JP6281270B2 - Method and program for creating simulation model - Google Patents

Description

  The present invention relates to a simulation model creation method for simulating fluid flow in a space surrounding a tire, and a program for executing the creation method.

  Conventionally, simulation calculation of the flow of fluid such as air around a structure using a computer has been performed. In this simulation calculation, in order to reproduce the fluid flow, a model in which the fluid space is divided into a number of regions, that is, a meshed model is created. Currently, a simulation model divided into meshes is also used in a simulation calculation for reducing the aerodynamic resistance of a vehicle including a tire.

  For example, a simulation method for efficiently developing a golf club by using a golf club as a structure and evaluating the aerodynamic characteristics of the golf club head without performing a test evaluation using a real model has been proposed (Patent Document). 1).

In the simulation method, the airflow virtual region is divided into a large number of grid sections so that the volume of the grid sections gradually increases in a direction away from the ball surface of the golf ball model.
In addition, the golf club head model has a plurality of polygonal surfaces such as triangles and rectangles, or substantially polygonal surfaces such as substantially triangles and rectangles, and a golf club having each of these surface regions as one surface. Set a grid section adjacent to the model surface of the head. The lattice section adjacent to the model surface of the golf club head is set to a substantially polygonal column shape such as a substantially quadrangular prism shape or a substantially polygonal pyramid shape. The remainder of the airflow virtual region is partitioned in a lattice shape so that the volume of the lattice partition gradually increases in the direction away from the golf club head from the lattice partition adjacent to the model surface of the golf club head. Compartment with lattice section.

In addition, a study in which the relationship between the main groove of the tire and the aerodynamic characteristics is analyzed using a simulation model is also known (Non-Patent Document 1).
In this research, a simulation model in which the fluid space around the tire is divided into meshes is used.

JP 2012-135344 A Kimura et al., "Numerical study on the effect of longitudinal grooves on the flow field around the tire", Proceedings of the Visualization Information Symposium, p. 12-006, 2013

  However, when the simulation model described above is used in a simulation method for aerodynamic resistance of a vehicle including a tire, various tire models having different shapes are created, particularly in order to examine the effect of the tire shape on the aerodynamic resistance. Each time a tire model is created, a simulation model is created by dividing the mesh as a space around the tire model. Since such a simulation model includes a very large number of mesh divisions, it takes time for mesh division. Therefore, the time required for aerodynamic resistance simulation using various tire models becomes long.

  Therefore, the present invention provides a simulation model creation method capable of reducing the time required to create a simulation model and a program for executing the creation method when simulating a fluid flow in a space surrounding a tire. For the purpose.

One aspect of the present invention is a method for creating a simulation model for simulating fluid flow in a space surrounding a tire. The creation method is
(1) A first model space region that reproduces a first space region that borders at least a part of the shape of the tire, and a second space region that is located around the first space region. Meshing the two model space regions separately;
(2) defining a relationship for interpolating the physical quantity of the fluid between the first mesh created in the first model space region and the second mesh created in the second model space region; , including the.
The first model space region and the second model space region are separated from each other, and the dimension of the separation distance between the first model space region and the second model space region is the first model space region. Smaller than the minimum mesh size dimension of the mesh,
In the step of determining a relationship for interpolating the physical quantity of the fluid, the first mesh is applied when the first mesh gives the second mesh and the second mesh gives the first mesh a physical quantity. In the second mesh, when there are a plurality of physical quantity-giving meshes B facing the physical quantity receiving mesh A, the size of the boundary surface portion of the mesh B facing the mesh A The relationship is determined so that the mesh A is given a weighted average value of the physical quantities of the mesh B according to the ratio.

  At this time, it is preferable that the average size of the first mesh is smaller than the average size of the second mesh.

The first mesh is in contact with a tire model that models the tire,
When the width dimension of the tire model in the tire width direction of the tire model is St [mm] and the diameter dimension of the tire model is Dt [mm], the tire width direction of the first model space region is the tire width direction. The width dimension S [mm] is a dimension larger than 0.1 times and smaller than three times the width dimension St, and the maximum value of the dimension along the tire radial direction of the first space region is It is preferable that the dimension is larger than 0.3 times the diameter dimension Dt and smaller than twice.

  It is preferable that the first model space region includes a model space region that reproduces a space in contact with a sidewall of the tire.

  It is also preferable that the first model space region includes a model space region that reproduces a space in contact with the tread pattern of the tire.

  In order to reproduce the rotation of the tire around the tire rotation axis, the first mesh is preferably a mesh that rotates around the tire rotation axis.

Yet another embodiment of the present invention is a computer-executable program that causes a computer to execute a simulation model creation method for simulating fluid flow in a space surrounding a tire. The program is
(3) A first model space region that reproduces a first space region that borders at least a part of the shape of the tire, and a second space region that is located around the first space region. A procedure for causing a computer to perform the process of dividing the model space area of the two meshes separately;
(4) A relationship for interpolating the physical quantity of the fluid between the first mesh created in the first model space region and the second mesh created in the second model space region is determined in the computer. including a procedure for, the.
The first model space region and the second model space region are separated from each other, and the dimension of the separation distance between the first model space region and the second model space region is the first model space region. Smaller than the minimum mesh size dimension of the mesh,
In the step of causing the computer to determine a relationship for interpolating the physical quantity of the fluid, when the first mesh gives a physical quantity to the second mesh and the second mesh gives the physical quantity to the first mesh, the first mesh In the case where there are a plurality of meshes B on the physical quantity-given side facing the mesh A on the physical quantity receiving side among the one mesh and the second mesh, the boundary surface of the mesh B facing the mesh A The relationship is determined so that the mesh A is given a weighted average value of the physical quantities of the mesh B according to the ratio of the size of the parts.

  According to the simulation model creation method and program of the above-described aspect, the time required to create the simulation model can be shortened.

It is a block block diagram of the model creation apparatus which performs the creation method of the simulation model of this embodiment. It is a figure explaining the flow of the preparation method of the simulation model of this embodiment. It is a figure which shows an example of the 1st mesh in the 1st model space area | region and the 2nd model space area which were created with the creation method of the simulation model of this embodiment, and a 2nd mesh. It is a figure which shows an example of the simulation model created with the creation method of the simulation model of this embodiment. (A), (b) is a figure explaining the example of the relationship of the interpolation between the 1st model space area | region created with the creation method of the simulation model of this embodiment, and a 2nd model space area | region. It is a figure which shows an example of the space area and vehicle model which are used with the preparation method of the simulation model of this embodiment.

  Hereinafter, a simulation model creation method and program according to the present embodiment will be described in detail with reference to the drawings. Note that the simulation model obtained by dividing the space region used in this embodiment into a mesh is a simulation model that can be applied to simulation calculations of the finite element method, the finite difference method, the finite volume method, the finite mesh method, and the lattice Boltzmann method.

FIG. 1 is a block configuration diagram of a model creation apparatus 10 that executes the simulation model creation method of the present embodiment. The model creation device 10 is configured by a computer having a CPU 12, a memory 14, a ROM 16, and an input / output unit 18. The ROM 16 stores a program for executing the simulation model creation method according to the present embodiment, and is called and executed by an instruction from the CPU 12 to execute an area setting unit 20, a mesh dividing unit 22, and an interpolation relation setting unit 24. And the control unit 26 are formed.
The area setting unit 20 sets a first model space area and a second model space area in accordance with an instruction from the operator.
The mesh division unit 22 meshes the first model space region and the second model space region separately.
The interpolation relationship setting unit 24 sets a relationship for interpolating the physical quantity of the fluid between the first mesh created in the first model space region and the second mesh created in the second model space region. . This setting is performed in accordance with an operator instruction.
The control unit 26 controls the operation of the region setting unit 20, the mesh division unit 22, and the interpolation relation setting unit 24, or makes a determination.
The input / output unit 18 is connected to an input operation device 27 such as a mouse / keyboard, a display 28, and a printer 30.
The memory 14 stores the processing results obtained by the region setting unit 20, the mesh division unit 22, and the interpolation relation setting unit 24, and setting conditions before processing.

FIG. 2 is a diagram for explaining the flow of a simulation model creation method performed by the model creation apparatus 10. The simulation model of this embodiment is a model for simulating the flow of fluid in the space surrounding the tire.
First, the region setting unit 20 sets the tire shape (step S10). The shape of the tire is a three-dimensional shape, for example, a shape that faithfully reproduces the tread pattern, the irregularities on the surface of the sidewall, and the sectional shape of the sidewall. The shape of the tire is stored in the memory 14 and is called from the memory 14. Alternatively, the shape can be set by the input operation device 27.

Next, the mesh division unit 22 includes a first model space region 30 that reproduces a first space region that has at least a part of the shape of the tire as a boundary in a space surrounding the tire, and around the first space region. A second model space region 32 that reproduces the second space region positioned at is created and meshed separately (step S20). The first model space region 30 and the second model space region 32 that are divided into meshes are stored in the memory 14.
Note that the first space region does not include a tire. Therefore, the first model space region 30 is a space region in which the shape of the tire is reproduced by the boundary surface. The “at least part of the tire” described above includes a tread portion having a tread pattern or a side portion, and may include the entire tire. Note that in the first mesh created by the first model space region 30, the mesh lattice points are located on the surface of the tire shape, or slightly outside the tire surface, and these linear created by two grid points close to the shape of the tire among the lattice points or a part of the plane created Ri by the at least three grid points may be through the inner shape of the tire. In mesh division, a three-dimensional space region is finely divided by elements such as a tetrahedron, a pentahedron, or a hexahedron. The mesh dividing method is not particularly limited, and a known mesh dividing method is used.
FIG. 3 is a diagram illustrating an example of the first mesh and the second mesh in the first model space region 30 and the second model space region 32 created separately. The second model space region 32 has a recess 38 that roughly corresponds to the size and outer peripheral shape of the first model space region 30.

Next, when the interpolation relationship setting unit 24 incorporates the first model space region 30 into the second model space region 32 to form one space region, the first model space region 30 and the second model space Interpolation relations are set so that physical quantities are appropriately transferred between mesh areas adjacent to the area 32 (step S30). Between each of the mesh regions having the boundary surfaces facing each other in the first model space region 30 or the second model space region 32, between the mesh region of the second model space region 32 or the first model space region 30 Thus, the physical quantity interpolation relationship for transferring the physical quantity is defined. When performing the simulation calculation, it is necessary for the physical quantity to be continuously connected at the connecting portion between the first model space region 30 and the second model space region 32 in order to obtain an appropriate simulation result. For this reason, the relationship which interpolates the physical quantity of the fluid between the 1st mesh created in the 1st model space area | region 30 and the 2nd mesh created in the 2nd model space area | region 32 is defined. Here, the physical quantity of the fluid includes speed, pressure, density, or temperature. As for the physical quantity of the fluid, the average physical quantity in the mesh area adjacent to each other and the physical quantity at the center of gravity of the mesh area are transferred between the mesh areas adjacent to each other in the first model space area 30 and the second model space area 32.
Thereby, the interpolation relation setting unit 24 creates a simulation model having one model space area in which the separately created first model space area 30 is incorporated into the second model space area 32 (step S40). FIG. 4 is a diagram illustrating an example of one created simulation model.

FIGS. 5A and 5B are diagrams illustrating an example of an interpolation relationship between the first model space region 30 and the second model space region 32. FIG.
In the example shown in FIG. 5A, the first mesh area 34 and the second mesh area 36 facing the boundary between the first model space area 30 and the second model space area 32 are interpolated. This is an area. The sizes of the mesh regions facing each other are the same size, and the boundary surfaces of the mesh regions are opposed to each other. At this time, the interpolation relationship setting unit 24 extracts the second mesh region 36 facing the closest to the first mesh region 34, and the first mesh region 36 is extracted to the second mesh region 36. The physical quantity at 34 is given. Alternatively, the opposing second mesh region 36 located closest to the first mesh region 34 is extracted, and a physical quantity in the second mesh region 36 is given to the first mesh region 34. That is, the physical quantities in the first mesh region 34 and the second mesh region 36 are the same.
Here, the physical quantity of the mesh area is exemplified by an average physical quantity in the mesh area or a physical quantity at the center of gravity of the mesh area.

Also in the example shown in FIG. 5B, the first mesh area 34 and the second mesh area 36 facing the boundary between the first model space area 30 and the second model space area 32 are interpolated. This is an area. In the example shown in FIG. 5 (b), the sizes of the mesh regions facing each other are different, and the opposing boundary surfaces of the mesh regions are displaced from each other in the circumferential direction of the tire shape. In the example shown in FIG. 5 (b), the first mesh region 34a and the second mesh region 34b are adjacent to each other in the circumferential direction, the second mesh region 36a and the second mesh region 36b adjacent to each other in the circumferential direction doing. Furthermore, the size along the circumferential direction of the tire shape at the boundary surface of the first mesh regions 34a and 34b is larger than the size along the circumferential direction of the tire shape at the boundary surface of the second mesh regions 36a and 36b. Big. In such a case, since all the boundary surfaces of the second mesh region 36a are opposed to the boundary surface of the first mesh region 34a, the physical quantity in the first mesh region 34a is included in the second mesh region 36a. give. Since the boundary surface of the second mesh region 36b faces the boundary surface of the first mesh region 34b across the boundary surface of the first mesh region 34b, the physical quantity in the first mesh region 34a The average value of the physical quantities in the mesh region 34b is given. In this case, it is preferable to use a weighted average value described below as the average value. The weighting coefficient used for the weighted average value is the size of the boundary surface portion of the first mesh region 34a facing the boundary surface of the second mesh region 36b and the first surface facing the boundary surface of the second mesh region 36b. This coefficient is determined according to the ratio of the size of the boundary surface portion of the mesh area 34b, and the weighting coefficient increases as the ratio increases.
Similarly, when a physical quantity is given to the first mesh area 34a, an average value of the physical quantity in the second mesh area 36a and the physical quantity in the second mesh area 36b is given. The average value is preferably the above-described weighted average value.
In addition, for the interpolation of the physical quantity between the first model space area 30 and the second model space area 32, linear extrapolation interpolation may be applied to the physical quantity using the mesh area position information or the grid point position information. Alternatively, well-known parametric spatial interpolation can be applied. Parametric spatial interpolation is described in, for example, Japanese Patent No. 4548005 (paragraphs 0026 to 0031). Parametric spatial interpolation is to try to complement the physical quantity by defining the mesh area including the point to interpolate the physical quantity as a shape converted from a unit mesh area such as a rectangular shape using a shape function. In this process, the position information of the corresponding point in the shape of the unit mesh area corresponding to the point in the mesh area to be obtained is obtained, and the physical quantity is complemented using this position information.

In this way, by defining the physical quantity interpolation relationship, one simulation model as shown in FIG. 4 is created. In such a simulation model, the fluid flow is reproduced.
Furthermore, when making another simulation model by changing the shape of the tire, first, the region setting unit 20 sets the changed shape of the tire (step S50).
The changed tire shape may be called from the memory 14 or may be set by an input using an input operation device 27 such as a mouse / keyboard.

  Next, the mesh division unit 22 includes a first model space region 30 that reproduces a first space region that has at least a part of the shape of the tire as a boundary in a space surrounding the tire having the set shape of the tire. Set again and divide the mesh. The outer circumference of the mesh-divided first model space area 30 corresponds to the size of the concave portion 38 of the second model space area 32 so as to be incorporated into the second model space area 32 mesh-divided in step S20. doing. In step S60, the second model space region 32 is not newly created. The first model space region 30 created in step S50 is created in accordance with the changed tire shape, and the outer periphery corresponds to the size of the recess 38 of the second model space region 32. That is, since the mesh dividing unit 22 meshes only the first model space region 30, the model creation time can be greatly reduced. As the second model space region 32 divided by mesh, the one created in step S20 is used.

Next, the interpolating relationship setting unit 24 creates the first model space area 30 divided in mesh created in step S60 and the second model divided in mesh created in step S20 and stored in the memory 14. An interpolating relationship between physical quantities is set using the space region 32 (step S70). The setting of the interpolation relationship is performed by the same method as the setting of the physical quantity interpolation relationship in step S30. For this reason, the description of the interpolation relation setting in step S70 is omitted.
By setting the physical quantity interpolation relationship for each mesh region located on the boundary surface, the interpolation relationship setting unit 24 creates a simulation model in which the first model space region 11 is incorporated into the second model space region 32. (Step S80). In this way, a simulation model that reproduces the space around the tire whose shape has been changed is obtained.

  Furthermore, the control unit 26 determines whether or not to create a simulation model that reproduces the space around the tire whose shape is changed (step S). The control unit 26 proceeds to a step of repeating steps S60 to S80 or performs a calculation using a simulation model (step S100) according to an input instruction from the input operation device 27 by the operator. When performing the simulation calculation, for example, the control unit 26 calls and activates software stored in the ROM 16 and starts up a software module having a function of performing the simulation calculation. This software module performs a simulation calculation using the plurality of simulation models created in step S40 and step S80. The simulation calculation is performed using, for example, a finite element method, a finite difference method, a finite volume method, a finite mesh method, or a lattice Boltzmann method.

  As described above, when the simulation model of the space region is created by changing the shape of the tire, the second model space region 32 previously created and stored in the memory 14 is used every time the shape of the tire is changed. Therefore, only the first model space region 30 needs to be mesh-divided. Therefore, the time required for creating the simulation model can be shortened.

  The average size of the first mesh in the first model space region 30 is smaller than the average size of the second mesh in the second model space region 32, so that the fluid around the tire is accurately reproduced. In terms, it is preferable. Here, the average size includes the average volume of the mesh region, the average element length of the mesh region, or the average length of the sum of the element lengths of each mesh region. The “average element length” is an average of the lengths of line segments forming each mesh region in all mesh regions of the first model space region 30 or the second model space region 32. “The average length of the sum of the element lengths of each mesh area” means the total length of the line segments that make up each mesh area, the total mesh of the first model space area 30 or the second model space area 32 It is averaged over the area.

  The first mesh in the first model space region 30 is in contact with the tire model that models the tire, and the tire model width dimension in the tire width direction of the tire model is St [mm]. The diameter dimension in the radial direction is Dt [mm]. At this time, the width dimension S [mm] in the tire width direction of the first model space region 30 is a dimension larger than 0.1 times and smaller than three times the width dimension St of the tire model, and the first model. The maximum value in the tire radial direction of the space region 30 is a size that is larger than 0.3 times the diameter size Dt and smaller than twice, so that the mesh model of the first model space region 30 is efficiently divided and the simulation model This is preferable in terms of shortening the creation time. Here, the tire model is not a mesh model that can be calculated by simulation, but a rigid body model, and demarcates the boundary of the first model space region 30. Therefore, at the time of simulation calculation, boundary conditions and the like are set on the boundary surface of the first model space region 30 that defines the rigid body model.

  The first model space region 30 and the second model space region 32 may partially overlap or may be separated from each other. However, when separated from each other, the dimension of the separation distance between the first model space area 30 and the second model space area 32 is larger than the minimum mesh size of the first mesh in the first model space area 30. A small value is preferable in terms of ensuring the accuracy of calculation results in simulation calculations, and is preferable in terms of maintaining the accuracy of physical quantity interpolation. Here, the size of the minimum mesh means, for example, the minimum length among the average lengths of the line segments forming each mesh region. The separation distance between the first model space region 30 and the second model space region 32 is a distance D in the drawing in the example shown in FIG.

The first model space region 30 can include, for example, a model space region that reproduces a space in contact with a tire sidewall. When extracting the shape of a tire having excellent aerodynamic resistance by variously changing the shape of the surface unevenness of the sidewall of the tire, the effect is great in that the time for creating a simulation model can be shortened.
The first model space region 30 can include, for example, a model space region that reproduces a space in contact with the tire tread pattern. When extracting tires with excellent aerodynamic resistance by changing the tread pattern and tread profile of the tires, the effect of reducing the time required to create a simulation model is significant. In particular, the mesh region in the vicinity of the tread pattern is subjected to complicated mesh division in terms of accurately reproducing the shape of the tread pattern. For this reason, when the tread pattern is variously changed, only the first model space region 30 needs to be finely divided into meshes, so that the simulation model creation time can be greatly shortened.
Here, the shape of the tire referred to when creating the first model space region 30 can be obtained from the tire design drawing or CAD information. It can also be obtained from a part of the outer shape of the tire calculated by dynamic or static deformation analysis of the tire using a finite element method or the like. By using a part of the outer shape of the tire calculated by dynamic or static deformation analysis of the tire, it is possible to take into account the deformation of the tire when the tire is mounted on an automobile and grounded. There is an effect that the accuracy of simulation is improved as compared with the case of using CAD information. In addition, the deformed shape of the tire when the tire is mounted on the vehicle and grounded is obtained from the result calculated by the dynamic or static deformation analysis of the tire using the finite element method or the like, and the vehicle such as the vehicle. The deformed shape of the actual tire attached to the tire can also be obtained by measuring with a laser shape measuring device or the like.

  Furthermore, in order to reproduce the rotation of the tire around the tire rotation axis, the first mesh in the first model space region 30 can be a mesh that rotates around the tire rotation axis. By making the first mesh in the first model space region 30 rotatable, the simulation calculation result can be made more accurate. In this case, between the rotating first mesh and the non-rotating mesh in the second model space area 32, the physical quantity is transferred by setting the above-described physical quantity interpolation relationship. That is, during the simulation calculation, the first mesh rotates, but it rotates every moment while ticking the time step. Therefore, the physical quantity is received using the method shown in FIGS. 3A and 3B for each time step. The mesh area to be transferred is searched, and the above-described physical quantity is transferred to and from the searched mesh area.

The method for creating a simulation model for simulating the flow of fluid in the space surrounding the tire described above is executed by calling and starting a program stored in the ROM 16. Such programs are
A first model space region 30 that reproduces at least a first space region bounded by the shape of a part of the tire, and a second model that reproduces a second space region located around the first space region A procedure for causing the computer to perform a process of dividing the space region 32 into meshes separately;
A procedure for causing a computer to determine a relationship for interpolating a physical quantity of fluid between a first mesh created in the first model space region 30 and a second mesh created in the second model space region 32; Including.
Such a program can be obtained through a telecommunication line, or can be obtained in a form stored in a ROM or a recording medium.

  As described above, in the present embodiment, the first model space region 30 that reproduces the first space region having at least a part of the shape of the tire as a boundary, and the second model space that is located around the first space region. The second model space region 32 that reproduces the space region is separately divided into meshes, and the first mesh created in the first model space region 30 and the second mesh created in the second model space region 32 are divided. The relationship for interpolating the physical quantity of the fluid between the meshes is defined. Therefore, it can be created as one simulation model as shown in FIG. When the tire shape is changed variously, the first model space region 30 only needs to be recreated, so that it is not necessary to recreate the entire simulation model as shown in FIG. 4, and the simulation model creation time is shortened. Can do.

  The above-described embodiment creates a simulation model including a model space region (first model space region, second model space region) that reproduces the first and second space regions filled with fluid around the tire. However, it is also possible to create a model space region that reproduces a space in which a fluid flows around a vehicle equipped with tires as a simulation model. FIG. 6 is a diagram illustrating an example of a space area and a vehicle model used in the creation method of the present embodiment. When the vehicle model 40, which is a rigid model that reproduces the shape of the vehicle including the tire, is arranged in the model space region 42 and the shape of the tire model mounted on the vehicle model 40 is changed, the model is compared with the tire model. The space area 42 is extremely large. For this reason, it takes a lot of time to repeat the mesh division of the model space region 42 every time the shape of the tire is changed. Therefore, as described in the present embodiment, the first model space region 30 that reproduces the first space region having at least a part of the shape of the tire as a boundary is mesh-divided, and the mesh-divided first model A simulation model can be created in a short time by incorporating the space region 30 into the already created mesh-divided second model space region 32 surrounding the first model space region 30. The model space area 42 is an area including the first model space area 30 and the second model space area 32.

(Experimental example)
The size of the model space area 42 shown in FIG. 6 is 26 m long × 26 m wide × 11 m high. A vehicle model 40 having a size equivalent to an actual vehicle is arranged at the center of this area, and air is passed from one end of the model space area A simulation model for simulating the air flow around the vehicle model 42 was created. The total number of mesh points of the mesh of the simulation model is about 6 million. At this time, according to the conventional method of creating a simulation model by dividing the entire model space region 42 at a time (conventional method) and the first model space region 30 and the first model space according to the flow shown in FIG. The method of this embodiment in which the two model space regions 32 are separately created was performed.
The simulation model creation time required until step S40 of the present embodiment is equivalent to the creation time of the conventional method, but the simulation model creation time between steps S50 to S80 is compared with the creation time of the conventional method. It was 1/5. That is, the method of the present embodiment can reduce the creation time by not dividing the second model space region 32 into meshes. From this, the effect of this embodiment is clear.

  Although the simulation model creation method and program of the present invention have been described in detail above, the present invention is not limited to the above-described embodiment, and various improvements and modifications may be made without departing from the spirit of the present invention. Of course.

10 Model creation device 12 CPU
14 Memory 16 ROM
18 Input / output unit 20 Region setting unit 22 Mesh division unit 24 Interpolation relation setting unit 26 Control unit 27 Input operation device 30 First model space region 32 Second model space region 34, 34a, 34b First mesh region 36, 36a, 36b Second mesh area 38 Recess 40 Vehicle model 42 Model space area

Claims (7)

A method of creating a simulation model for simulating fluid flow in a space surrounding a tire,
(1) A first model space region that reproduces a first space region that borders at least a part of the shape of the tire, and a second space region that is located around the first space region. Meshing the two model space regions separately;
(2) defining a relationship for interpolating the physical quantity of the fluid between the first mesh created in the first model space region and the second mesh created in the second model space region; It includes,
The first model space region and the second model space region are separated from each other, and the dimension of the separation distance between the first model space region and the second model space region is the first model space region. Smaller than the minimum mesh size dimension of the mesh,
In the step of determining a relationship for interpolating the physical quantity of the fluid, the first mesh is applied when the first mesh gives the second mesh and the second mesh gives the first mesh a physical quantity. In the second mesh, when there are a plurality of physical quantity-giving meshes B facing the physical quantity receiving mesh A, the size of the boundary surface portion of the mesh B facing the mesh A A method for creating a simulation model , wherein the relationship is determined so that a value obtained by weighted averaging of physical quantities of the mesh B is given to the mesh A in accordance with the ratio .   The simulation model creation method according to claim 1, wherein an average size of the first mesh is smaller than an average size of the second mesh. The first mesh is in contact with a tire model that models the tire;
When the width dimension of the tire model in the tire width direction of the tire model is St [mm] and the diameter dimension of the tire model is Dt [mm], the tire width direction of the first model space region is the tire width direction. The width dimension S [mm] is a dimension larger than 0.1 times and smaller than three times the width dimension St, and the maximum value of the dimension along the tire radial direction of the first space region is The method for creating a simulation model according to claim 1 or 2, wherein the size is larger than 0.3 times and smaller than twice the diameter dimension Dt. The first model space region comprising said model space area that reproduces the sidewall in contact with the space of the tire, how to create a simulation model according to any one of claims 1-3. The simulation model creation method according to any one of claims 1 to 4 , wherein the first model space region includes a model space region that reproduces a space in contact with a tread pattern of the tire. For the tire to reproduce that rotates about the tire rotation axis, the first mesh is a mesh which rotates around the tire rotational axis, according to any one of claims 1 to 5 How to create a simulation model. A computer-executable program for causing a computer to execute a method of creating a simulation model for simulating a fluid flow in a space surrounding a tire,
(3) A first model space region that reproduces a first space region that borders at least a part of the shape of the tire, and a second space region that is located around the first space region. A procedure for causing a computer to perform the process of dividing the model space area of the two meshes separately;
(4) A relationship for interpolating the physical quantity of the fluid between the first mesh created in the first model space region and the second mesh created in the second model space region is determined in the computer. includes a procedure for, the,
The first model space region and the second model space region are separated from each other, and the dimension of the separation distance between the first model space region and the second model space region is the first model space region. Smaller than the minimum mesh size dimension of the mesh,
In the step of causing the computer to determine a relationship for interpolating the physical quantity of the fluid, when the first mesh gives a physical quantity to the second mesh and the second mesh gives the physical quantity to the first mesh, the first mesh In the case where there are a plurality of meshes B on the physical quantity-given side facing the mesh A on the physical quantity receiving side among the one mesh and the second mesh, the boundary surface of the mesh B facing the mesh A A program characterized in that the relationship is determined so that a value obtained by weighted averaging of physical quantities of the mesh B is given to the mesh A according to a ratio of the sizes of the parts .

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