Grid attribute determination method and device suitable for lattice Boltzmann method

Abstract

The invention is suitable for the technical field of computers, and provides a grid attribute determination method and device suitable for a lattice Boltzmann method.The method comprises the steps that a flow channel structure of flow field simulation is obtained, and the surface of the flow channel structure is converted into a spatial discrete unit; determining a computational domain of the flow field simulation according to the flow channel structure, wherein a plurality of regular orthogonal cubic grids are uniformly arranged in the computational domain; generating straight lines penetrating through the cubic grid to obtain a corresponding straight line set; and for any straight line in the straight line set, determining the intersection condition of the straight line and the discrete unit of the space, and determining the grid attribute of the cubic grid through which the straight line passes according to the intersection condition of the straight line and the discrete unit of the space. Through the method, the efficiency of determining the grid attributes can be improved.

Description

Technical Field

[0001] This application belongs to the field of computer technology, and in particular relates to a method, apparatus, device, computer-readable storage medium, and computer program product for determining mesh properties applicable to the lattice Boltzmann method. Background Technology

[0002] With the development of computational fluid dynamics (CFD) technology, the Lattice Boltzmann Method (LBM) has become an effective tool for simulating complex flow fields. LBM discretizes the fluid region into a large number of regularly and uniformly distributed grid points, and uses a statistical model of microscopic particle collisions and migrations to simulate macroscopic fluid behavior.

[0003] In LBM, the core of fluid computation is to simulate the macroscopic behavior of fluids through the collision and migration process of the distribution function, and the correct determination of the grid properties of the grid points is the key to ensuring the accuracy and stability of fluid computation.

[0004] Traditional methods for determining mesh attributes typically employ a point-by-point approach. For example, for each mesh point, the relationship between that mesh point and the various spatial structures transformed from the flow channel surface is determined to establish its mesh attribute. In complex flow channel structures, due to the sheer number of mesh points and the vast number of transformed spatial structures, point-by-point traversal is computationally expensive and inefficient. Summary of the Invention

[0005] This application provides a method and apparatus for determining mesh properties using the lattice Boltzmann method, which can solve the problem of low efficiency in determining mesh properties.

[0006] In a first aspect, embodiments of this application provide a method for determining mesh properties applicable to the lattice Boltzmann method, including:

[0007] Obtain the flow channel structure for flow field simulation, and transform the surface of the flow channel structure into discrete spatial units;

[0008] The computational domain for the flow field simulation is determined based on the flow channel structure, and multiple regular orthogonal cubic meshes are uniformly arranged within the computational domain.

[0009] Generate straight lines that pass through the cube grid to obtain the corresponding set of straight lines;

[0010] For any line in the set of lines, determine the intersection of the line with the discrete unit of the space, and based on the intersection of the line with the discrete unit of the space, determine the mesh properties of the cube mesh through which the line passes.

[0011] Since the lines in the line set pass through the cubic grid, the intersection of these lines with the discrete units in space reflects the intersection of the cubic grids they pass through with the discrete units in space. Therefore, determining the grid attributes of the cubic grids through which the line passes based on this intersection information improves the accuracy of the determined grid attributes. Furthermore, determining the grid attributes of the cubic grids through which the line passes requires only a few judgments—perhaps only one judgment is needed to determine the grid attributes of all the cubic grids the line passes through (e.g., if the line does not intersect with any of the discrete units when it passes through three cubic grids, it means that the three cubic grids also do not intersect with the discrete unit, meaning only one judgment is needed instead of three). This significantly reduces the amount of discrete unit data that needs to be judged, thus greatly improving the efficiency of determining grid attributes. Furthermore, since the cubic mesh within the computational domain is a uniformly arranged, regular orthogonal cubic mesh, when it is necessary to generate lines passing through cubic meshes that satisfy the above conditions, the number of lines generated will be less than the number of lines generated passing through cubic meshes that do not satisfy the above conditions. In this way, less computation is required to determine the intersection of fewer lines with discrete units in space, thereby further improving the efficiency of determining mesh properties.

[0012] Secondly, embodiments of this application provide a mesh property determination apparatus applicable to the lattice Boltzmann method, comprising:

[0013] The flow channel structure acquisition module is used to acquire the flow channel structure for flow field simulation and convert the surface of the flow channel structure into discrete spatial units.

[0014] The computational domain determination module is used to determine the computational domain for the flow field simulation based on the flow channel structure, wherein multiple regular orthogonal cubic meshes are uniformly arranged within the computational domain.

[0015] The line set determination module is used to generate lines passing through the cube grid to obtain the corresponding line set;

[0016] The grid attribute determination module is used to determine the intersection of any line in the set of lines with the discrete units of the space, and to determine the grid attribute of the cube grid through which the line passes based on the intersection of the line with the discrete units of the space.

[0017] Thirdly, embodiments of this application provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method described in the first aspect.

[0018] Fourthly, embodiments of this application provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method described in the first aspect.

[0019] Fifthly, embodiments of this application provide a computer program product that, when run on an electronic device, causes the electronic device to execute the method described in the first aspect above.

[0020] It is understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0022] Figure 1 This is a flowchart illustrating a method for determining mesh properties applicable to the lattice Boltzmann method, provided in an embodiment of this application.

[0023] Figure 2 This is a schematic diagram of the surface discretization of the flow channel structure into triangular units according to an embodiment of this application;

[0024] Figure 3 This is an embodiment provided by this application. Figure 2 A schematic cross-sectional view of the flow channel structure of the control valve shown;

[0025] Figure 4 This is a schematic diagram of the mesh properties of the flow channel structure of a control valve provided in an embodiment of this application;

[0026] Figure 5 This is a schematic diagram of the speedup ratio of the lattice Boltzmann method for determining the mesh properties of different flow channel structures, provided in an embodiment of this application.

[0027] Figure 6 This is a schematic diagram of a mesh property determination device applicable to the lattice Boltzmann method provided in an embodiment of this application;

[0028] Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0029] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0030] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0031] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0032] References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0033] Currently, computational fluid dynamics (LBM) has become a powerful tool for simulating complex flow fields, and the correct determination of the mesh properties of grid points in LBM is crucial to ensuring the accuracy and stability of fluid dynamics calculations. For example, boundary treatment methods used in numerical methods for computational fluid dynamics, such as the immersed moving boundary (IMB) method and the interpolation bounce back method, all require determining the mesh properties of grid points. These mesh properties include the type of the mesh (or grid point), such as solid point, fluid point, fluid boundary point, solid boundary point, etc.

[0034] When determining the grid properties of grid points, a point-by-point judgment method is usually used. However, since the computational cost of point-by-point traversal is extremely high, its computational efficiency is low.

[0035] To improve the computational efficiency of determining mesh properties, embodiments of this application provide a method for determining mesh properties applicable to the lattice Boltzmann method.

[0036] In this method, a straight line is generated that passes through a cubic mesh within the computational domain of the flow field simulation. The mesh properties of the cubic mesh through which the line passes are determined by the intersection of this line with discrete elements in the space transformed from the surface of the flow channel structure. In other words, this method replaces determining the positional relationship between the cubic mesh and each discrete element with judging the intersection of the line and the discrete elements, thereby reducing the amount of discrete element data that needs to be judged and greatly improving the efficiency of determining mesh properties.

[0037] The following description, in conjunction with the accompanying drawings, describes an embodiment of the present application that provides a method applicable to lattice Boltzmann.

[0038] Figure 1 The illustration shows a flowchart of a mesh property determination method applicable to the lattice Boltzmann method provided in an embodiment of this application. This method can be applied to electronic devices, such as servers, personal computers, and laptops, as detailed below:

[0039] S11. Obtain the flow channel structure for flow field simulation and convert the surface of the flow channel structure into discrete spatial units.

[0040] Flow field simulation is an important application area of ​​CFD, which is a method of numerically simulating and analyzing the physical processes of fluid flow using computer simulation technology. It is mainly used to study the motion laws, velocity distribution, pressure distribution, temperature changes, and other related physical quantities of fluids under different conditions.

[0041] Here, the flow channel structure refers to the structure corresponding to the fluid flow channel in the case of flow field simulation.

[0042] In this embodiment, mesh generation software can be used to discretize the surface of the flow channel structure into discrete spatial elements, resulting in a set of corresponding discrete spatial elements. The shape of these discrete elements can be triangular or other shapes, and is not limited here. Common mesh generation software such as ANSYS Workbench and HyperMesh can discretize the surface of complex flow channel structures into triangular spatial elements, resulting in a set of corresponding triangular spatial elements.

[0043] S12. Based on the above flow channel structure, determine the computational domain for the above flow field simulation. Multiple regular orthogonal cubic meshes are uniformly arranged within the computational domain.

[0044] In flow field simulation, the computational domain is the geometric space used to describe fluid flow. Within this space, the physical behavior of the fluid (such as velocity, pressure, and temperature) is simulated and calculated.

[0045] In this embodiment of the application, the boundary of the computational domain is composed of the actual boundary of the fluid flow (such as the wall of the flow channel structure). In reality, the boundary of the computational domain can also be composed of artificially set boundaries (such as inlet, outlet, symmetry boundary, etc.).

[0046] like Figure 2 As shown, assuming the flow field simulation case is a complex flow channel structure of a control valve, the cross-sectional view of the flow channel structure of this control valve is as follows. Figure 3 As shown ( Figure 3 The darker colored areas represent the cross-sectional areas. When performing flow field simulations, it is necessary to identify the boundaries of the flow channels of the regulating valve for subsequent calculations. Figure 2 In the middle, the left side of the flow channel structure is the inlet, and the right side is the outlet, located in... Figure 2 The black wireframe outside the upper flow channel structure represents the computational domain for fluid simulation, within which a cubic mesh is arranged. Figure 2 (Not shown to avoid severe visual occlusion). Assuming the cube mesh has 100×100×1000 elements along the x, y, and z axes, then... Figure 2 The total number of cubic meshes is 10 million. After discretizing the surface of the flow channel structure of the control valve into triangular elements (assuming a total of 11,386 triangles), we obtain... Figure 2 A schematic diagram of the flow channel structure located at the bottom.

[0047] In this embodiment, considering that a highly symmetrical and regular mesh structure can simplify the calculation process and improve computational efficiency, the cubic mesh within the computational domain is set as multiple uniformly arranged regular orthogonal cubic meshes. The cells of the orthogonal cubic mesh are arranged regularly, with each cell having the same shape and size, typically a cube or cuboid. This regularity makes the mesh generation process very simple, allowing for rapid generation using simple mathematical formulas or mesh generation tools.

[0048] S13. Generate straight lines that pass through the above cube grid to obtain the corresponding set of straight lines.

[0049] The line can pass through two or three cube grids, as long as the cube grids passed by each line are not exactly the same. After generating the line, a corresponding set of lines is constructed based on it.

[0050] For example, when generating a straight line that passes through two cube grids, you can select two coordinates in the two cube grids and then connect the two coordinates. Since these two coordinates belong to different cube grids, connecting these two coordinates is equivalent to generating a straight line that passes through the two cube grids.

[0051] For example, a straight line passing through three or more cubic grids can be generated using the Bresenham algorithm. The Bresenham algorithm is a method for drawing straight lines in a grid system; it generates lines by determining which grid points are closest to the ideal line.

[0052] S14. For any line in the set of lines, determine the intersection of the line with the discrete unit of the space, and determine the grid properties of the cube grid through which the line passes based on the intersection of the line with the discrete unit of the space.

[0053] Among them, the above intersection situations include: (1) the line intersects with the discrete unit, and the number of intersection points is 1; (2) the line does not intersect with any discrete unit, and the number of intersection points is 0; (3) the line is inside the discrete unit, and the number of intersection points is infinite.

[0054] When a straight line intersects a discrete element, the cube mesh that the line passes through may intersect the discrete element or may not intersect it. When a straight line does not intersect any discrete element, it means that all the cube meshes that the line passes through also do not intersect the discrete element. In this case, the mesh attribute of these cube meshes can be determined as a solid point, and the solid point belongs to the mesh attribute of the aforementioned cube mesh.

[0055] The mesh attributes include the type of mesh (or mesh points), such as solid points, fluid points, fluid boundary points, solid boundary points, etc. Optionally, after determining the mesh attributes, fluid calculations can be performed based on these attributes, which will not be elaborated here.

[0056] In this embodiment, Plücker coordinates can be used to determine the intersection of a line with a discrete unit in space. Plücker coordinates are an efficient method for representing lines and performing geometric calculations, particularly in computer graphics and robotics. They can represent lines in three-dimensional space and facilitate calculations of intersections between lines and planes, and between lines themselves.

[0057] In this embodiment, since the lines in the line set pass through the cubic grid, the intersection of the line with the discrete unit in space reflects the intersection of the cubic grid through which the line passes with the discrete unit in space. Therefore, determining the grid attribute of the cubic grid through which the line passes based on the intersection of the line with the discrete unit in space improves the accuracy of the determined grid attribute. Furthermore, since determining the grid attribute of the cubic grid through which the line passes requires only a few judgments—perhaps only one judgment is needed—the grid attributes of all the cubic grids through which the line passes can be determined (e.g., if the line does not intersect with the discrete unit when it passes through three cubic grids, it indicates that the three cubic grids also do not intersect with the discrete unit, meaning only one judgment is needed instead of three to obtain the grid attributes of the three cubic grids). This significantly reduces the amount of discrete unit data that needs to be judged, thereby greatly improving the efficiency of determining the grid attribute. Furthermore, since the cubic mesh within the computational domain is a uniformly arranged, regular orthogonal cubic mesh, when it is necessary to generate lines passing through cubic meshes that satisfy the above conditions, the number of lines generated will be less than the number of lines generated passing through cubic meshes that do not satisfy the above conditions. In this way, less computation is required to determine the intersection of fewer lines with discrete units in space, thereby further improving the efficiency of determining mesh properties.

[0058] In some embodiments, S13, generating straight lines passing through the cube mesh to obtain a corresponding set of straight lines, includes:

[0059] Generate a set of lines that pass through the center point of the orthogonal cube grid according to the above rules and are parallel to the coordinate axes.

[0060] In this embodiment, considering that the coordinate axes can be the x-axis, y-axis, and z-axis, straight lines passing through the center point of the orthogonal cube mesh and parallel to the x-axis, y-axis, and z-axis can be generated respectively, resulting in the corresponding set of straight lines. Assume the set of straight lines corresponding to the lines passing through the center point of the orthogonal cube mesh and parallel to the x-axis is Φ. x Then the set of lines corresponding to the lines that pass through the center point of the orthogonal cube grid and are parallel to the y-axis can be denoted as Φ. y The set of lines corresponding to lines passing through the center point of an orthogonal cubic grid and parallel to the z-axis can be denoted as Φ. z With Φ x For example, it is the set of straight lines connecting the center points of the grid with the same y-coordinate and z-coordinate, that is, for Φ x For the straight lines in the diagram, the y-coordinate and z-coordinate of each line are the same, but the x-coordinate is different; for Φ yFor straight lines in the diagram, the x-coordinate and z-coordinate of each line are the same, but the y-coordinate is different; for Φ z For straight lines in the diagram, the x-coordinate and y-coordinate of each line are the same, but the z-coordinate is different. If the number of orthogonal cubic meshes in the flow field is a×b×c, then Φ x The number of lines in the diagram is b×c, Φ y The number of lines in the equation is a×c, Φ z The number of lines in the equation is a × b.

[0061] In this embodiment, considering that a straight line passes through the center point of an orthogonal cubic grid, such as passing through the center points of two orthogonal cubic grids and being parallel to the coordinate axes, the equation of the straight line is equivalent to the intersection of two planes. Therefore, such a connection is the simplest and the fastest way to generate a straight line. Furthermore, the analytical method for the coordinates of a straight line is simple, and correspondingly, calculating the intersection point of the straight line with the discrete units in space is also simple. Therefore, using the above method to generate a straight line results in a faster generation speed and also improves the speed of subsequent calculation of the intersection point.

[0062] In some embodiments, the number of lines in the set is greater than 1, the set of lines corresponds to the coordinate axes, and the lines in the set of lines are parallel to the corresponding coordinate axes. In step S14, for any line in the set of lines, the intersection of the line with the discrete unit of the space is determined, and based on the intersection of the line with the discrete unit of the space, the mesh properties of the cube mesh through which the line passes are determined, including:

[0063] A1. For any line in each of the above-mentioned line sets, determine the intersection of the line with the discrete unit of the space, and based on the intersection of the line with the discrete unit of the space, determine the grid properties of the cube grid through which the line passes, and obtain the grid properties to be adjusted for each cube grid.

[0064] A2. For any of the above-mentioned cube meshes, determine the final mesh attributes of the cube meshes based on the various mesh attributes to be adjusted corresponding to the cube meshes.

[0065] Specifically, assume there are 3 sets of lines, namely Φ x Φ y and Φ z Then we can first determine Φ x The grid properties of the cube mesh through which the straight line passes are determined, and then Φ is determined separately. y and Φ z The grid properties of the cube grids through which the straight lines pass are determined. Finally, the grid properties of each cube grid are determined by combining the grid properties determined by different straight lines. Of course, Φ can also be determined first.y (or Φ) z The grid properties of the cube mesh that the straight line in the diagram passes through are determined, and then Φ is determined separately. x and Φ z (Φ x and Φ y The grid properties of the cube grids through which the straight lines pass are determined. Finally, the grid properties of each cube grid are determined by combining the grid properties determined by different straight lines.

[0066] Optionally, in mesh attributes, boundary points (such as fluid boundary points and solid boundary points) have the highest priority, while the priority of fluid points and solid points is lower than that of boundary points. For example, if the mesh attribute of a cube mesh is determined to be a solid point based on the intersection of lines in a certain set of lines, and if the mesh attribute of the cube mesh is determined to be a boundary point (or solid boundary point) based on the intersection of lines in another set of lines, then the mesh attribute of the cube mesh will change from solid point to boundary point (or solid boundary point). It should be noted that once the mesh attribute of a cube mesh is determined to be a solid point based on the intersection of lines in a certain set of lines, the mesh attribute of the cube mesh determined based on the intersection of lines in other sets of lines can only be a solid point (i.e., a pure solid point) or a boundary point (i.e., a solid boundary point).

[0067] Similarly, when the grid property of a cube mesh is determined to be a boundary point (or fluid boundary point) based on the intersection of lines in a certain set of lines, if the grid property of the cube mesh is determined to be a fluid point based on the intersection of lines in another set of lines, then the grid property of the cube mesh will remain unchanged as a boundary point.

[0068] Since the number of lines in a set is greater than one, and the lines in the set are parallel to their corresponding coordinate axes, the same cubic mesh may be traversed by lines from different sets, meaning the same cubic mesh may be traversed by lines in different directions. Furthermore, since the intersection patterns of lines in different directions with discrete spatial elements are likely to differ (meaning the same cubic mesh may intersect with discrete spatial elements in different directions), determining the individual mesh attributes to be adjusted based on the intersection patterns of the lines traversing the cubic mesh, and then determining the final mesh attributes based on these individual attributes, helps improve the accuracy of the final mesh attributes.

[0069] In some embodiments, when determining the mesh properties of the cube mesh through which the straight line passes based on the intersection of the straight line with the discrete units of the space, S14 includes:

[0070] B1. If the above-mentioned straight line intersects with at least one discrete unit of the above-mentioned space, determine the target coordinate components of each intersection point to obtain an intersection point set. Wherein, the target coordinate component of the above-mentioned intersection point is the coordinate value of the above-mentioned intersection point under the target coordinate axis, and the above-mentioned target coordinate axis is the coordinate axis parallel to the above-mentioned straight line.

[0071] For example, for the straight line in Φ x if the straight line intersects with one or more discrete units of the space, since the y coordinate and the z coordinate of the straight line are equal, determine the coordinate values (i.e., x coordinates) of each intersection point under the x coordinate axis to obtain the target coordinate components of the corresponding intersection points, and the target coordinate components of each intersection point form the above-mentioned intersection point set.

[0072] For example, for the straight line in Φ y if the straight line intersects with one or more discrete units of the space, determine the coordinate values of each intersection point under the y coordinate axis to obtain the target coordinate components of the corresponding intersection points, and the target coordinate components of each intersection point form the above-mentioned intersection point set.

[0073] B2. For any cube grid passed through by the above-mentioned straight line, determine whether the target coordinate component of the above-mentioned cube grid satisfies the following solid point condition. If the target coordinate component of the above-mentioned cube grid satisfies the above-mentioned solid point condition, determine that the above-mentioned cube grid is a solid point. If the target coordinate component of the above-mentioned cube grid does not satisfy the above-mentioned solid point condition, count the number of intersection points in the above-mentioned intersection point set whose target coordinate components are less than the target coordinate component of the above-mentioned cube grid, and calculate the distance between the above-mentioned cube grid and each intersection point in the above-mentioned intersection point set respectively. Determine the grid attribute of the above-mentioned cube grid according to the above-mentioned number and the calculated distances.

[0074] Wherein, the above-mentioned solid point condition is: the target coordinate component of the above-mentioned cube grid is less than the difference between the minimum target coordinate component in the above-mentioned intersection point set and the preset allowable distance value, or the target coordinate component of the above-mentioned cube grid is greater than the sum of the maximum target coordinate component in the above-mentioned intersection point set and the above-mentioned allowable distance value.

[0075] Wherein, the preset allowable distance value can be set to N times the grid length of the cube grid, where 0 < N < 1. Optionally, N = 0.5.

[0076] In this embodiment of the application, when a straight line intersects with at least one discrete unit in space, it indicates that the number of intersection points is greater than or equal to 1. Then, it is determined whether the target coordinate component of the cubic mesh is less than the difference between the minimum target coordinate component corresponding to the intersection point in the intersection point set and the allowable distance value, or whether the target coordinate component of the cubic mesh is greater than the sum of the maximum target coordinate component corresponding to the intersection point in the intersection point set and the allowable distance value. If the solid point condition is met, it indicates that the cubic mesh is outside the flow channel. At this time, the cubic mesh is determined to be a solid point.

[0077] If the solid point condition is not met, count the number of intersection points in the intersection point set where the target coordinate component is less than the target coordinate component of the cube mesh, denoted as n. Continue to determine if the distance between the cube mesh and each intersection point in the intersection point set (represented by the absolute value of the difference between the target coordinate component of the cube mesh and the target coordinate component of the intersection point) is less than or equal to the allowable distance value. If it is less than or equal to the allowable distance value and n is even, the cube mesh is determined to be a solid boundary point; if it is less than or equal to the allowable distance value and n is odd, the cube mesh is determined to be a fluid boundary point. If it is not less than the allowable distance value and n is even, the cube mesh is determined to be a pure solid point; if it is not less than the allowable distance value and n is odd, the cube mesh is determined to be a pure fluid point. For example, assuming the target coordinate components in the intersection point set are 1, 2, 4, and 5, and the target coordinate component of the cube mesh is 3, then the number of intersection points in the intersection point set where the target coordinate component is less than the target coordinate component of the cube mesh is n = 2. Calculate the distances of the target coordinate component 3 of the cube mesh to "1", "2", "4", and "5" respectively, resulting in "2", "1", "1", and "2". Assuming a preset allowable distance value of 1.5, the distance "2" is greater than 1.5, and since n is an even number, the cube mesh's mesh attribute is a pure solid point. Figure 3 The mesh properties of the flow channel structure of the regulating valve can be as follows: Figure 4 As shown.

[0078] In this embodiment, when a straight line intersects with a discrete element in space, if the cubic mesh is outside the first or last intersection point (i.e., satisfies the aforementioned solid point condition), it indicates that the cubic mesh is outside the flow channel. In this case, the mesh attribute of the cubic mesh can be directly determined as a solid point. Since the process of determining whether the cubic mesh is outside the first or last intersection point is relatively simple, the above method is beneficial for quickly determining whether the cubic mesh is a solid point.

[0079] In some embodiments, before determining the intersection of any line in the set of lines with the discrete units of the space, the method further includes:

[0080] Generate the bounding boxes of the discrete units in the above space;

[0081] Determine the intersection of the aforementioned straight line with the aforementioned bounding box;

[0082] Correspondingly, S14, when determining the intersection of any line in the set of lines with the discrete units of the space, includes:

[0083] After determining that the above-mentioned straight line intersects with the above-mentioned bounding box, for any straight line in the above-mentioned set of straight lines, determine the intersection situation between the above-mentioned straight line and the discrete unit of the above-mentioned space.

[0084] Of course, if it is determined that the line does not intersect the bounding box, then it is determined that the line does not intersect any discrete unit in the space, and the grid properties of all the cubic grids that the line passes through are solid points.

[0085] Optionally, the bounding box described above is a minimal hexahedron containing triangles with sides parallel to the coordinate axes, and this bounding box can be as follows: Figure 2 The hexahedrons in black, depicted in varying thicknesses, are located on the upper flow channel structure.

[0086] In this embodiment, the intersection of a line and the bounding box is determined by checking whether the line intersects with the six faces corresponding to the bounding box. Specifically, the expressions corresponding to the line and the plane to be judged within the bounding box are first determined. The expression of the line is substituted into the expression of the plane to be judged, and the intersection point between the line and the plane to be judged is determined based on the calculated value.

[0087] Since the structure of a bounding box is simpler than that of discrete units in multiple spaces, it is beneficial to improve the efficiency of the judgment by first determining whether the line intersects with the bounding box, and then determining whether the line intersects with the discrete units of the space within the bounding box after determining that the line intersects with the bounding box.

[0088] In the above description, the mesh attribute includes the mesh type. In practice, this mesh attribute may also include the solid volume percentage. That is, in some embodiments, the above-mentioned mesh attribute also includes the solid volume percentage. The mesh attribute for determining the cube mesh through which the above-mentioned straight line passes includes:

[0089] Calculate the solid volume percentage of the above cubic mesh.

[0090] Solid volume fraction refers to the ratio of the volume of the solid portion to the volume of the space enclosed by the entire mesh in a three-dimensional mesh structure.

[0091] A boundary point is defined as a grid point where the solid volume percentage is not zero. These boundary points can be categorized into fluid boundary points and solid boundary points. Fluid boundary points are located within the flow field domain, while solid boundary points are located within the solid domain.

[0092] Among them, the pure solid point is the point where the solid volume ratio is 1, and the pure fluid point is the point where the solid volume ratio is 0.

[0093] In this embodiment of the application, when calculating the solid volume ratio, the size of the cubic mesh can be determined first. For example, if the cubic mesh consists of N... x ×N y ×N z Composed of voxels, each voxel is a cube with side length a, and the total volume is V. total =(N x ·a)×(N y ·a)×(N z ·a)=N x N y N z a 3 .

[0094] Each voxel is labeled as either "solid" or "void," and the number of solid voxels N is counted. solid Then the solid volume V solid =N solid ·a 3 .

[0095] Calculate the percentage

[0096] In this embodiment, since the solid volume ratio of the cubic mesh is also calculated when determining the mesh properties, corresponding applications can be performed based on this solid volume ratio. For example, in materials science and engineering, performance analysis of porous materials can be conducted.

[0097] To further illustrate the difference between the method provided in this application and the traditional traversal method when determining grid properties, the following description is provided with specific examples.

[0098] As shown in Table 1 below, this comparative example selects three control valves with different levels of complexity, each with a different number of triangular units on its flow channel surface. Secondly, the number of orthogonal cubic meshes in the flow field simulation is varied to verify the efficiency of the method provided in this application embodiment under flow channel models with different mesh counts and complexities.

[0099] Table 1:

[0100] Case Number of triangular units in flow channel structure Control valve 1 11386 Control valve 2 5386 regulating valve 3 2198

[0101] like Figure 5As shown, valve flow channel 1 corresponds to regulating valve 1 in Table 1, valve flow channel 2 corresponds to regulating valve 2, and valve flow channel 3 corresponds to regulating valve 3.

[0102] The time for identifying mesh attributes using traditional methods and the time for identifying mesh attributes using the method provided in this application (hereinafter referred to as "this algorithm") are defined as the speedup ratio. (Refer to...) Figure 5 It can be seen that the speedup ratio increases almost linearly with the increase in the number of mesh elements. Furthermore, comparing different valve flow channel examples shows that the more triangular elements in the valve flow channel, i.e., the more complex the flow channel structure, the greater the speedup ratio of this algorithm. In summary, this algorithm is very suitable for large-scale computations with a large number of mesh elements and flow channel boundaries with very complex structures. At the same time, this algorithm has very high efficiency while ensuring accuracy. In this example, with a mesh count of 34,680,000 and 11,386 triangular faces in the flow channel structure, the speedup ratio can reach a maximum of 1162.

[0103] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0104] Corresponding to the mesh property determination method applicable to the lattice Boltzmann method described in the above embodiments, Figure 3 A structural block diagram of a mesh property determination device applicable to the lattice Boltzmann method provided in an embodiment of this application is shown. For ease of explanation, only the parts related to the embodiments of this application are shown.

[0105] Reference Figure 3 The mesh property determination device 3, applicable to the lattice Boltzmann method, can be used in electronic devices and includes: a flow channel structure acquisition module 31, a computational domain determination module 32, a line set determination module 33, and a mesh property determination module 34. Wherein:

[0106] The flow channel structure acquisition module 31 is used to acquire the flow channel structure for flow field simulation and convert the surface of the flow channel structure into discrete spatial units.

[0107] The computational domain determination module 32 is used to determine the computational domain for the flow field simulation based on the above-mentioned flow channel structure. Multiple regular orthogonal cubic meshes are uniformly arranged within the computational domain.

[0108] The line set determination module 33 is used to generate lines that pass through the above-mentioned cube grid to obtain the corresponding line set.

[0109] The mesh attribute determination module 34 is used to determine the intersection of any line in the set of lines with the discrete units of the space, and to determine the mesh attribute of the cube mesh through which the line passes based on the intersection of the line with the discrete units of the space.

[0110] In this embodiment, since the lines in the line set pass through the cubic grid, the intersection of the line with the discrete unit in space reflects the intersection of the cubic grid through which the line passes with the discrete unit in space. Therefore, determining the grid attribute of the cubic grid through which the line passes based on the intersection of the line with the discrete unit in space improves the accuracy of the determined grid attribute. Furthermore, since determining the grid attribute of the cubic grid through which the line passes requires only a few judgments—perhaps only one judgment is needed—the grid attributes of all the cubic grids through which the line passes can be determined (e.g., if the line does not intersect with the discrete unit when it passes through three cubic grids, it indicates that the three cubic grids also do not intersect with the discrete unit, meaning only one judgment is needed instead of three to obtain the grid attributes of the three cubic grids). This significantly reduces the amount of discrete unit data that needs to be judged, thereby greatly improving the efficiency of determining grid attributes. Furthermore, since the cubic mesh within the computational domain is a uniformly arranged, regular orthogonal cubic mesh, when it is necessary to generate lines passing through cubic meshes that satisfy the above conditions, the number of lines generated will be less than the number of lines generated passing through cubic meshes that do not satisfy the above conditions. In this way, less computation is required to determine the intersection of fewer lines with discrete units in space, thereby further improving the efficiency of determining mesh properties.

[0111] Optionally, the above-mentioned line set determination module 33 is specifically used for:

[0112] Generate a set of lines that pass through the center point of the orthogonal cube grid according to the above rules and are parallel to the coordinate axes.

[0113] Optionally, the number of lines in the aforementioned line set is greater than 1, the aforementioned line set corresponds to the aforementioned coordinate axis, the lines in the aforementioned line set are parallel to the corresponding aforementioned coordinate axis, and the aforementioned mesh attribute determination module 34 includes:

[0114] The grid attribute determination unit is used to determine the intersection of any line in each of the above-mentioned line sets with the discrete unit of the above-mentioned space, and to determine the grid attribute of the cube grid through which the line passes based on the intersection of the line with the discrete unit of the above-mentioned space, so as to obtain the grid attribute to be adjusted for each cube grid.

[0115] The final mesh attribute determination unit is used to determine the final mesh attribute of any of the aforementioned cubic meshes based on the respective mesh attributes to be adjusted corresponding to the aforementioned cubic meshes.

[0116] Optionally, when determining the intersection of the aforementioned line with the discrete elements of the aforementioned space, the aforementioned mesh attribute determination module 34 is specifically used for:

[0117] Obtain the coordinates of the discrete units in the aforementioned space;

[0118] If the coordinates of the discrete units in the space satisfy the relationship corresponding to the line, then the line is determined to intersect with the discrete units in the space; otherwise, the line is determined not to intersect with the discrete units in the space.

[0119] Optionally, when determining the mesh attributes of the cube mesh through which the straight line passes based on the intersection of the straight line with the discrete elements of the space, the mesh attribute determination module 34 is specifically used for:

[0120] If the aforementioned straight line does not intersect with any of the discrete units of the aforementioned space, then all the cubic meshes through which the aforementioned straight line passes are determined to be solid points, and the aforementioned solid points belong to the mesh attributes of the aforementioned cubic meshes.

[0121] Optionally, when determining the mesh attributes of the cube mesh through which the straight line passes based on the intersection of the straight line with the discrete elements of the space, the mesh attribute determination module 34 is specifically used for:

[0122] If the above straight line intersects with at least one discrete unit of the above space, the target coordinate components of each intersection point are determined to obtain the set of intersection points, wherein the target coordinate components of the above intersection points are the coordinate values ​​of the above intersection points under the target coordinate axis, and the above target coordinate axis is the coordinate axis parallel to the above straight line.

[0123] For any cube grid that the above straight line passes through, determine whether the target coordinate component of the cube grid satisfies the following solid point condition. If the target coordinate component of the cube grid satisfies the above solid point condition, then the cube grid is determined to be a solid point. If the target coordinate component of the cube grid does not satisfy the above solid point condition, then count the number of intersection points in the above intersection point set whose target coordinate component is less than the target coordinate component of the cube grid, and calculate the distance between the cube grid and each intersection point in the above intersection point set. Based on the above number and the calculated distances, determine the grid attribute of the cube grid.

[0124] The above-mentioned solid point conditions are: the target coordinate component of the above-mentioned cubic mesh is less than the difference between the minimum target coordinate component in the above-mentioned intersection set and the preset allowable distance value, or the target coordinate component of the above-mentioned cubic mesh is greater than the sum of the maximum target coordinate component in the above-mentioned intersection set and the above-mentioned allowable distance value.

[0125] Optionally, the mesh property determination device 3 for the lattice Boltzmann method provided in this application embodiment further includes:

[0126] The bounding box generation module is used to generate the bounding box of the discrete unit of the space before determining the intersection of the line with the discrete unit of the space for any line in the set of lines.

[0127] The intersection determination module between the line and the bounding box is used to determine the intersection between the line and the bounding box.

[0128] Correspondingly, when determining the intersection of any line in the set of lines with the discrete elements of the space, the aforementioned mesh attribute determination module is specifically used for:

[0129] After determining that the above-mentioned straight line intersects with the above-mentioned bounding box, for any straight line in the above-mentioned set of straight lines, determine the intersection situation between the above-mentioned straight line and the discrete unit of the above-mentioned space.

[0130] Optionally, the aforementioned mesh attributes also include the solid volume ratio. When determining the mesh attributes of the cube mesh through which the aforementioned straight line passes, the mesh attribute determination module 34 is specifically used for:

[0131] Calculate the solid volume percentage of the above cubic mesh.

[0132] It should be noted that the information interaction and execution process between the above-mentioned devices / units are based on the same concept as the method embodiments of this application. For details on their specific functions and technical effects, please refer to the method embodiments section, and they will not be repeated here.

[0133] Figure 4 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 4 As shown, the electronic device 4 of this embodiment includes: at least one processor 40 ( Figure 4 The diagram shows only one processor, a memory 41, and a computer program 42 stored in the memory 41 and executable on the at least one processor 40, which, when executing the computer program 42, performs the steps in any of the above method embodiments.

[0134] The electronic device 4 can be a desktop computer, laptop, handheld computer, or cloud server, etc. This electronic device may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art will understand that... Figure 4 This is merely an example of electronic device 4 and does not constitute a limitation on electronic device 4. It may include more or fewer components than shown, or combine certain components, or different components. For example, it may also include input / output devices, network access devices, etc.

[0135] The processor 40 may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0136] In some embodiments, the memory 41 may be an internal storage unit of the electronic device 4, such as a hard disk or memory of the electronic device 4. In other embodiments, the memory 41 may be an external storage device of the electronic device 4, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the electronic device 4. Furthermore, the memory 41 may include both internal and external storage units of the electronic device 4. The memory 41 is used to store the operating system, applications, bootloader, data, and other programs, such as the program code of the computer program. The memory 41 can also be used to temporarily store data that has been output or will be output.

[0137] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0138] This application also provides a network device, which includes: at least one processor, a memory, and a computer program stored in the memory and executable on the at least one processor, wherein the processor executes the computer program to implement the steps in any of the above method embodiments.

[0139] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, can implement the steps in the above-described method embodiments.

[0140] This application provides a computer program product that, when run on an electronic device, enables the electronic device to implement the steps described in the various method embodiments above.

[0141] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of this application can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying computer program code to a photographic device / electronic device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electrical carrier signals or telecommunication signals.

[0142] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0143] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0144] In the embodiments provided in this application, it should be understood that the disclosed apparatus / network devices and methods can be implemented in other ways. For example, the apparatus / network device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0145] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0146] It should be noted that the information collection process (such as the facial image collection process, fingerprint information collection process, etc.) / feature extraction process involved in this application is carried out with the user's knowledge and permission. That is, the information collection process / feature extraction process complies with the requirements of laws and regulations and does not constitute an act that harms the public interest.

[0147] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for determining mesh properties applicable to the lattice Boltzmann method, characterized in that, include: Obtain the flow channel structure for flow field simulation, and transform the surface of the flow channel structure into discrete spatial units; The computational domain for the flow field simulation is determined based on the flow channel structure, and multiple regular orthogonal cubic meshes are uniformly arranged within the computational domain. Generate straight lines that pass through the cube grid to obtain the corresponding set of straight lines; For any line in the set of lines, determine the intersection of the line with the discrete unit of the space, and based on the intersection of the line with the discrete unit of the space, determine the mesh properties of the cube mesh through which the line passes.

2. The mesh property determination method applicable to the lattice Boltzmann method as described in claim 1, characterized in that, The generation of straight lines passing through the cube mesh, resulting in a corresponding set of straight lines, includes: Generate a set of lines that pass through the center point of the orthogonal cube grid of the given rules and are parallel to the coordinate axes.

3. The mesh property determination method applicable to the lattice Boltzmann method as described in claim 2, characterized in that, The set of lines contains more than one line, the set of lines corresponds to the coordinate axes, and the lines in the set of lines are parallel to the corresponding coordinate axes. For any line in the set of lines, the intersection of the line with the discrete units of the space is determined, and based on the intersection of the line with the discrete units of the space, the mesh attributes of the cube mesh traversed by the line are determined, including: For any line in each set of lines, the intersection of the line with the discrete unit of the space is determined, and based on the intersection of the line with the discrete unit of the space, the grid properties of the cube grid through which the line passes are determined, thus obtaining the grid properties to be adjusted for each cube grid. For any of the cube meshes, the final mesh attributes of the cube mesh are determined based on the various mesh attributes to be adjusted corresponding to the cube mesh.

4. The mesh property determination method applicable to the lattice Boltzmann method as described in claim 1, characterized in that, Determining the intersection of the straight line with the discrete elements of the space includes: Obtain the coordinates of the discrete units in the space; If the coordinates of the discrete units in the space satisfy the relationship corresponding to the line, then the line is determined to intersect the discrete units in the space; otherwise, the line is determined not to intersect the discrete units in the space.

5. The mesh property determination method applicable to the lattice Boltzmann method as described in claim 1, characterized in that, Determining the grid properties of the cube grid traversed by the straight line based on the intersection of the straight line with the discrete units of the space includes: If the straight line does not intersect with any of the discrete units of the space, then all the cubic grids through which the straight line passes are determined to be solid points, and the solid points belong to the grid properties of the cubic grids.

6. The mesh property determination method applicable to the lattice Boltzmann method as described in claim 2, characterized in that, Determining the grid properties of the cube grid traversed by the straight line based on the intersection of the straight line with the discrete units of the space includes: If the straight line intersects with at least one discrete unit of the space, the target coordinate components of each intersection point are determined to obtain a set of intersection points, wherein the target coordinate components of the intersection points are the coordinate values ​​of the intersection points under the target coordinate axis, and the target coordinate axis is a coordinate axis parallel to the straight line; For any cube grid that the straight line passes through, determine whether the target coordinate component of the cube grid satisfies the following solid point condition. If the target coordinate component of the cube grid satisfies the solid point condition, then the cube grid is determined to be a solid point. If the target coordinate component of the cube grid does not satisfy the solid point condition, then count the number of intersection points in the intersection point set whose target coordinate components are less than the target coordinate components of the cube grid. Also, calculate the distance between the cube grid and each intersection point in the intersection point set. Determine the grid attribute of the cube grid based on the number and the calculated distances. The solid point condition is as follows: the target coordinate component of the cube mesh is less than the difference between the minimum target coordinate component in the intersection set and the preset allowable distance value, or the target coordinate component of the cube mesh is greater than the sum of the maximum target coordinate component in the intersection set and the allowable distance value.

7. The mesh property determination method applicable to the lattice Boltzmann method as described in any one of claims 1 to 6, characterized in that, Before determining the intersection of any line in the set of lines with the discrete units of the space, the method further includes: Generate bounding boxes for the discrete units of the space; Determine the intersection of the straight line and the bounding box; Determining the intersection of any line in the set of lines with the discrete units of the space includes: After determining that the line intersects with the bounding box, for any line in the set of lines, determine the intersection of the line with the discrete unit of the space.

8. The mesh property determination method applicable to the lattice Boltzmann method as described in any one of claims 1 to 6, characterized in that, The mesh properties also include the solid volume percentage, and the mesh properties for determining the cube mesh through which the straight line passes include: Calculate the solid volume percentage of the cubic mesh.

9. A mesh property determination device suitable for the lattice Boltzmann method, characterized in that, include: The flow channel structure acquisition module is used to acquire the flow channel structure for flow field simulation and convert the surface of the flow channel structure into discrete spatial units. The computational domain determination module is used to determine the computational domain for the flow field simulation based on the flow channel structure, wherein multiple regular orthogonal cubic meshes are uniformly arranged within the computational domain. The line set determination module is used to generate lines passing through the cube grid to obtain the corresponding line set; The grid attribute determination module is used to determine the intersection of any line in the set of lines with the discrete units of the space, and to determine the grid attribute of the cube grid through which the line passes based on the intersection of the line with the discrete units of the space.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method as described in any one of claims 1 to 8.

11. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 8.

12. A computer program product, characterized in that, Includes a computer program, which, when run, causes the method as described in any one of claims 1 to 8 to be performed.

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