Complex micro-channel target time domain finite difference shunt field analysis automatic modeling method and system

Abstract

The invention discloses a complex micro-channel target time domain finite difference shunt field analysis automatic modeling method and system, and the method comprises the steps: building a micro-channel target structure geometric model, carrying out the tetrahedral mesh division of the geometric model through ANSYS-APDL, and obtaining the tetrahedral subdivision information; determining the spatial positions of two end points of the FDTD ridge line relative to the tetrahedron, inferring the position relationship between the ridge line and the tetrahedron, and calculating the position information of the intersection point when the ridge line intersects with the tetrahedron; media of different material numbers on the two sides of an interface are judged, length information between an intersection point and the two end points of an FDTD ridge line is calculated, then the line ratio is obtained, the material numbers are distributed through the line ratio information, FDTD grids are generated, and modeling of the complex micro-channel structure is completed. According to the method, the problem that modeling of a complex micro-channel target is difficult is effectively solved, a micro-channel flow field analysis platform can efficiently and rapidly construct a complex micro-channel structure, and the solving capacity is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the field of complex microchannel modeling, and specifically relates to a complex microchannel target time-domain finite difference flow field analysis automatic modeling method and system. Background Art

[0002] Microfluidic thermal management technology has attracted extensive attention from domestic and foreign scholars in recent years due to its high heat transfer coefficient, compact size and good compatibility with highly integrated chips. This technology usually forms microfluidic channels of different numbers and structures by etching on the chip substrate, injects coolant into the channel through an external system, and uses the heat absorption capacity of the coolant to take away the heat generated by the chip, thereby achieving the purpose of heat dissipation.

[0003] In the research and design of microfluidic thermal management technology, simulation tools and research methods play a vital role. The Finite Difference Time Domain (FDTD) method has been widely used in the field of simulation and modeling due to its significant advantages, such as intuitiveness, easy programming, wide applicability and natural parallel processing capabilities. However, FDTD faces certain limitations when dealing with complex geometric structures, especially in accurately representing irregular shapes and details.

[0004] Therefore, it is particularly important to develop modeling technology that can effectively cope with complex geometric structures. Only through precise modeling technology can we accurately capture the actual geometric features, improve the reliability and accuracy of simulation results, and provide more sophisticated and realistic simulations for solving complex flow field problems such as microfluidics. Summary of the invention

[0005] The purpose of the present invention is to provide a method and system for automatic modeling of time-domain finite-difference flow field analysis of complex microfluidic targets, which effectively solves the difficulty of modeling complex microfluidic targets, enables the microfluidic flow field analysis platform to efficiently and quickly construct complex microfluidic structures, and significantly improves the solution capability.

[0006] The technical solution to achieve the purpose of the present invention is:

[0007] An automatic modeling method for finite-difference time-domain flow field analysis of a complex microfluidic target comprises the following steps:

[0008] Step 1, establish a microfluidic target structure geometric model, use ANSYS-APDL to perform tetrahedral meshing on the geometric model, and obtain tetrahedral meshing information, including tetrahedron number, material number, node number, and three-dimensional coordinate information of its tetrahedron nodes;

[0009] Step 2: Determine the spatial positions of the two endpoints of the FDTD edge line relative to the tetrahedron, infer the positional relationship between the edge line and the tetrahedron, and calculate the position information of the intersection point when the edge line intersects the tetrahedron;

[0010] Step 3: Judge the media with different material numbers on both sides of the interface, calculate the length information between the intersection point and the two endpoints of the FDTD edge line, and then obtain the line ratio. Allocate the material number through the line ratio information, generate the FDTD grid, and complete the modeling of the complex microchannel structure.

[0011] Furthermore, when the edge line intersects the tetrahedron, the calculation of the position information of the intersection point is as follows:

[0012]

[0013] Among them, the parameter d = -(x n x A +y n y A +x z z A ), where x H , y H , z H are the coordinates of the intersection point H of the edge line and the interface or boundary surface, x A , y A , z A , x B , y B , z B are the coordinates of the two vertices of the interface or boundary surface, and x n , y n , z n is the coordinate of the unit normal vector n of the interface or boundary surface of the tetrahedron.

[0014] Furthermore, the judgment of the media with different material numbers on both sides of the interface specifically includes:

[0015] Judge the relationship between the reference vector and the normal vector: Calculate the dot product of the unit normal vector n and the reference vector m. If m·n > 0, it means that the unit normal vector n points to the side with the larger material number, otherwise it points to the side with the smaller material number;

[0016] Judge the relationship between the edge line and the normal vector: Calculate the dot product magnitudes of the two vectors and of the edge line and the unit normal vector n respectively. If the dot product is greater than 0, the line segment corresponding to this vector is located in the material pointed to by the unit normal vector, otherwise it is in the material on the other side; E and F are the two endpoints E and F of the FDTD grid edge line.

[0017] Further, allocating material numbers through line ratio information includes: if the ridge line occupies a relatively large proportion in a certain material number medium, select to allocate this material number to the FDTD grid in this direction.

[0018] Further, it also includes: quickly identifying different boundary conditions according to the material number and performing corresponding processing.

[0019] Further, quickly identifying different boundary conditions and performing corresponding processing specifically includes: after step approximation, the addition range of the boundary conditions is set through the grids of different material numbers, and the area where the material numbers of adjacent grids are different is determined as the boundary, and the boundary conditions are set.

[0020] Further, it also includes: after processing the boundary conditions, performing flow field calculation according to the microchannel flow field simulation method.

[0021] A complex microchannel target time-domain finite-difference flow field analysis automatic modeling system includes:

[0022] A tetrahedral mesh generation unit, which establishes a geometric model of the microchannel target structure, performs tetrahedral mesh generation on the geometric model using ANSYS-APDL, and obtains tetrahedral meshing information, including the number, material number, node number of the tetrahedron, and the three-dimensional coordinate information of its tetrahedral nodes;

[0023] An intersection calculation unit of the ridge line and the tetrahedron, which determines the spatial positions of the two endpoints of the FDTD ridge line relative to the tetrahedron, infers the positional relationship between the ridge line and the tetrahedron, and calculates the position information of the intersection point when the ridge line intersects the tetrahedron;

[0024] A complex microchannel structure modeling unit, which performs medium judgment of different material numbers on both sides of the interface, calculates the length information between the intersection point and the two endpoints of the FDTD ridge line, and then obtains the line ratio, allocates material numbers through the line ratio information, generates the FDTD grid, and completes the modeling of the complex microchannel structure.

[0025] A complex microchannel target time-domain finite-difference flow field analysis automatic modeling device includes: a memory, a processor, and a computer program stored on the memory, and when the processor executes the computer program, it implements the steps of the complex microchannel target time-domain finite-difference flow field analysis automatic modeling method.

[0026] A computer storage medium stores an executable program, and when the executable program is executed by a processor, it implements the steps of the complex microchannel target time-domain finite-difference flow field analysis automatic modeling method.

[0027] Compared with the prior art, the remarkable advantages of the present invention are:

[0028] (1) The present invention can solve the problem of modeling complex irregular structures by the finite-difference time-domain method, capture actual geometric features, and improve the reliability and accuracy of simulation results.

[0029] (2) The present invention can achieve a faster modeling speed for the complex structure of the target compared with the traditional finite-difference time-domain method, and reduce the time required for modeling.

[0030] (3) The present invention is not only applicable to common microchannel structures, but also can effectively process microchannel structures with various complex geometric shapes, has wide applicability and good adaptability, and can meet the requirements of different fields and application scenarios. Description of the Drawings

[0031] Figure 1 It is a diagram showing the relationship between vertices and tetrahedrons.

[0032] Figure 2 It is a schematic diagram showing the relationship between edges and the dividing surface or interface of tetrahedrons.

[0033] Figure 3 It is a schematic diagram showing the position of a point. Figure 3 In (a) of [reference], it is a schematic diagram showing that H is inside triangle ABC. Figure 3 In (b) of [reference], it is a schematic diagram showing that H is outside triangle ABC.

[0034] Figure 4 It is a schematic diagram of vectors.

[0035] Figure 5 It is a schematic diagram showing that an edge passes through a surface and the intersection point is inside the surface.

[0036] Figure 6 It is Figure 5 A schematic diagram of the dividing surface in the case of Figure 6 In (a) of [reference], it is a schematic diagram of the interface between a medium and water. Figure 6 In (b) of [reference], it is a schematic diagram of the interface between a medium and air. Figure 6 In (c) of [reference], it is a schematic diagram of the interface between water and air.

[0037] Figure 7 It is a schematic diagram showing the position where an edge line does not pass through a triangular surface. Figure 7 In (a) of [reference], it is a schematic diagram showing the position where an edge is not parallel to the surface. Figure 7 In (b) of [reference], it is a schematic diagram showing the position where an edge is parallel to the surface.

[0038] Figure 8 It is Figure 7 A schematic diagram of the dividing surface in the case of Figure 8 In (a) of [reference], it is a schematic diagram of the interface between a medium and water. Figure 8 In (b) of [reference], it is a schematic diagram of the interface between a medium and air. Figure 8 In (c) of [reference], it is a schematic diagram of the interface between water and air.

[0039] Figure 9 It is a flow chart of automatic modeling for flow field calculation.

[0040] Figure 10 It is a modeling diagram of a serpentine microchannel. Figure 10 In (a) is the modeling diagram of ANSYS - APDL. Figure 10 In (b) is the automatic modeling diagram of FDTD.

[0041] Figure 11 It is the flow field distribution diagram in the X direction. Figure 11 In (a) is the flow field distribution diagram in the X direction of COMSOL. Figure 11 In (b) is the flow field distribution diagram in the X direction of FDTD.

[0042] Figure 12 It is the flow field distribution diagram in the Y direction. Figure 12 In (a) is the flow field distribution diagram in the Y direction of COMSOL. Figure 12 In (b) is the flow field distribution diagram in the Y direction of FDTD.

[0043] Figure 13 It is the error comparison calculation diagram. Specific implementation mode

[0044] The present invention will be further described in detail below with reference to the accompanying drawings.

[0045] Combined with Figure 9 , the present invention is an automatic modeling method for time - domain finite - difference flow field analysis of complex microchannels, and the steps are as follows:

[0046] The first step is to establish a geometric structure model of the microchannel, use ANSYS - APDL to perform tetrahedral mesh division on the geometric structure, and obtain the numbers of the divided tetrahedrons, material numbers, node numbers, and three - dimensional coordinate information of the nodes.

[0047] The second step is the judgment of internal points and edge lines. The judgment process of internal points and edge lines includes determining the spatial positions of the two endpoints of the FDTD edge line relative to the tetrahedron, so as to infer the relative position relationship between the edge line and the tetrahedron.

[0048] The third step is to calculate the position information of the intersection point when the edge line intersects the tetrahedron.

[0049] The fourth step is to calculate the length information between the intersection point and the two endpoints of the FDTD grid edge line after obtaining the intersection point position, and then obtain the line ratio. Using the line ratio information, generate the FDTD grid to achieve precise modeling of the complex microchannel structure.

[0050] The fifth step is to quickly identify different boundary conditions according to the material numbers after grid generation and perform corresponding processing.

[0051] In the sixth step, after adding the boundary condition identification, perform the flow field calculation according to the microchannel flow field simulation method.

[0052] In the first step described above, establish a geometric structure model, use ANSYS-APDL to perform tetrahedral mesh division on the geometric structure, and obtain the numbers of the divided tetrahedrons, material numbers, node numbers, and three-dimensional coordinate information of the nodes.

[0053] In the second step described above, judge the interior points and edge lines. The judgment process of the interior points and edge lines includes determining the spatial positions of the two endpoints of the FDTD edge line relative to the tetrahedron, so as to infer the relative position relationship between the edge line and the tetrahedron; before analyzing the relationship between the edge line and the tetrahedron, it is first necessary to determine whether the two endpoints of the edge line are located inside the tetrahedron, because these endpoints may be located inside the tetrahedron or outside. The specific judgment method is as follows: As Figure 1 shown, it is necessary to calculate the volumes of the new tetrahedrons (a total of four) formed by any three of the four vertices A, B, C, and D of the tetrahedron and the volume of the original tetrahedron for the target point E. By comparing the sum of the volumes of the four new tetrahedrons with the volume of the original tetrahedron, it is judged whether the point E is inside the divided tetrahedron.

[0054] V ABCD =V EABC +V EABD +V EABC +V EBCD (1) If the formula (1) is satisfied, then the point E is an interior point inside the tetrahedron. If not, the vertex is outside the tetrahedron. If both vertices of an edge line are outside the tetrahedron, then this edge line is located outside the microchannel fluid calculation domain, and this situation is not considered.

[0055] In the third step described above, if the edge line is not in other dielectric materials, it is necessary to judge the different position situations of the edge line with the tetrahedron interface or the boundary surface. For easy analysis, assume that the two endpoints of an edge of the FDTD grid are E(x E ,y E ,z E ) and F(x F ,y F ,z F ), the intersection point of the edge line and the interface or the boundary surface is H(x H ,y H ,z H ), and the three vertices of the triangular interface or the boundary surface are A(x A ,y A ,z A ), B(x B ,y B ,z B ), C(xC , y C , z C ), and the unit normal vector of the plane is n = (x n , y n , z n ), as Figure 2 shown. Since the coordinates of the three vertices of triangle ABC are known, according to the definition of vector cross product, it can be known that the unit normal vector n of the triangle plane ABC can be obtained from any two side vectors, such as:

[0056]

[0057] The line where EF is located intersects the plane ABC where the triangle is located, and there must be an intersection point. Let point H be the intersection point. Since the coordinates of the three vertices of the tetrahedron triangle are directly obtained from the meshing file and are known, the normal vector of the plane where the triangle is located is easy to calculate as n = (x n , y n , z n ), specifically as follows:

[0058]

[0059] The analytical equation of the plane where the triangle is located can be expressed as:

[0060] x n (x - x A ) + y n (y - y A ) + x z (z - z A ) = 0 (4)

[0061] Since the coordinates of the two vertices E and F of the FDTD grid edge are known, the equation of the line where EF is located can be expressed as follows:

[0062]

[0063] Then, according to the mathematical equations of the line and the plane, the coordinates (x H , y H , z H ) of the intersection point H can be obtained, which is expressed as follows:

[0064]

[0065] Among them, d = -(x n x A + y n y A + x z z A ), and here the position coordinates of H are known. After obtaining the coordinates of H, the vector Since the size and direction are both known, the areas of triangles HAB, HBC, and HCA can be easily obtained. To determine whether the intersection point H lies on the triangular surface defined by vertices A, B, and C, we will calculate the areas of all possible new triangles formed by H and any two vertices among A, B, and C, and compare them with the area of the original triangle ABC. If the area of the newly formed triangle is equal to the area of the original triangle, it can be inferred that the intersection point H lies on the triangular surface; otherwise, H is not on this surface. Whether the intersection point H is inside or outside the triangle is as shown in Figure 3 as shown. As Figure 3 shown in (a) of ABC , there is S HAB = S HBC + S HAC . The intersection point H may be inside the triangle, on the side of the triangle, or at the vertex. In this case, there are two situations: the edge line is parallel to the triangular surface (within the triangular surface) or one vertex of the edge line is on the triangular surface and the other vertex is at any position.

[0066] In the fourth step described in Figure 4 , quickly finding the material attribution of the part where the edge line passes through is the prerequisite for modeling. The method for judging the media with different material numbers on both sides of the interface is as follows. Taking passing through the interface as an example, the schematic diagram is as shown in Figure 4 . Similarly, the two endpoints of the edge are E and F respectively, the intersection point of the edge line and the interface or the boundary surface is H, the three vertices of the triangular interface or the boundary surface are A, B, C, and D respectively, and the unit normal vector of the surface is m. For the convenience of subsequent analysis, the reference vector m always points from the intersection point H to the fourth vertex D of the tetrahedron and always points to the side with the larger material number. Assume that at this time, the material number on the left side of the interface is larger, which is 5, and the material number on the other side is smaller, which is 4, and the unit normal vector of the surface points to the side with the smaller material number.

[0067] The steps for determining the material attribution on both sides of the edge are as follows.

[0068] (1) Judge the relationship between the reference vector and the normal vector. Calculate the dot product of the unit normal vector n and the reference vector m. If m·n is greater than 0, it means that the unit normal vector n points to the side with the larger material number; otherwise, it points to the side with the smaller material number. Figure 5 As shown in

[0069] (2) Judge the relationship between the edge line and the normal vector. Calculate the dot products of the two vectors and of the edge line with the unit normal vector n respectively. If the dot product is greater than 0, the line segment corresponding to this vector is located in the material pointed to by the unit normal vector; otherwise, it is in the material on the other side. In Figure 5 , there is less than 0. Therefore, the vector is located in the medium with the material number 5, and the vector Located in the medium with material number 4.

[0070] (3) Calculate the line ratio. The dissection size in the x - direction of the FDTD grid is known. The lengths of the vectors and have also been obtained in the previous subsection. By dividing the two, the line ratio can be obtained, and then the line ratio is stored in an array.

[0071] (4) Assign material numbers. Compare according to the calculated line ratio. If the proportion of the edge line in a certain material - numbered medium is larger, then select to assign the material number to the FDTD grid in that direction.

[0072] The above only elaborates on the method for judging the position relationship between the edge line and the interface or boundary surface in the x - direction and calculating the line ratio. This method is also applicable to the y and z directions, and the specific content will not be elaborated further. The purpose of judging the position relationship between the edge line and the boundary surface or interface is to calculate the line ratio for stepped - approximation modeling.

[0073] According to the above discussion, there are three different position relationships between the edge line and the boundary surface in the x - direction. Next, it will be described in detail:

[0074] (1) The edge passes through the surface and the intersection point is inside the surface, as shown in the schematic Figure 5 : When the intersection point H is inside the triangle, the edge line can be directly marked according to the coordinates of H. If the grid edge line is truncated, the line lengths of each part of the truncated edge line and The micro - channel model materials involved in the current research and analysis mainly include media (such as silicon), air, and water. Combining these materials for differentiation, the material differentiation schematic diagram is as follows. As Figure 6 shown, if is greater than then the FDTD grid material is classified as the material number pointed to by the vector otherwise it is classified as the material number of the material pointed to by the vector .

[0075] (2) When the edge line of the FDTD grid does not pass through the triangular interface, it is divided into Figure 7 two cases. One is that one vertex of the edge line is inside the surface and the edge line is not parallel to the surface, as shown in Figure 7 (a) below, and the other is that the edge line is parallel to the surface and the vertex is inside the surface, as shown in Figure 7 (b) below. For the case shown in Figure 7(a), the material differentiation schematic diagram is as Figure 8 shown; in this case, only one vertex of the edge line is located on the interface or boundary surface, and the rest are located in the medium of the same material number. At this time, the line ratio calculation is 1, and the FDTD grid is classified into the category with the larger material number. For Figure 7(b) In the case where one vertex of the middle ridge line lies on the interface or boundary surface and is parallel to the plane, first, it is confirmed whether it belongs to the situation shown in (b) by judging whether the dot product of the ridge line and the surface normal vector is zero. If the dot product is zero, it means that the ridge line is parallel to the plane, and then it is judged which of the two vertices lies within the surface. For the material division of the FDTD grid, by default, the ridge line is divided into the category with a larger material number, because it is easier to understand, so the schematic diagram of the dielectric interface is not elaborated here.

[0076] In the fifth step described above, after completing the FDTD grid modeling of the three-dimensional target model, the boundary can be adaptively divided according to the FDTD grid information of the model. The addition of boundary conditions is usually located at the junction of two materials. Since the material numbers corresponding to each grid have been obtained in the fourth step, it is easy to find the FDTD grids on both sides of the interface and set the boundary conditions accordingly.

[0077] In the sixth step described above, after the boundary conditions are set, the flow field simulation of the target model can be automatically carried out in combination with the FDTD flow field simulation platform.

[0078] To verify the correctness and effectiveness of the present invention, the flow field simulation of a right-angle corner microchannel is analyzed below.

[0079] The serpentine microchannel structure is composed of two semi-circular channels spliced reversely. The total length in the X direction is 7 mm, the total length in the Y direction is 7 mm, the thickness in the Z direction is 1 mm, the outer radius of the arc is 2 mm, the inner radius is 1 mm, the inlet and outlet are distributed in the Y direction, and the cross-sectional sizes are both The number of grids in the X, Y, and Z directions are 140, 140, and 10 respectively. The time step of the FDTD flow field simulation algorithm is selected as 10 -4 seconds, and the total number of time steps is 15000 steps. A fixed flow rate is given in the positive Y direction along the XOZ plane, and the flow rate magnitude u 0 is 10 mm / s, and the other surfaces are fixed walls. The flow velocities at the center points of the grids in the X and Y directions are selected for plotting and observation. The FDTD calculation results are compared with the calculation results of the software COMSOL, and the flow field distribution diagrams in the X and Y directions are obtained as shown in Figure 11 、 12 shown, and the maximum relative error between the FDTD calculation results and the COMSOL calculation results is about 4.5%, as shown in Figure 13 shown.

[0080] This embodiment also provides a complex microchannel target time-domain finite-difference flow field analysis automatic modeling system, including:

[0081] Tetrahedral mesh division unit, establish a geometric model of the target structure of the microchannel, use ANSYS-APDL to perform tetrahedral mesh division on the geometric model, and obtain tetrahedral subdivision information, including the number, material number, node number of the tetrahedron, and the three-dimensional coordinate information of its tetrahedral nodes;

[0082] Edge line and tetrahedron intersection point calculation unit, determine the spatial positions of the two endpoints of the FDTD edge line relative to the tetrahedron, infer the positional relationship between the edge line and the tetrahedron, and calculate the position information of the intersection point when the edge line intersects the tetrahedron;

[0083] Complex microchannel structure modeling unit, perform medium judgment of different material numbers on both sides of the interface, calculate the length information between the intersection point and the two endpoints of the FDTD edge line, and then obtain the line ratio. Allocate material numbers through the line ratio information, generate the FDTD grid, and complete the modeling of the complex microchannel structure.

[0084] This embodiment also provides a complex microchannel target time-domain finite-difference flow field analysis automatic modeling device, including: a memory, a processor, and a computer program stored on the memory. When the processor executes the computer program, it implements the steps of the complex microchannel target time-domain finite-difference flow field analysis automatic modeling method.

[0085] This embodiment also provides a computer storage medium. The computer storage medium stores an executable program, and when the executable program is executed by a processor, it implements the steps of the complex microchannel target time-domain finite-difference flow field analysis automatic modeling method.

[0086] Based on the time-domain finite-difference flow field analysis platform and combined with geometric grid information, the present invention realizes the automatic solution of the intersection points of the edge line and the tetrahedron, and uses the step approximation method to process the grid area, efficiently completing the modeling of the complex microchannel target. In addition, this technology numbers different material domains, solves the problem of adaptive recognition and setting of boundary conditions, and ensures the accuracy and integrity of the modeling. The present invention effectively solves the problem of difficult modeling of complex microchannel targets, enables the microchannel flow field analysis platform to efficiently and quickly construct complex microchannel structures, and significantly improves the solving ability.

[0087] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0088] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. An automatic modeling method for finite-difference time-domain flow field analysis of complex microchannel targets, characterized in that: Includes steps: Step 1, establish a microfluidic target structure geometric model, use ANSYS-APDL to perform tetrahedral meshing on the geometric model, and obtain tetrahedral meshing information, including tetrahedron number, material number, node number, and three-dimensional coordinate information of its tetrahedron nodes; Step 2, determine the spatial positions of the two endpoints of the FDTD edge line relative to the tetrahedron, infer the positional relationship between the edge line and the tetrahedron, and calculate the position information of the intersection when the edge line intersects the tetrahedron; Step 3: judge the media with different material numbers on both sides of the interface, calculate the length information between the intersection and the two end points of the FDTD edge line, and then obtain the line ratio. The material number is assigned according to the line ratio information, and the FDTD grid is generated to complete the modeling of the complex microfluidic structure.

2. The automatic modeling method for finite-difference time-domain flow field analysis of a complex microchannel target according to claim 1 is characterized in that: When the edge intersects the tetrahedron, the position information of the intersection is calculated as: Among them, parameter d = -(x n x A +y n y A +x z z A ), x H ,y H ,z H is the coordinate of the intersection point H between the edge line and the interface or boundary surface, x A ,y A ,z A 、x B ,y B ,z B are the coordinates of the two vertices of the interface or boundary surface, x n ,y n ,z n The unit normal vector n coordinate of the tetrahedron's interface or boundary surface.

3. The automatic modeling method for finite-difference time-domain flow field analysis of a complex microchannel target according to claim 1 is characterized in that: To judge the media with different material numbers on both sides of the interface, including: Determine the relationship between the reference vector and the normal vector: Calculate the dot product of the unit normal vector n and the reference vector m. If m·n is greater than 0, it means that the unit normal vector n points to the side with a larger material number, otherwise it points to the side with a smaller material number. Determine the relationship between the edge and the normal vector: calculate the two vectors of the edge separately and The size of the dot product with the unit normal vector n. If the dot product is greater than 0, the line segment corresponding to the vector is located in the material pointed to by the unit normal vector, otherwise it is in the material on the other side. E and F are the two endpoints E and F of the FDTD grid edge.

4. The automatic modeling method for finite-difference time-domain flow field analysis of a complex microchannel target according to claim 1 is characterized in that: The material number is assigned by line ratio information including: if the edge line accounts for a larger proportion in a medium with a certain material number, the FDTD grid in the direction of the material number is selected.

5. The automatic modeling method for finite-difference time-domain flow field analysis of a complex microchannel target according to claim 1 is characterized in that: Also includes: Based on the material number, different boundary conditions can be quickly identified and handled accordingly.

6. The automatic modeling method for finite-difference time-domain flow field analysis of a complex microchannel target according to claim 5, characterized in that: The specific steps of quickly identifying different boundary conditions and performing corresponding processing include: after step approximation, the range of adding boundary conditions is set through grids with different material numbers, and areas with different adjacent grid material numbers are determined to be boundaries, and boundary conditions are set.

7. The automatic modeling method for finite-difference time-domain flow field analysis of a complex microchannel target according to claim 5, characterized in that: Also includes: After the boundary conditions are processed, the flow field calculation is performed according to the microfluidic flow field simulation method.

8. An automatic modeling system for finite-difference time-domain flow field analysis of complex microchannel targets, characterized in that: include: Tetrahedral meshing unit is used to establish the geometric model of the microfluidic target structure. The geometric model is tetrahedral meshed using ANSYS-APDL to obtain tetrahedral segmentation information, including the tetrahedral number, material number, node number and the three-dimensional coordinate information of its tetrahedral nodes; The edge line and tetrahedron intersection calculation unit determines the spatial positions of the two endpoints of the FDTD edge line relative to the tetrahedron, infers the positional relationship between the edge line and the tetrahedron, and calculates the position information of the intersection when the edge line intersects the tetrahedron; The complex microfluidic structure modeling unit determines the media with different material numbers on both sides of the interface, calculates the length information between the intersection and the two end points of the FDTD edge line, and then obtains the line ratio. The material number is assigned according to the line ratio information, and the FDTD grid is generated to complete the modeling of the complex microfluidic structure.

9. An automatic modeling device for finite-difference time-domain flow field analysis of complex microchannel targets, characterized in that: include: A memory, a processor and a computer program stored in the memory, wherein when the processor executes the computer program, the steps of the automatic modeling method for complex microfluidic target time-domain finite-difference flow field analysis according to any one of claims 1 to 7 are implemented.

10. A computer storage medium, characterized in that: The computer storage medium stores an executable program, and the executable program is executed by a processor to implement the steps of the automatic modeling method for complex microchannel target finite-difference time-domain flow field analysis as described in any one of claims 1-7.

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