Fluid Simulation Method

Abstract

To provide a fluid simulation method capable of calculating a flow state of a fluid in consideration of a slip velocity that varies according to a proportion of a fluid material in the vicinity of a wall surface.SOLUTION: A simulation method for calculating a state in which a fluid containing multiple types of fluid materials is flowing in a chamber by using a computer includes the steps of: inputting a chamber model having a wall surface; defining a space model in which an internal space surrounded with the wall surface of the chamber model is modeled with a finite number of elements; defining a fluid model including multiple types of fluid material models in the space model; and performing flow calculation of the fluid model. The step of performing flow calculation includes steps of calculating a volume fraction of the multiple types of fluid material models for the fluid model in contact with the wall surface S52; and calculating a slip velocity with respect to the wall surface of the fluid model in contact with the wall surface based on the volume fraction S53.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a fluid simulation method. [Background technology]

[0002] Patent Document 1 below describes a fluid simulation method that uses a computer to calculate the state of a fluid in a chamber having a wall. This method first involves the steps of setting up a chamber model in which the chamber is modeled using a finite number of elements, and then setting up a material model in which the fluid is modeled.

[0003] Next, a step is performed in which the material model is placed in the chamber model and a flow calculation is performed based on predetermined conditions. In this flow calculation, a linear slip velocity, which is a velocity parallel to the contact surface of the material model, is defined at the contact surface where the material model and the wall surface of the chamber model come into contact. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5564074 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a fluid contains multiple types of fluid material, the slip velocity of the fluid relative to the wall surface is thought to change depending on the proportion of fluid material present near the wall surface, etc., but the technology of Patent Document 1 above was unable to calculate the flow state taking such changes into account.

[0006] The present disclosure has been devised in consideration of the above-described circumstances, and its main purpose is to provide a fluid simulation method capable of calculating the flow state of a fluid, taking into account the slip velocity that changes depending on the proportion of fluid material near the wall surface. [Means for solving the problem]

[0007] The present disclosure is a simulation method for using a computer to calculate the state of a fluid containing multiple types of fluid materials flowing within a chamber, the fluid simulation method including the steps of: modeling the chamber and inputting a chamber model having wall surfaces into the computer; defining a spatial model in which the internal space surrounded by the wall surfaces of the chamber model is modeled with a finite number of elements; defining a fluid model in the spatial model including multiple types of fluid material models in which the multiple types of fluid materials are modeled; and performing a flow calculation of the fluid model by the computer, wherein the step of performing the flow calculation includes the steps of calculating the volume fraction of the multiple types of fluid material models for the fluid model in contact with the wall surfaces; and calculating the slip velocity of the fluid model in contact with the wall surfaces relative to the wall surfaces based on the volume fraction. [Effects of the Invention]

[0008] By employing the above steps, the fluid simulation method of the present disclosure makes it possible to calculate the flow state of a fluid by taking into account the slip velocity that changes depending on the proportion of fluid material near the wall surface. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing a computer for executing the fluid simulation method of the present embodiment. [Figure 2] FIG. 2 is a perspective view showing a fluid flowing in a chamber. [Figure 3] 10 is a flowchart showing a processing procedure of a fluid simulation according to the present embodiment. [Figure 4] 1A and 1B are conceptual diagrams showing a chamber model and a space model of the present embodiment. [Figure 5] FIG. 1 is a partial cross-sectional view of the main chamber model. [Figure 6] 10 is a flowchart showing the processing procedure of a flow calculation step in this embodiment. [Figure 7] FIG. 10 is a contour diagram showing the flow velocity of a fluid material model according to an embodiment. [Figure 8] FIG. 10 is a contour diagram showing the flow velocity of a fluid material model of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. It should be understood that the drawings include exaggerated representations and representations that differ from the dimensional ratios of actual structures in order to facilitate understanding of the contents of the disclosure. Furthermore, identical or common elements are designated by the same reference numerals throughout the embodiments, and redundant explanations will be omitted. Furthermore, the specific configurations shown in the embodiments and drawings are intended to facilitate understanding of the contents of the present disclosure, and the present disclosure is not limited to the specific configurations shown in the drawings.

[0011] In the fluid simulation method of this embodiment (hereinafter sometimes simply referred to as the "simulation method"), the state in which a fluid containing a plurality of types of fluid materials flows within a chamber is calculated using a computer.

[0012] [computer] 1 is a perspective view showing a computer for executing the fluid simulation method of this embodiment. The computer 1 of this embodiment includes a main body 1a, a keyboard 1b, a mouse 1c, and a display device 1d. The main body 1a is provided with, for example, a central processing unit (CPU), a ROM, a working memory, a storage device such as a magnetic disk, and disk drive devices 1a1 and 1a2. The storage device has software and the like stored in advance for executing the simulation method of this embodiment.

[0013] [fluid] FIG. 2 is a perspective view showing the fluid 3 flowing inside the chamber 2. The fluid 3 in this embodiment contains multiple types of fluid materials 4. There are no particular limitations on the fluid materials 4 as long as they constitute the fluid 3. An unvulcanized rubber material or an uncured resin material is used as the fluid material 4 in this embodiment. Examples of rubber materials include natural rubber (NR), butadiene rubber (BR), and styrene butadiene rubber (SBR).

[0014] The number of types of fluid materials 4 in this embodiment is not particularly limited. In this embodiment, four types are set, including a first fluid material 4A, a second fluid material 4B, a third fluid material 4C, and a fourth fluid material 4D. These first to fourth fluid materials 4A to 4D have different slip characteristics on the wall surface 7 of the chamber 2.

[0015] [Chamber] The chamber 2 of this embodiment is formed in a cylindrical shape and has a wall surface 7 that defines an internal space 8. The chamber 2 of this embodiment is configured to include a branch chamber 5 and a main chamber 6.

[0016] [Branch chamber] The branch chamber 5 of this embodiment is for causing the fluid materials 4 (in this example, first to fourth fluid materials 4A to 4D) to flow and flow into the main chamber 6. One end (upstream side) of the branch chamber 5 of this embodiment is connected to, for example, a screw-type extruder (not shown) for supplying the fluid materials 4.

[0017] The branch chamber 5 includes a first branch chamber 5A, a second branch chamber 5B, a third branch chamber 5C, and a fourth branch chamber 5D. The first branch chamber 5A to the fourth branch chamber 5D are used to allow the first fluid material 4A to the fourth fluid material 4D to flow into the main chamber 6, respectively.

[0018] [Main Chamber] The main chamber 6 of this embodiment is for allowing a fluid 3 containing multiple types of fluid materials 4 (in this example, a first fluid material 4A to a fourth fluid material 4D) to flow. One end (upstream side) of the main chamber 6 is provided with a junction 9 for connecting the other ends (downstream sides) of the branch chambers 5 (in this example, a first branch chamber 5A to a fourth branch chamber 5D). As a result, an internal space 8 surrounded by a wall surface 7 is continuously formed in the chamber 2 from the branch chambers 5 to the main chamber 6.

[0019] A fluid 3 obtained by joining fluid materials 4 (in this example, first fluid material 4A to fourth fluid material 4D) supplied from each branch chamber 5 (in this example, first branch chamber 5A to fourth branch chamber 5D) is supplied to the main chamber 6. Then, in the main chamber 6, the fluid 3 (multiple types of fluid materials 4) is pushed from one end (upstream side) to the other end (downstream side).

[0020] Incidentally, when the fluid 3 contains multiple types of fluid materials 4 (in this example, first to fourth fluid materials 4A to 4D), as in this embodiment, the slip velocity of the fluid 3 relative to the wall surface 7 is considered to change depending on the proportion of the fluid materials 4 present in the vicinity of the wall surface 7. Therefore, in order to perform a flow calculation of such a fluid 3, it is important to calculate the flow state taking into account the change in slip velocity.

[0021] [Fluid Simulation Method (First Embodiment)] In the simulation method of this embodiment, the flow state of the fluid 3 is calculated taking into consideration the slip velocity that changes depending on the proportion of the fluid material 4 near the wall surface 7. Fig. 3 is a flowchart showing the processing procedure of the fluid simulation of this embodiment.

[0022] [Enter chamber model] In the simulation method of this embodiment, first, a chamber model is input to the computer 1 (step S1). Fig. 4 is a conceptual diagram showing the chamber model 11 and the space model 12 of this embodiment. Fig. 5 is a partial cross-sectional view of the main chamber model 16.

[0023] The chamber model 11 is a model of the chamber 2 (shown in FIG. 2). In step S1 of this embodiment, the chamber 2 is modeled (discretized) with a finite number of elements G(i) based on the design data (design parameters) of the chamber 2 to be analyzed. As a result, in step S1, the chamber model 11 having a wall surface 19 (shown in FIG. 5) is set.

[0024] The chamber model 11 of this embodiment is configured to include a branch chamber model 15 and a main chamber model 16.

[0025] The branch chamber model 15 is a model of the branch chamber 5 (shown in FIG. 2). The branch chamber model 15 of this embodiment is configured to include a first branch chamber model 15A, a second branch chamber model 15B, a third branch chamber model 15C, and a fourth branch chamber model 15D. These branch chamber models 15A to 15D are models of the first branch chamber 5A to the fourth branch chamber 5D (shown in FIG. 2), respectively.

[0026] The main chamber model 16 is a model of the main chamber 6 (shown in FIG. 2). One end (upstream side) of the main chamber model 16 is provided with a junction 17 for connecting the other ends (downstream sides) of the branch chamber models 15A to 15D. As a result, in the chamber model 11, an internal space 18 (shown in FIG. 5) surrounded by a wall surface 19 is continuously formed from each of the branch chamber models 15A to 15D to the main chamber model 16.

[0027] For example, two-dimensional surface elements or three-dimensional solid elements (solid elements in this example) are used for the elements G(i). A hexahedron is preferable as the solid element because it has high accuracy and makes it easy to set contact surfaces, but a tetrahedron element suitable for expressing complex shapes may also be used. In addition to these elements, three-dimensional solid elements that can be used in software may also be used as the solid elements. Numerical data such as an element number, node numbers (not shown), and node coordinate values ​​are defined for each element G(i). Furthermore, each element G(i) in this embodiment is defined to have such rigidity that it cannot be deformed even when an external force is applied. The chamber model 11 is stored in the computer 1.

[0028] Define spatial model Next, in the simulation method of this embodiment, a space model 12 is defined in which the internal space 18 (shown in FIG. 5) surrounded by the wall surfaces 19 of the chamber model 11 is modeled with a finite number of elements F(i) (step S2).

[0029] In step S2 of this embodiment, the internal space 18 (shown in FIG. 5) of the chamber model 11, which includes the branch chamber model 15 and the main chamber model 16, is discretized into a finite number of elements F(i). This defines a space model 12 that is continuous from the branch chamber model 15 to the main chamber model 16.

[0030] The space model 12 of this embodiment includes a main space model 13 and a branch space model 14. The branch space model 14 includes a first branch space model 14A, a second branch space model 14B, a third branch space model 14C, and a fourth branch space model 14D.

[0031] As shown in Fig. 5, the main space model 13 is defined in the internal space 18 of the main chamber model 16. As shown in Fig. 4, the first branch space model 14A to the fourth branch space model 14D are defined in the internal spaces 18 (not shown) of the first branch chamber model 15A to the fourth branch chamber model 15D, respectively.

[0032] The element division is performed using three-dimensional elements such as tetrahedrons, hexahedrons, and polyhedral cells (polyhedral grids). In this embodiment, Euler elements are used. In each element F(i), physical quantities such as pressure, temperature, and velocity of the fluid model 21 described below, and volume fractions of the fluid material models 22 (first fluid material model 22A to fourth fluid material model 22D) are calculated. The space model 12 is stored in the computer 1.

[0033] Define fluid model Next, in the simulation method of this embodiment, a fluid model 21 including multiple types of fluid material models 22 is defined in the spatial model 12 (step S3). The multiple types of fluid material models 22 are modeled respectively for multiple types of fluid materials 4 (shown in FIG. 2).

[0034] The multiple types of fluid material models 22 in this embodiment include a first fluid material model 22A, a second fluid material model 22B, a third fluid material model 22C, and a fourth fluid material model 22D. These first fluid material model 22A to fourth fluid material model 22D are modeled versions of the first fluid material 4A to fourth fluid material 4D (shown in FIG. 2), respectively.

[0035] The fluid material model 22 of this embodiment is defined by elements (Euler elements) F(i) of the spatial model 12. The first to fourth fluid material models 22A to 22D define the physical quantities of the first to fourth fluid materials 4A to 4D to be analyzed, respectively. The physical quantities include, for example, shear viscosity, specific heat, thermal conductivity, and specific gravity. These physical quantities are defined appropriately based on the descriptions in, for example, Patent Document 1 and Patent Document (JP 2016-043545 A). The fluid model 21 (plural types of fluid material models 22) is stored in the computer 1.

[0036] [Set boundary conditions, etc.] Next, in the simulation method of this embodiment, boundary conditions and the like are set in the computer 1 (step S4). The boundary conditions of this embodiment include the inflow amounts and temperatures of the first to fourth fluid material models 22A to 22D supplied from one ends (supply ports 14Ai to 14Di) of the first to fourth branch space models 14A to 14D, respectively.

[0037] The inflow rate and temperature can be set based on, for example, experimental results using an actual chamber 2 (shown in FIG. 2) or design values ​​of the chamber 2. These inflow rates and temperatures may be set differently for each of the first to fourth fluid material models 22A to 22D, or the same may be set. In this embodiment, the same inflow rate and temperature are set. Furthermore, the boundary conditions in this embodiment include the pressure (pressure=0) at the other end (outlet) 13t of the main space model 13.

[0038] The boundary conditions in this embodiment include the time step of the flow calculation (simulation), the number of iterations in the internal processing, the calculation end time, etc. These conditions are determined arbitrarily depending on the purpose of the simulation, etc.

[0039] The boundary conditions of this embodiment include a wall slip condition with a flow velocity in the fluid material model 22 at the wall surface 19 (shown in FIG. 5) of the chamber model 11. The wall slip condition is a slip velocity V slip (x) is the slip velocity V slip (x) is calculated using the following formula (1).

[0040]

number

[0041] In the above formula (1), x is a number (natural number) assigned to each element F(i) of the spatial model 12 that is in contact with the wall surface 19 of the chamber model 11. Therefore, the slip velocity V slip In (x), the slip velocity at each element F(x) identified by the number x is defined. In this embodiment, the slip velocity V slip (x) is specified by the center point (representative point) 23 of each element F(x) specified by the number x.

[0042] V in the above formula (1) t (x) is the distance D from the wall surface 19 in the normal direction for each element F(x) identified by the number x. wall The velocity component at the position separated by V in the above equation (1) wallm (x) is the velocity component at the wall surface 19 for each element F(x) identified by the number x. These velocity components V t (x) and V wallm (x) is the velocity component of the fluid model 21 parallel to the wall 19. The velocity component V t (x) and V wallm Details of (x) are as described in Patent Document 1 above.

[0043] In the above formula (1), i is a number (natural number) assigned to each fluid material model 22 (shown in FIG. 4). In this embodiment, a first fluid material model 22A to a fourth fluid material model 22D are included. Therefore, the first fluid material model 22A is assigned the number i of "1". The second fluid material model 22B is assigned the number i of "2". The third fluid material model 22C is assigned the number i of "3". The fourth fluid material model 22D is assigned the number i of "4".

[0044] C in the above formula (1) i is the volume fraction of the fluid material model 22 (the first fluid material model 22A to the fourth fluid material model 22D) identified by the number i in each element F(x) identified by the number x. i is the viscosity of each fluid material model 22 (first fluid material model 22A to fourth fluid material model 22D) identified by number i in each element F(x) identified by number x. The viscosity in this embodiment is shear viscosity. For this viscosity, the shear viscosities defined for the first fluid material model 22A to fourth fluid material model 22D (i.e., the shear viscosities of the first fluid material 4A to fourth fluid material 4D) in step S3 of defining the fluid models are used.

[0045] F in the above formula (1) slipi and e i are constants that represent the slip characteristics of the fluid material model 22 identified by the number i. These constants F slipi and e i is determined (identified) in advance by experiment based on the same procedure as in Patent Document 1.

[0046] In this embodiment, in the flow calculation step S5 described later, for each element F(x) of the space model 12 in contact with the wall surface 19, the volume fraction C i and the velocity component V t (x) and V wallm (x) are substituted into the above equation (1). As a result, the slip velocity V of the fluid model 21 arranged in each element F(x) is calculated. slip(x) are calculated respectively. slip (x) is specified by weighting the shear viscosity of each of the first to fourth fluid material models 22A to 22D by the volume fraction of the first to fourth fluid material models 22A to 22D included in the element F(x). Therefore, the simulation method of this embodiment makes it possible to take into account the slip velocity that changes depending on the proportion of the fluid material 4 near the wall surface 19. The boundary conditions are stored in the computer 1.

[0047] [Flow calculation step] Next, in the simulation method of this embodiment, the computer 1 (shown in FIG. 1) performs a flow calculation of the fluid model 21 (flow calculation step S5). In the flow calculation step S5 of this embodiment, the first fluid material model 22A to the fourth fluid material model 22D are caused to flow into one end (supply ports 14Ai to 14Di) of the first branch space model 14A to the fourth branch space model 14D, respectively, based on the boundary conditions, as shown in FIG. 4. Then, in the flow calculation step S5, the first fluid material model 22A to the fourth fluid material model 22D are caused to merge at the main space model 13, and a state in which the fluid model 21 flows (pushes out) to the other end (discharge port) 13t of the main space model 13 is calculated. Such flow calculation is performed for each unit time Tx of the simulation.

[0048] The flow calculation is performed based on the same procedure as in, for example, Patent Document (JP 2016-043545 A). In this embodiment, at the position of each element F(i) of the spatial model 12, velocity components u in three directions (x, y, z) that specify the state of motion of the fluid material model 22, and unknown quantities of pressure p and temperature T that specify the internal state of the material model are calculated. Furthermore, in the flow calculation of this embodiment, the Navier-Stoks equations for incompressible flow are used, and the density of the fluid material model 22 is assumed to be constant.

[0049] In this embodiment, the fluid material model 22 is treated as a fluid over the entire temperature range. Therefore, fluid equations (simultaneous Navier-Stoks equation, mass conservation equation, and energy equation) are solved. Furthermore, in this embodiment, multiphases of multiple types of material models with different shear viscosities η are handled. Therefore, in this embodiment, the VOF (Volume of Fluid) method used in calculating the flow of a free interface is used.

[0050] In the VOF method, the movement of the interfaces of the four first fluid material models 22A to the fourth fluid material model 22D is not directly calculated, but the volume fraction (filling rate) C of the fluid material models 22A to 22D of each element F(i) is calculated. i is defined and the free interface is expressed in an averaged manner.

[0051] In the flow calculation step S5 of this embodiment, calculations are performed until the flow in the fluid model 21 reaches a stable state (i.e., until it converges). This makes it possible to determine the stable state of the fluid model 21. For the flow calculation, for example, commercially available fluid analysis software (e.g., FLUNET or CFX by ANSYS, Inc.) can be used. Figure 6 is a flowchart showing the processing procedure of the flow calculation step S5 of this embodiment.

[0052] [Calculate the motion of the fluid material model] In the flow calculation step S5 of this embodiment, first, the motion of the multiple types of fluid material models 22 (first fluid material model 22A to fourth fluid material model 22D) is calculated (step S51). The motion calculation in step S51 can be performed in the same procedure as in the past. Examples of the motion calculation procedure include steps S51 to S60 of the flow calculation in Patent Document 1 above, and steps S201 to S210 of the motion calculation steps described in Patent Document 1 (JP 2016-043545 A).

[0053] Calculate volume fraction of fluid material model Next, in the flow calculation step S5 of this embodiment, as shown in Fig. 5, the volume fractions of the plurality of types of fluid material models 22 (shown in Fig. 4) are calculated for the fluid model 21 in contact with the wall surface 19 (step S52). In step S52 of this embodiment, the volume fractions C of the first fluid material model 22A to the fourth fluid material model 22D shown in Fig. 4 are calculated for the element F(i) in contact with the wall surface 19 among the elements F(i) constituting the spatial model 12. i (i=1 to 4) are calculated respectively. Each volume fraction is calculated based on the VOF method.

[0054] In the main space model 13, the flow of the fluid model 21 including the first fluid material model 22A to the fourth fluid material model 22D is calculated, so in the element F(i) in contact with the wall surface 19, the volume fraction C of each of the fluid material models 22A to 22D is i is calculated. Meanwhile, in the first branch space model 14A, since only the flow of the first fluid material model 22A is calculated, the volume fraction of the first fluid material model 22A is set to 1.0 in the element F(i) in contact with the wall surface 19. Similarly, in the second branch space model 14B to the fourth branch space model 14D, the volume fraction of the second fluid material model 22B to the fourth fluid material model 22D is set to 1.0 in the element F(i) in contact with the wall surface 19. The volume fractions are stored in the computer 1.

[0055] [Calculate slip velocity for fluid model 21] Next, in the flow calculation step S5 of this embodiment, the volume fraction C of each of the multiple types of fluid material models 22A to 22D is calculated. i (i=1 to 4), the slip velocity V of the fluid model 21 in contact with the wall surface 19 slip (x) is calculated (step S53).

[0056] In step S53 of this embodiment, for each element F(x) of the space model 12 in contact with the wall surface 19, the volume fraction C i and the velocity component V t (x) and V wallm (x) and are substituted into the above equation (1). Volume fraction Ci is the volume fraction C of the first fluid material model 22A to the fourth fluid material model 22D calculated in step S52. i (i=1~4) is used. Velocity component V t (x) and V wallm (x) is calculated by the same procedure as in the conventional method, for example, the method described in Patent Document 1. As a result, in step S53, for each element F(x) of the spatial model 12 that is in contact with the wall surface 19, the slip velocity V slip (x) is calculated.

[0057] In the main space model 13, the flow of the fluid model 21 including the first fluid material model 22A to the fourth fluid material model 22D is calculated, so the volume fraction C i Slip speed V according to slip On the other hand, in the first branch space model 14A, since only the flow of the first fluid material model 22A is calculated, in the element F(i) in contact with the wall surface 19, the slip velocity V based only on the volume fraction (=1.0) of the first fluid material model 22A is calculated. slip Similarly, in the second branch space model 14B to the fourth branch space model 14D, in the element F(i) in contact with the wall surface 19, the slip velocity V based on the volume fraction (=1.0) of the second fluid material model 22B to the fourth fluid material model 22D is calculated. slip (x) are calculated respectively. Slip velocity V slip (x) is stored in computer 1.

[0058] [Determine the stable state of the fluid material model] Next, in the flow calculation step S5 of this embodiment, it is determined whether the flow in the fluid model 21 has reached a stable state (whether the calculation has converged) (step S54). In this embodiment, the stable state refers to a state in which the difference between the total supply amount of the first fluid material model 22A to the fourth fluid material model 22D from one end (junction) of the main space model 13 and the discharge amount of the fluid model 21 at the other end 13t of the main space model 13 is within a predetermined range. The determination of the stable state is appropriately performed based on, for example, the processing procedure of step S211 in Patent Document (JP 2016-043545 A).

[0059] If it is determined in step S54 that the flow in the fluid model 21 has stabilized ("Yes" in step S54), the series of processes in the flow calculation step S5 of this embodiment ends, and the next step S6 (shown in FIG. 3) is performed. On the other hand, if it is determined in step S54 that the flow in the fluid model 21 has not stabilized ("No" in step S54), the simulation unit time Tx is advanced by one (step S55), and steps S51 to S54 are performed again. As a result, in the flow calculation step S5, the flow calculation of the fluid model 21 is performed for each simulation unit time Tx until the flow in the fluid model 21 stabilizes.

[0060] In the simulation method of this embodiment, the slip velocity V of the fluid model 21 in contact with the wall surface 19 relative to the wall surface 19 is calculated based on the volume fraction of the multiple types of fluid material models 22 included in the fluid model 21 in contact with the wall surface 19. slip As a result, in the simulation method of this embodiment, the slip velocity V (x) that changes depending on the proportion of the fluid material 4 near the wall surface 19 is calculated. slip Taking (x) into consideration, it becomes possible to calculate the flow state of the fluid 3. Therefore, in this embodiment, it is possible to accurately calculate (close to reality) the state in which multiple types of fluid material models 22 join together and the state in which they are pushed out.

[0061] [Get physical quantity] Next, in the simulation method of this embodiment, the computer 1 (shown in FIG. 1) acquires physical quantities of the fluid model 21 (step S6). The physical quantities include, for example, the velocity, pressure, and temperature of the fluid model 21. In this embodiment, these physical quantities are calculated at the other end (exhaust port) 13t of the main chamber model 16. These physical quantities are calculated appropriately using fluid analysis software. The physical quantities are stored in the computer 1.

[0062] [Evaluate physical quantities] Next, in the simulation method of this embodiment, it is evaluated whether the physical quantities of the fluid model 21 are good or bad (step S7). The good or bad of the physical quantities may be determined by the computer 1 (shown in FIG. 1) or by an operator.

[0063] In step S7 of this embodiment, it is determined whether the physical quantity of the fluid model 21 is equal to or less than a predetermined threshold value. The threshold value is set appropriately depending on, for example, the flow state required for the fluid 3 (shown in FIG. 2) to be analyzed.

[0064] In step S7, if it is determined that the physical quantities of the fluid model 21 are good ("Yes" in step S7), a product is manufactured using the fluid 3 (shown in FIG. 2) (step S8). In step S8, for example, the chamber 2 is manufactured based on the design factors of the chamber 2. Then, in step S8, the fluid 3 containing the fluid material 4 is caused to flow in the manufactured chamber 2, thereby manufacturing a product having a desired shape.

[0065] On the other hand, if it is determined in step S7 that the physical quantities of the fluid model 21 are not satisfactory ("No" in step S7), then, for example, the design factors of the chamber 2 (shown in FIG. 2) and the physical properties of the fluid material 4 are changed (step S9), and steps S1 to S7 are performed again. In this way, in the simulation method of this embodiment, the design factors of the chamber 2 and the physical properties of the fluid material 4 are changed until the physical quantities of the fluid model 21 become satisfactory, making it possible to reliably manufacture products with the desired shape and performance.

[0066] [Fluid Simulation Method (Second Embodiment)] In the flow calculation step S5 of the embodiments described above, the joining and extrusion states of the fluid material models 22 are calculated as shown in FIG. 4 , but the present invention is not limited to this. For example, the flow calculation step S5 may calculate the state in which multiple types of fluid material models 22 are mixed in a Banbury mixer (not shown), as in Patent Document 1. Furthermore, the flow calculation step S5 may calculate the state in which the fluid model 21 (multiple types of fluid material models 22A-22D) are molded into a predetermined shape. In this embodiment, as in the previous embodiments, the slip velocity with respect to the wall surface 19 is calculated taking into account the fluid material 4 present near the wall surface 19, so that the mixed and molded states of the fluid material models 22 can be calculated with high accuracy (close to reality).

[0067] Although particularly preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the illustrated embodiments and can be modified and implemented in various forms. [Example]

[0068] Based on the processing procedure of FIG. 3, the state in which a fluid containing a plurality of types of fluid materials flows within a chamber was calculated using a computer (Example and Comparative Example).

[0069] In the example, the slip velocity of the fluid model in contact with the wall surface was calculated based on the volume fraction of multiple types of fluid material models, based on the processing procedure shown in Figure 6. On the other hand, in the comparative example, the slip velocity was calculated based on a procedure similar to that of the conventional method, without taking into account the volume fraction of multiple types of fluid material models. Common specifications are as follows: 1st to 4th fluid material models: Specific gravity: 1.11×103 (kg / m 3 ) Specific heat: 1.43 x 103 (J / kg K) Thermal conductivity: 0.323 W / m K Initial temperature, wall temperature: 100℃ Inflow rate: 0.05kg / s Slip characteristic constants: First fluid material model: F slip1 :2.38×10 6 e1:0.235 Secondary fluid material model: F slip2 :1.34×10 6 e2:0.285 Tertiary fluid material model: F slip3 :3.56×10 6 e3:0.201 Fourth fluid material model: F slip4 :3.01×10 6 e4:0.269

[0070] Fig. 7 is a contour diagram showing the flow velocity of the fluid material model of the example. Fig. 8 is a contour diagram showing the flow velocity of the fluid material model of the comparative example. Figs. 7 and 8 show the flow velocity as viewed from the outlet side of the main chamber model, with lighter colors indicating faster flow velocity.

[0071] 7 and 8, the left wall surface has a large proportion of the first fluid material model 22A due to the supply from the first branch chamber model 15A shown in Fig. 4. The upper wall surface has a large proportion of the second fluid material model 22B, the right wall surface has a large proportion of the third fluid material model 22C, and the lower wall surface has a large proportion of the fourth fluid material model 22D.

[0072] 8, in the comparative example, the slip velocity relative to the wall was calculated to be the same for the upper wall, the left wall, the lower wall, and the right wall. Therefore, in the comparative example, it was not possible to take into account the slip velocity that changes depending on the proportion of fluid material near the wall.

[0073] As shown in Figure 7, in this example, the slip speeds calculated for the walls were larger in the order of the upper wall, the left wall, the lower wall, and the right wall. That is, the slip speed of the second fluid material model 22B was calculated to be the largest, and the slip speed of the third fluid material model 22C was calculated to be the smallest. This is due to the constant F, which indicates the slip characteristics defined for each fluid material model. slip and e. Therefore, in the example, the flow state of the fluid can be calculated taking into account the slip velocity that changes depending on the proportion of the fluid material near the wall surface.

[0074] [Note] The present disclosure includes the following aspects.

[0075] [Disclosure 1] A simulation method for calculating, using a computer, a state in which a fluid containing a plurality of types of fluid materials flows in a chamber, the method comprising: modeling the chamber and inputting a chamber model having walls into the computer; defining a space model in which an internal space surrounded by the wall surfaces of the chamber model is modeled using a finite number of elements; defining a fluid model including a plurality of fluid material models in which the plurality of fluid materials are modeled in the spatial model; and a step of performing a flow calculation of the fluid model by the computer; The step of performing the flow calculation includes: Calculating volume fractions of the plurality of types of fluid material models for the fluid model in contact with the wall surface; and calculating a slip velocity of a fluid model in contact with the wall surface based on the volume fraction. Fluid simulation methods. [Disclosure 2] The fluid simulation method according to Disclosure 1, wherein the slip velocity is calculated using the following formula (1):

number

[0076] S52 Step to calculate volume fraction S53 Step to calculate slip speed

Claims

1. A simulation method for calculating, using a computer, a state in which a fluid containing a plurality of types of fluid materials flows in a chamber, the method comprising: modeling the chamber and inputting a chamber model having walls into the computer; defining a space model in which an internal space surrounded by the wall surfaces of the chamber model is modeled using a finite number of elements; defining a fluid model including a plurality of fluid material models in which the plurality of fluid materials are modeled in the spatial model; and a step of performing a flow calculation of the fluid model by the computer; The step of performing the flow calculation includes: Calculating volume fractions of the plurality of types of fluid material models for the fluid model in contact with the wall surface; and calculating a slip velocity of a fluid model in contact with the wall surface relative to the wall surface based on the volume fraction. Fluid simulation methods.

2. The fluid simulation method according to claim 1 , wherein the slip velocity is calculated by the following equation (1): [Equation 1] where: x: Number assigned to each element in contact with the wall (natural number) V slip (x): slip speed α: slip ratio V t (x): Distance D from the wall surface in the normal direction wall Velocity components of the fluid model at positions separated by V wallm (x): Velocity component of the fluid model at the wall i: Number assigned to each fluid material model (natural number) C ｉ : Volume fraction of each fluid material model η ｉ : Viscosity of each fluid material model F slipi , e i : Constants that indicate the slip characteristics of each fluid material model

3. 3. The fluid simulation method according to claim 1, wherein the fluid material is an unvulcanized rubber material or an uncured resin material.

4. 4. The fluid simulation method according to claim 1, wherein the step of performing flow calculation calculates at least one of a state in which the plurality of types of fluid material models meet, a state in which they are mixed, a state in which they are extruded, and a state in which they are molded.

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