Porous structure for reducing aerodynamic noise, and method for manufacturing a porous structure for reducing aerodynamic noise

Abstract

To provide technology, etc. that can easily create structures with structures suitable for aerodynamic noise reduction.SOLUTION: In the porous structure according to this technology, data for a porous structure with a structure suitable for reducing aerodynamic noise under the corresponding conditions is created based on the software for creating mesh structures used in numerical fluid dynamics, and the porous structure is created by a three-dimensional printer based on the data created.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present technology relates to technologies such as porous structures for aerodynamic noise reduction. Background Art

[0002] It has been conventionally known that structures for reducing aerodynamic noise are attached to surfaces of objects and the like.

[0003] For example, Patent Document 1 below discloses that aerodynamic noise can be reduced by attaching a porous body to each part of railway vehicles, automobiles, aircrafts and the like. Prior Art Documents Patent Documents

[0004] Patent Document 1 Japanese Unexamined Patent Publication No. 2008-136332 Summary of the Invention Problem to be Solved by the Invention

[0005] In such fields, there is a demand for technologies that can easily produce a structure having a structure suitable for aerodynamic noise reduction.

[0006] In view of the above circumstances, an object of the present technology is to provide a technology or the like that can easily produce a structure having a structure suitable for aerodynamic noise reduction. Means for Solving the Problem

[0007] A porous structure according to the present technology is produced by a three-dimensional printer based on generated data of the porous structure, wherein the data having a structure suitable for aerodynamic noise reduction under corresponding conditions is generated based on mesh structure generation software used in computational fluid dynamics.

[0008] This makes it possible to easily create porous structures with a structure suitable for reducing aerodynamic noise.

[0009] The above porous structure may be composed of a mesh in which hexahedral elements are used as constituent elements.

[0010] In the porous structure described above, the hexahedral element may be composed of a tetrahedral element divided into multiple hexahedral elements.

[0011] In the porous structure described above, when the tetrahedral element is divided into a plurality of hexahedral elements, three additional columnar elements may be added to each of the four triangles in the tetrahedral element, connecting the three first points of the three columnar elements constituting the triangle with a second point inside the triangle.

[0012] In the porous structure described above, when the tetrahedral element is divided into a plurality of hexahedral elements, four additional columnar elements may be added, connecting the four second points inside the four triangles of the tetrahedral element with a third point inside the tetrahedral element.

[0013] The porous structure described above may be manufactured to match the shape of the object to which the porous structure is attached.

[0014] The porous structure described above may include a mounting base for attaching the porous structure to an object.

[0015] In the above-described porous structure, the software may generate preliminary data for a porous structure in which tetrahedral elements are the constituent units, and the tetrahedral elements in the preliminary data may be divided into a plurality of hexahedral elements to generate data for the porous structure in which hexahedral elements are the constituent units.

[0016] In the above porous structure, in said software, when said tetrahedral element is divided into a plurality of hexahedral elements, for each of the four triangles in said tetrahedral element, three pillar elements connecting three first points on three pillar elements constituting said triangle and one second point inside said triangle may be added.

[0017] In the above porous structure, in said software, when said tetrahedral element is divided into a plurality of hexahedral elements, four pillar elements connecting said four second points inside said four triangles in said tetrahedral element and one third point inside said tetrahedral element may be further added.

[0018] In the above porous structure, said software may be MEGG3D.

[0019] The above porous structure may be used for aircraft.

[0020] The porous structure for aerodynamic noise reduction according to the present technology is a porous structure formed by a mesh having hexahedral elements as constituent elements, wherein said hexahedral elements are formed by dividing tetrahedral elements into a plurality of hexahedral elements.

[0021] A method for manufacturing a porous structure according to the present technology comprises generating data of a porous structure having a structure suitable for reducing aerodynamic noise under corresponding conditions based on mesh structure generation software used in computational fluid dynamics, generating the porous structure by a three-dimensional printer based on the generated said data.

Effects of the Invention

[0022] As described above, according to the present technology, there can be provided a technology or the like that can easily produce a porous structure having a structure suitable for reducing aerodynamic noise.

Brief Description of Drawings

[0023] [Figure 1]It is a diagram illustrating a method for manufacturing a porous structure. [Figure 2] It is a diagram illustrating how tetrahedral elements are divided into hexahedral elements in MEGG3D. [Figure 3] It is a diagram illustrating a porous structure produced by a three-dimensional printer. [Figure 4] It is a perspective view showing an example where the porous structure is formed of metal. [Figure 5] It is a top view showing an example where the porous structure is formed of metal. [Figure 6] It is a diagram showing an example of a porous structure. [Figure 7] It is a diagram showing the distribution of lengths of pillar elements in hexahedral elements. [Figure 8] It is a diagram showing the state when the porous structure is attached to an aircraft. [Figure 9] It is a diagram showing a second comparative example. [Figure 10] It is a diagram showing a third comparative example. MODE FOR CARRYING OUT THE INVENTION

[0024] Hereinafter, embodiments according to the present technology will be described with reference to the drawings.

[0025] <<First Embodiment>> <Method for Manufacturing Porous Structure 10> First, a method for manufacturing the porous structure 10 according to the first embodiment of the present technology will be described. Fig. 1 is a diagram illustrating the method for manufacturing the porous structure 10.

[0026] As shown in Fig. 1, first, data on the body shape (outer shape) of the porous structure 10 (three-dimensional model) to be produced is generated (upper left side of Fig. 1). In the example herein, as the porous structure 10 to be attached to a cylinder elongated in one direction (not shown), a cylindrical porous structure 10 having a predetermined thickness is exemplified.

[0027] The shape of the porous structure 10 can be any shape. In this embodiment, as will be described later, a 3D printer is used, so the shape of the porous structure 10 can typically be any shape, and any desired shape can be easily created.

[0028] Once the shape (outer shape) data of the porous structure 10 body is created, this data is then output to MEGG3D as an STL (Stereolithography) file. MEGG3D is software developed by JAXA (Japan Aerospace Exploration Agency: registered trademark) for creating mesh structures (structures in which column elements are connected to form a mesh) used in computational fluid dynamics (CFD). MEGG3D is not the only software used to create mesh structures for computational fluid dynamics; other software may also be used.

[0029] MEGG3D is capable of creating data for a porous structure 10 that is suitable for reducing aerodynamic noise, based on information about fluid flow analyzed using computational fluid dynamics, under various conditions at the location where the porous structure 10 is attached (for example, flight speed and altitude of the aircraft 20).

[0030] In MEGG3D, first, to match the shape (outer shape) of the body of the porous structure 10, Pre-data for the porous structure 10, in which the tetrahedral element 2 (see also Figure 2 below) is a constituent element, is generated (center of the upper part of Figure 1).

[0031] The shape of each tetrahedron element 2 in this preliminary data is given randomness, taking into account fluid flow in computational fluid dynamics and the reduction of aerodynamic noise. Each tetrahedron element 2 does not need to be a regular tetrahedron, and is non-uniform and irregular.

[0032] Next, in MEGG3D, the tetrahedral element 2 in the previous data is divided into multiple (four) hexahedral elements 3 (see also Figure 2 below), and data for a porous structure 10 in which the hexahedral elements 3 are constituent elements is generated (upper right of Figure 1).

[0033] The shape of each hexahedral element 3 in this data, like that of the tetrahedral element 2, is given randomness, taking into account fluid flow in computational fluid dynamics and the reduction of aerodynamic noise. Each hexahedral element 3 does not need to be a regular hexahedron, and is non-uniform and irregular.

[0034] Figure 2 shows how a tetrahedron element 2 is divided into a hexahedron element 3 in MEGG3D.

[0035] As shown in Figure 2, in MEGG3D, when a tetrahedron element 2 is divided into multiple (four) hexahedron elements 3, first, for each of the four triangles in the tetrahedron element 2, three first points (see black circles) are determined on the three prism elements 1 that make up the triangle. Based on these first points, each of the three prism elements 1 is divided into two prism elements 1.

[0036] The first point is a point near the midpoint of each prism element 1 in the triangle, but due to the randomness mentioned above, it is not precisely the midpoint. In adjacent triangles, one prism element 1 is common, and one first point is determined for that prism element 1. Therefore, for one tetrahedron element 2, the total number of first points is 6 (4 × 3 / 2).

[0037] Next, for each of the four triangles that make up tetrahedron element 2, one second point (see white circle) inside the triangle is determined. The second point is a point near the center of the triangle, but because of the randomness mentioned above, it is not precisely at the center. For each tetrahedron element 2, there are a total of four second points.

[0038] Next, for each of the four triangles that make up tetrahedron element 2, three prism elements 1 are determined, connecting three first points (see black circles) and one second point (see white circle). These prism elements 1 are then added to the prism elements 1 that make up the tetrahedron. The total number of prism elements 1 added at this time is 12 (4 × 3).

[0039] Next, one third point (see double circle) inside tetrahedron element 2 is determined. This third point is near the center of the tetrahedron, but due to the randomness mentioned above, it is not precisely at the center. Then, four pillar elements 1 are added, connecting the four second points (see white circles) and the one third point.

[0040] In this way, in MEGG3D, one tetrahedron element 2 is divided into four hexahedron elements 3.

[0041] In this specification, unless otherwise specified, the term "column element 1" refers to the column component that constitutes each edge of the hexahedron element 3.

[0042] In the data for the porous structure 10 made of hexahedral elements 3, created with MEGG3D, the coordinate information of the start point 1a and end point 1b of each column element 1 is output as text information to CAD (Computer Aided Design) software (for example, CATIA (Computer graphics Aided Three dimensional Interactive Application): registered trademark) (lower right of Figure 1).

[0043] Furthermore, the coordinate information of the start point 1a and end point 1b of each column element 1 in the CAD software can be output to spreadsheet software (for example, Excel®) and linked. In this case, by updating the coordinate information of the start point 1a and end point 1b in the spreadsheet software, it is possible to partially change the shape of the hexahedron element 3 and partially optimize it by manually adjusting the void ratio.

[0044] Next, in the CAD software, a unification process (union process) is performed on each column element 1 (center of the lower part of Figure 1). In other words, at this point, each column element 1 is simply overlapping, so an unification process is performed to unify each column element 1. This unification process eliminates the overlapping parts of the column element 1 bodies, and in the CAD, valley lines (indicated by black arrows) appear at the intersections of each column element 1. Note that since the unification process is performed on each column element 1 individually, it can be automated using a macro.

[0045] This integration process reduces the size of the STL data ultimately output to the 3D printer and also prevents errors caused by the 3D printer.

[0046] Next, in the CAD software, parts other than the porous structure 10 are added (lower left of Figure 1). In this example, the parts other than the porous structure 10 are shown as the base 11 below the porous structure 10 and the multiple columns 12 connecting the base 11 and the porous structure 10. Note that the porous structure 10 may be provided with mounting bases (not shown) for attaching the porous structure 10 to an object.

[0047] Next, the data for the porous structure 10 generated in the CAD software (data including the porous structure 10, which is composed of hexahedral elements 3, and the other parts 11 and 12) is output as an STL file to the 3D printer. The 3D printer then creates a 3D model of the porous structure 10 (a model including the porous structure 10) based on the input data.

[0048] Figure 3 shows a porous structure 10 produced by a 3D printer. As shown in Figure 3, first, the porous structure 10 is manufactured by removing the lower base 11 and multiple columns 12 from the molded object containing the porous structure 10, which was produced by the 3D printer.

[0049] Figure 3 shows an example where the porous structure 10 is made of resin. Figure 4 is a perspective view showing an example where the porous structure 10 is made of metal (SUS) (column element 1 diameter 0.2 mm). Figure 5 is a top view showing an example where the porous structure 10 is made of metal (SUS) (column element diameter 0.2 mm).

[0050] <Configuration of the porous structure 10> Next, the structure of the porous structure 10 will be described.

[0051] The porous structure 10 according to this technology is manufactured by the manufacturing method described above. Accordingly, the porous structure 10 according to this technology is manufactured by creating data for a porous structure 10 having a structure suitable for reducing aerodynamic noise under corresponding conditions (e.g., the flight speed and altitude of the aircraft 20) based on mesh structure creation software used in computational fluid dynamics, and then creating the porous structure 10 using a 3D printer based on the created data.

[0052] Furthermore, the porous structure 10 is composed of a mesh made up of hexahedral elements 3. Each hexahedral element 3 is composed of multiple (four) hexahedral elements 3, formed by dividing a tetrahedral element 2 into several hexahedral elements 3.

[0053] When tetrahedron element 2 is divided into hexahedron element 3, the following column element 1 is added to the six column elements 1 that make up tetrahedron element 2. Note that the six column elements that make up tetrahedron element 2 are each divided into two column elements 1 by the first point.

[0054] In other words, when tetrahedron element 2 is divided into hexahedron element 3, for each of the four triangles in tetrahedron element 2, three additional pillar elements 1 are added, connecting the three first points of the three pillar elements 1 that make up the triangle (see black circles in Figure 2) to the one second point inside the triangle (see white circle in Figure 2) (a total of 12 pillar elements 1).

[0055] Furthermore, when the tetrahedron element 2 is divided into hexahedron element 3, four additional prism elements 1 are added, connecting the four second points inside the four triangles of the tetrahedron element 2 (see white circles in Figure 2) and the one third point inside the tetrahedron element 2 (see double circle in Figure 2).

[0056] The porous structure 10 can be made of various materials such as resin or metal. The porous structure 10 may be made entirely of the same material, or it may be made partially of different materials.

[0057] Figure 6 shows an example of a porous structure 10.

[0058] In this porous structure 10, the porosity was set to 83%. It is known that a higher porosity results in a greater reduction of aerodynamic noise, and typically the porosity is 80% or higher. Furthermore, for the same volume and the same number of n-hedral elements, a higher value of "n" in the n-hedral elements results in a higher porosity.

[0059] In tetrahedral element 2, the value of "n" is low, making it difficult to increase the porosity (there is a 10% to 20% difference in porosity between tetrahedral element 2 and hexahedral element 3). Furthermore, it is conceivable to construct the porous structure 10 using pentahedral elements, hexahedral elements, octahedral elements, etc., but these have complex shapes, making it difficult to calculate the porous structure 10 containing such polyhedral elements.

[0060] Therefore, in this embodiment, a hexahedral element 3 is adopted. With a hexahedral element 3, a relatively high porosity can be achieved, and it can also be formed by dividing a tetrahedral element 2 into multiple (four) parts, making it easy to manufacture.

[0061] In the example shown in Figure 6, resin (Vitra-413: resin model number by DWS Inc.) was used as the material for the porous structure 10. The outer diameter of the porous structure 10 was 45 mm, the inner diameter was 25 mm, and the thickness was 10 mm. The diameter of the column element 1 constituting the hexahedral element 3 was 0.5 mm, and the target length of the column element 1 was 2 mm. The column 12 formed on the base 11 had a diameter of 0.4 mm.

[0062] Here, it is known that a high reduction in aerodynamic noise is achieved when the number of cells (number of n-hedral elements) in a length of 25 mm (1 inch) is in the range of approximately 11 to 16. Therefore, in this example, the target length of column element 1 is set to 2 mm (≒25.4 mm / 13 cells). As mentioned above, each hexahedral element 3 in the porous structure 10 is random and non-uniform. Therefore, there is a distribution in the lengths of the column elements 1 that constitute the hexahedral element 3.

[0063] Figure 7 shows the distribution of lengths of columnar elements 1 in the hexahedral element 3. In Figure 7, the horizontal axis represents the range of lengths of columnar elements 1, and the vertical axis represents the number of columnar elements 1 with lengths within that range. In this example, the total number of columnar elements 1 in the porous structure 10 was approximately 6000. The average length of columnar elements 1 was 1.97 mm, and the median length was 1.72 mm.

[0064] Figure 7 shows that the lengths of column element 1 are distributed mainly around the target length (2 mm).

[0065] Figure 8 shows how the porous structure 10 looks when attached to the aircraft 20. As shown in Figure 8, the porous structure 10 (for example, made of metal) is attached to the inner surface of the landing gear door 21 of the aircraft 20. When this porous structure 10 is manufactured, first the airflow is analyzed based on conditions such as the flight speed and altitude of the aircraft 20 when the landing gear door 21 is open (during takeoff and landing). Then, MEGG3D calculates a hexahedral element 3 with randomness suitable for reducing aerodynamic noise under those conditions, and the porous structure 10 is manufactured based on this.

[0066] By attaching this porous structure 10 to the inner surface of the landing gear door 21 of the aircraft 20, aerodynamic noise from the landing gear 22 and landing gear door 21 can be reduced.

[0067] In this example, an aircraft 20 was used as an example of an object to which the porous structure 10 is attached, but the object is not limited to an aircraft 20. For example, the object may be an automobile or a railway vehicle. Typically, the object to which the porous structure 10 is attached can be any object to which aerodynamic noise is a problem. Furthermore, the location where the porous structure 10 is attached can also be any location.

[0068] <Effect, etc.> Next, the operation and other aspects of the porous structure 10 according to this embodiment will be described. In this description, a comparative example that can be compared with this embodiment will be described first.

[0069] [Comparative Example 1] In the first comparative example, it is assumed that a commercially available metal product (Celmet (registered trademark: manufactured by Toyama Sumitomo Electric)) is used as the porous structure 10 (see Example 4 in paragraph

[0055] of Patent Document 1 above).

[0070] When this off-the-shelf metal product (Celmet) is used as the porous structure 10, there are problems such as difficulty in handling due to the sharp skeletal structure protruding from the surface. Furthermore, there are problems such as difficulty in attaching the porous structure 10 to the object to which it is attached. In addition, there are problems such as difficulty in the method of attaching the object.

[0071] [Comparative Example 2] Figure 9 shows a second comparative example. In this second comparative example, it is assumed that a lattice structure created by a 3D printer, as proposed by Nippon Additive Manufacturing Co., Ltd. (registered trademark), is used as the porous structure 10.

[0072] As shown in Figure 9, in the second comparative example, a basic grid shape is first created, and by arranging this grid shape three-dimensionally, data for a rectangular prism is created (left side of Figure 9). Next, shape data for an arbitrary object, which represents the final shape of the object, is created (for example, a sphere: center of Figure 9).

[0073] Next, these two sets of data are superimposed on the conversion software. Then, this data is output to a 3D printer, and the 3D printer creates the object 31 (Figure 9, right side).

[0074] When this molded object 31 is used as a porous structure 10, the curved surface portion is missing, resulting in sharp skeletal structures protruding from the surface, which presents problems such as difficulty in handling.

[0075] [Third Comparative Example] Figure 10 shows a third comparative example. In this third comparative example, as with the second comparative example, it is assumed that a lattice structure created by a 3D printer, as proposed by Nippon Additive Manufacturing Co., Ltd., is used as the porous structure 10.

[0076] In the third comparative example, the triangular boundary lines of the STL data are used, and only the boundary lines are fabricated to create the object 32. In the third comparative example, the object 32 is a surface-only structure, and there is a problem that it is not possible to create a structure inside the structure. Furthermore, there is a problem that only triangular grid shapes can be created on the surface.

[0077] [Comparative Example 4] In the fourth comparative example, it is assumed that a lattice structure created using design software for 3D printers is used as a porous structure. In the fourth comparative example, for example, a pre-prepared pattern function is used as the basis, and parameters such as the density and thickness of the target object are controlled, thereby automatically generating the lattice structure in the design software.

[0078] In the fourth comparative example, while it is possible to create a lattice structure that conforms to the desired shape (a three-dimensional shape including curves, etc.), there is a problem in that it is not possible to create a structure suitable for reducing aerodynamic noise.

[0079] [This Circumstance] In this embodiment, the porous structure 10 is created using software for creating mesh structures used in computational fluid dynamics. Data for the porous structure 10 having a structure suitable for reducing aerodynamic noise under corresponding conditions is created, and the structure is then manufactured using a 3D printer based on the created data.

[0080] Therefore, in this embodiment, a porous structure 10 having a structure suitable for reducing aerodynamic noise can be easily created. Furthermore, in this embodiment, the sharp skeletal structure does not protrude from the surface, making it easy to handle.

[0081] Furthermore, in this embodiment, since the porous structure 10 is created by a 3D printer, the porous structure 10 can be easily created to match the shape of the object to which it will be attached. This allows the porous structure 10 to be easily attached to the object even if the object to which it will be attached has a complex shape. In addition, for example, by performing 3D printing with the attachment base embedded in the porous structure 10, attachment to the object can be made even easier.

[0082] Furthermore, the porosity of the porous structure 10 can be partially adjusted, in which case the effect of reducing aerodynamic noise can be optimized.

[0083] Furthermore, the porous structure 10 according to this embodiment is composed of a mesh in which hexahedral elements 3 are constituent elements. By using hexahedral elements 3 as constituent elements in this way, the porosity can be set to a high value suitable for reducing aerodynamic noise.

[0084] Furthermore, in the porous structure 10 according to this embodiment, the tetrahedral element 2 is divided into a plurality of hexahedral elements 3. By dividing the tetrahedral element 2 into a plurality of hexahedral elements 3 in this way, the porous structure 10 made up of hexahedral elements 3 can be easily created.

[0085] Furthermore, the porous structure 10 according to this embodiment includes three columnar elements 1 for each of the four triangles in the tetrahedron element 2, connecting the three first points of the three columnar elements 1 constituting the triangle with one second point inside the triangle (a total of 12 columnar elements 1). In addition, the porous structure 10 according to this embodiment includes four columnar elements 1 connecting the four second points inside the four triangles in the tetrahedron element 2 with one third point inside the tetrahedron element 2.

[0086] This makes it possible to obtain a porous structure 10 that has been appropriately transformed from a structure containing tetrahedral elements 2 to a structure containing hexahedral elements 3. [Explanation of Symbols]

[0087] 1… Pillar element 2...Tetrahedron elements 3...Hexahedral elements 10...Porous structure

Claims

1. A porous structure for reducing aerodynamic noise having a void structure formed by column elements, The porous structure is a mesh structure in which the column elements are joined together, and is composed of a mesh in which hexahedral elements are constituent elements. The lengths of the columnar elements constituting the hexahedron are distributed such that one tetrahedron is divided into multiple non-uniform hexahedrons. A porous structure for reducing aerodynamic noise.

2. A porous structure for reducing aerodynamic noise according to Claim 1, The porous structure includes a plurality of non-uniform tetrahedral elements. A porous structure for reducing aerodynamic noise.

3. A porous structure for reducing aerodynamic noise according to claim 1, When the tetrahedron element is divided into a plurality of hexahedron elements, for each of the four triangles in the tetrahedron element, three additional prism elements are added, connecting the three first points in the three prism elements constituting the triangle, which are shifted from the midpoint in the longitudinal direction of the prism elements, and the second point inside the triangle, which is shifted from the center of the triangle. A porous structure for reducing aerodynamic noise.

4. A porous structure for reducing aerodynamic noise according to claim 3, When the tetrahedron element is divided into a plurality of hexahedron elements, four additional prism elements are added, connecting the four second points inside the four triangles of the tetrahedron element with a third point inside the tetrahedron element that is shifted from the center of the tetrahedron element. A porous structure for reducing aerodynamic noise.

5. A porous structure for reducing aerodynamic noise according to claim 1, The porous structure is created to match the shape of the object to which the porous structure is attached. A porous structure for reducing aerodynamic noise.

6. A porous structure for reducing aerodynamic noise according to claim 1, The porous structure includes a mounting base for attaching the porous structure to an object. A porous structure for reducing aerodynamic noise.

7. Based on software for creating mesh structures used in computational fluid dynamics, we created data for a porous structure with a void structure formed by column elements, suitable for reducing aerodynamic noise under corresponding conditions. A porous structure is created using a 3D printer based on the data that has been generated. A method for manufacturing a porous structure for reducing aerodynamic noise, The porous structure is a mesh structure in which the column elements are joined together, and is composed of a mesh in which hexahedral elements are constituent elements. The lengths of the columnar elements constituting the hexahedron are distributed such that one tetrahedron is divided into multiple non-uniform hexahedrons. A method for manufacturing a porous structure for reducing aerodynamic noise.

8. A method for manufacturing a porous structure for reducing aerodynamic noise according to claim 7, In the aforementioned software, preliminary data for a porous structure whose constituent elements are tetrahedral elements is generated, and the tetrahedral elements in the preliminary data are divided into a plurality of hexahedral elements to generate data for the porous structure whose constituent elements are hexahedral elements. A method for manufacturing a porous structure for reducing aerodynamic noise.

9. A method for manufacturing a porous structure for reducing aerodynamic noise according to claim 8, In the software described above, when the tetrahedron element is divided into a plurality of hexahedron elements, for each of the four triangles in the tetrahedron element, three additional prism elements are added, connecting the three first points in the three prism elements constituting the triangle, which are shifted from the midpoint in the longitudinal direction of the prism elements, and the second point inside the triangle, which is shifted from the center of the triangle. A method for manufacturing a porous structure for reducing aerodynamic noise.

10. A method for manufacturing a porous structure for reducing aerodynamic noise according to claim 9, In the software described above, when the tetrahedron element is divided into a plurality of hexahedron elements, four additional columnar elements are added, connecting the four second points inside the four triangles of the tetrahedron element with a third point inside the tetrahedron element that is shifted from the center of the tetrahedron element. A method for manufacturing a porous structure for reducing aerodynamic noise.

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