respect to the first surface direction; The friction portion has a length of 50 mm or more and 1000 mm or less in the first direction of the surface.

2. the plurality of smooth portions include a second smooth portion adjacent to the friction portion in the second surface direction, the friction portion is located between the first smooth portion and the second smooth portion in the second surface direction, the friction portion includes a plurality of second guide structures aligned in the first direction of the surface and configured to guide the fluid to the second smooth portion, the second guide structure includes a second end portion extending toward the second smooth portion; The structure of claim 1 , wherein the second end portion has a second tilt angle with respect to the first direction of the surface that is greater than 0° and less than 90°.

3. The structure according to claim 2 , wherein the friction portion includes a connection portion that connects the first guide structure and the second guide structure.

4. the first surface includes a base surface; the first guide structure protrudes from the base surface in a thickness direction of the structure, the first guiding structure has a first height from the base surface; the first height is equal to or greater than 20 μm and equal to or less than 400 μm, a ratio of a distance between two of the first guide structures arranged in the first direction of the surface to the first height is equal to or greater than 1.0 and equal to or less than 9.0; 4. The structure according to claim 1, wherein a ratio of a dimension of the first guide structure in the first direction of the surface to the first height is 0.3 or more and 3.0 or less.

5. The structure according to any one of claims 1 to 3, wherein the friction portion has a width of 0.2 mm or more and 50 mm or less in a direction perpendicular to the first surface direction.

6. the first surface includes a base surface; The structure according to any one of claims 1 to 3, wherein the first guide structure protrudes from the base surface in a thickness direction of the structure.

7. the first guiding structure has a first height from the base surface; The structure according to claim 6 , wherein the first height is equal to or greater than 20 μm and equal to or less than 1.0 mm.

8. The structure according to claim 7 , wherein a ratio of a spacing between the plurality of first guide structures in a direction perpendicular to a direction in which the first guide structures extend to the first height is equal to or greater than 1.0 and equal to or less than 12.

0.

9. the first surface includes a base surface; The structure according to any one of claims 1 to 3, wherein the first guide structure is recessed relative to the base surface in a thickness direction of the structure.

10. the friction portion includes the base surface at a first base ratio; The structure of claim 6 , wherein the first smooth portion includes the base surface at a second base ratio that is higher than the first base ratio.

11. The structure according to any one of claims 1 to 3, wherein the first guiding structure extends linearly toward the first smooth portion.

12. the first guiding structure has a deviation distance of 0.1 mm or less; the deviation distance is a maximum value of a distance between a first virtual straight line and the first guiding structure in the first direction of the surface, The structure described in claim 11, wherein the first virtual straight line is a straight line passing through a portion of the first guiding structure located most upstream in the first direction of the surface and a portion of the first guiding structure located most downstream in the first direction of the surface.

13. the first surface includes a curved surface; The structure according to any one of claims 1 to 3, wherein the friction portion and the first smooth portion are located on the curved surface.

14. The structure according to claim 13 , wherein a boundary line between the friction portion and the first smooth portion extends parallel to the first surface direction.

15. An object in contact with a fluid, An object comprising the structure according to any one of claims 1 to 3 located on the surface of the object.

16. the object comprises a curved portion; 16. The object of claim 15, wherein the structure is located at the curved portion.

17. An object in contact with a fluid, An object comprising a part made of the structure according to any one of claims 1 to 3.

18. The object according to claim 15 , wherein the object is a moving object or part of a moving object.

19. The object according to claim 17, wherein the object is a moving object or part of a moving object.

20. The object of claim 15 , wherein the object controls the flow of a fluid.

21. 20. The object of claim 17, wherein the object controls the flow of a fluid.

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