Multi-scale micro-channel flow field high-efficiency analysis method and system based on multi-level grid second-order projection technology

Abstract

This invention discloses an efficient method and system for multi-scale microchannel flow field analysis based on multi-level grid second-order projection technology. The method includes: first, constructing a microchannel geometric model and defining fluid characteristic parameters and boundary conditions; then, constructing a multi-level grid system, with local refinement only in complex regions with significant flow field gradients; combining local temporal refinement technology, setting the time step according to grid scale differences; and utilizing linear interpolation and flux conservation to achieve stable information transfer across grid levels, thereby significantly reducing the overall computational load. Combined with the second-order projection method that introduces intermediate variables, second-order accuracy is achieved in both time and spatial discretization, significantly improving the accuracy of flow field solutions. This method is particularly suitable for complex multi-scale microchannel structures such as serpentine and arc-shaped structures, providing a high-precision and high-efficiency numerical analysis tool for the design and optimization of high-performance microchannel heat sinks.

Description

Technical Field

[0001] This invention belongs to the field of multi-scale microchannel flow field simulation, specifically involving an efficient analysis method and system for multi-scale microchannel flow fields based on multi-level grid second-order projection technology. Background Technology

[0002] Microchannel thermal management technology, with its high heat transfer coefficient, small size, light weight, and powerful heat dissipation capabilities, has become a core solution for heat dissipation in high heat flux density electronic devices. Accurate flow field characteristics and efficient numerical simulation are the key foundations for realizing the design and optimization of microchannel structures.

[0003] The Finite Difference Time Domain (FDTD) method is widely used in flow field simulation due to its simple mathematical form and convenient implementation. However, multi-scale microchannels often contain complex structures such as arcs and serpentine shapes. Traditional FDTD methods use uniform mesh partitioning, which requires global mesh refinement to ensure simulation accuracy in complex regions, leading to a surge in computational load and low efficiency. Furthermore, traditional projection methods for solving incompressible momentum equations can only achieve first-order time accuracy, which is insufficient to meet the high-precision computational requirements of microscale flow fields. These problems result in insufficient accuracy, high resource consumption, and slow solution speed in multi-scale microchannel flow field simulations, severely hindering the design and development of complex microchannels.

[0004] Therefore, it is particularly important to develop a multi-scale microchannel flow field analysis method that combines high accuracy and high efficiency. By optimizing the numerical scheme and innovating the grid technology, the core contradictions of traditional methods can be solved, providing reliable technical support for the optimization of complex microchannel structures. Summary of the Invention

[0005] The purpose of this invention is to provide an efficient method and system for analyzing multi-scale microchannel flow fields based on multi-level grid second-order projection technology. Through the synergistic optimization of second-order accurate numerical solution and adaptive grid partitioning, the solution efficiency is effectively improved and higher accuracy is obtained.

[0006] The technical solution to achieve the purpose of this invention is as follows:

[0007] An efficient method for analyzing multi-scale microchannel flow fields based on multi-level grid second-order projection technology includes the following steps:

[0008] Step 1: Establish a numerical model of the microchannel flow field. Use a multi-level mesh to divide the model and obtain the node information and element information on the model mesh.

[0009] Step 2: In the multi-level mesh, the target area mesh is time-refined based on the time step of the bottom mesh. For the boundary between different mesh levels, interpolation is used to complete the information transfer between different mesh levels.

[0010] Step 3: Solve the incompressible momentum equation using the second-order projection method, introducing intermediate velocity and intermediate pressure, and then decouple the velocity and pressure calculations in the momentum equation.

[0011] Step 4: Iterate through Step 3 to solve the problem. Once the iteration is complete, calculate the flow field value and extract the relevant physical parameters based on the flow field value.

[0012] Furthermore, the numerical model of the microchannel flow field is as follows:

[0013]

[0014]

[0015] in, , , These are velocity vectors. exist directional components, Indicates the pressure exerted on the fluid. Indicates the density of the fluid. Indicates kinematic viscosity.

[0016] Furthermore, the model is further subdivided using multi-level meshes, including:

[0017] The computational domain of the numerical model of the microchannel flow field is globally partitioned to form a bottom-level mesh covering all regions, denoted as . ;

[0018] The target region is further subdivided using a finer mesh than the underlying mesh, resulting in two sets of mesh nodes of different coarse and fine textures existing simultaneously within the target region. The target area grid of the layer is denoted as .

[0019] Furthermore, the first The size of the target region mesh in the layer satisfies the requirement that the size of the mesh in the previous layer must satisfy the condition. , and ,in, , and The first The mesh size in three directions of the target area of ​​the layer. The encryption rate is an even number.

[0020] Furthermore, the target region uses a single-layer target region grid, and the time step of the bottom-layer grid is four times that of the target region grid. Time step of the target region grid They are respectively:

[0021]

[0022]

[0023] in, , and These represent the mesh sizes in three directions of the bottom mesh. , and These represent the grid size in the three directions of the target area.

[0024] Furthermore, the information for different grid levels includes the field values ​​required for the iteration of the target region grid and the flow field numerical updates of the bottom-level grid.

[0025] Furthermore, the field values ​​required for iterating the target region mesh are:

[0026]

[0027] in, Indicates the target area grid number Boundary values ​​of flow field variables for secondary stepping and These represent the underlying mesh in... and Boundary values ​​obtained by time-interpolation.

[0028] Furthermore, the flow field numerical update of the bottom layer grid satisfies flux conservation, that is, the flux of the bottom layer grid is equal to the sum of the flux of the target region grid.

[0029] Furthermore, the incompressible momentum equation is solved using the second-order projection method, introducing intermediate velocity and intermediate pressure to decouple the velocity and pressure calculations in the momentum equation. Specifically, this includes:

[0030] Calculating the intermediate velocity field that does not satisfy the continuity equation, neglecting the pressure gradient term in the incompressible momentum equation, and substituting the no-slip boundary conditions, we obtain:

[0031]

[0032] in, Indicates intermediate speed. Indicates the first Speed ​​at any moment Indicates time progression, Represents the Hamiltonian operator. Indicates kinematic viscosity;

[0033] Calculate the intermediate pressure field, take the divergence of the intermediate velocity field, and construct the pressure Poisson equation by combining it with the incompressible continuity equation. Adapt it to zero pressure gradient and zero pressure boundary conditions to obtain:

[0034]

[0035] in, Indicates intermediate pressure;

[0036] Calculate the velocity and pressure fields at the next moment, correct the intermediate velocity and pressure fields, and obtain the velocity field at the next moment that satisfies the incompressible continuity equation. and pressure field :

[0037]

[0038]

[0039] in, This indicates the density of the fluid.

[0040] A high-efficiency multi-scale microchannel flow field analysis system based on multi-level grid second-order projection technology includes:

[0041] The microchannel flow field solution model is meshed into elements to establish a numerical model of the microchannel flow field. The model is meshed using a multi-level mesh to obtain the node information and element information on the model mesh.

[0042] The cross-level information transmission unit, in a multi-level mesh, uses the time step of the bottom mesh as a reference to perform time densification on the target area mesh. For the boundary between different levels of mesh, interpolation calculation is used to complete the information transmission between different levels of mesh.

[0043] The physical parameter extraction unit uses the second-order projection method to solve the incompressible momentum equation, introduces intermediate velocity and intermediate pressure, and then decouples the velocity and pressure calculations in the momentum equation.

[0044] Extract the unit, perform iterative solution, and after the iteration ends, calculate the flow field value and extract the physical parameters related to the flow field based on the flow field value.

[0045] Compared with the prior art, the significant advantages of this invention are:

[0046] (1) This invention can solve the problem that traditional methods cannot balance accuracy and efficiency, accurately capture the details of complex microchannel flow fields, achieve second-order accuracy in both time and space, and improve the reliability of simulation results.

[0047] (2) The present invention significantly improves computational efficiency and reduces memory usage through local mesh and time-density strategies, thereby greatly reducing the time and resource consumption of flow field analysis.

[0048] (3) The method proposed in this invention is not only applicable to simple straight channels, but can also efficiently handle complex microchannel structures of multiple scales such as serpentine, arc, and multi-branch, and has wide applicability, providing a reliable and efficient numerical tool for the design and performance optimization of microchannel heat sinks. Attached Figure Description

[0049] Figure 1 This is a flowchart of the multi-scale microchannel flow field analysis based on the second-order projection method of multi-level grid.

[0050] Figure 2 This is a schematic diagram illustrating the grid time-based encryption process in the target area.

[0051] Figure 3 This is a schematic diagram of the distribution of pressure interpolation variables in a multi-level grid.

[0052] Figure 4 This is a schematic diagram of the distribution of velocity interpolation variables in a multi-level grid.

[0053] Figure 5 This is a flowchart of the iterative solution process for the velocity and pressure fields of a microchannel in the second-order projection method.

[0054] Figure 6 This is a schematic diagram of a parallel microchannel model with a serpentine arc segment.

[0055] Figure 7 This is a schematic diagram of the distribution of the encrypted microchannel region in the serpentine arc segment.

[0056] Figure 8 This is a diagram showing the flow field characteristics obtained by this method. Figure 8 (a) in the diagram is a schematic diagram of the flow velocity distribution. Figure 8 (b) in the diagram is a schematic diagram of the pressure distribution.

[0057] Figure 9 This is a schematic diagram comparing the flow field characteristics solved by this method with the COMSOL error. Figure 9 (a) in the diagram is a comparison of flow velocity errors. Figure 9 (b) in the diagram is a comparison of pressure errors. Detailed Implementation

[0058] The present invention will now be described in further detail with reference to the accompanying drawings.

[0059] This invention is a multi-scale microchannel flow field analysis method based on multi-level grid second-order projection technology. First, a microchannel geometric model is constructed to clarify fluid characteristic parameters and boundary conditions. Then, a multi-level grid system is built, with local refinement only in complex regions with significant flow field gradients. Combined with local time refinement technology, the time step is set according to the grid scale difference. Linear interpolation and flux conservation are used to achieve stable information transfer across grid levels, thus significantly reducing the overall computational load. By incorporating the second-order projection method that introduces intermediate variables, second-order accuracy is achieved in both time and spatial discretization, significantly improving the accuracy of the flow field solution. This method is particularly suitable for serpentine, arc-shaped, and other multi-scale complex microchannel structures, providing a high-precision and high-efficiency numerical analysis tool for the design and optimization of high-performance microchannel heat sinks. Figure 1 The specific steps of this method are as follows:

[0060] The first step is to establish a numerical model for solving the microchannel, and to divide the model using a multi-level mesh to obtain the node information and element information on the model mesh.

[0061] The fluid characteristics within the microchannel are incompressible flow, steady laminar flow, and are dominated by viscous forces and pressure gradients. The continuity and momentum equations satisfied by the numerical model for solving the microchannel are:

[0062]

[0063]

[0064] in, , , These are velocity vectors. exist directional components, Indicates the pressure exerted on the fluid. Indicates the density of the fluid. Indicates kinematic viscosity.

[0065] Perform multi-level mesh generation for the flow field solution model, specifically including:

[0066] Building the bottom-level mesh: Using coarse-grained cells adapted to the overall geometry of the microchannel, the computational domain of the entire numerical model is globally partitioned to form a bottom-level mesh covering all regions, denoted as . ;

[0067] Target area mesh refinement: Based on the geometry and flow characteristics of the microchannel, identify local areas requiring enhanced accuracy. While maintaining the integrity of the underlying coarse mesh, overlay a finer mesh layer, ensuring that both coarse and fine mesh nodes exist simultaneously in this area. The target area grid of the layer is denoted as . No. The size of the target region mesh in the layer satisfies the requirement that the size of the mesh in the previous layer must satisfy the condition. , and Encryption rate Even numbers are used, usually 2, and all grid layers are encrypted with the same encryption rate.

[0068] The second step is to calculate the time step of the target area grid and the numerical relationship between the underlying grid, and to perform time densification on the target area grid.

[0069] In the second step, the time step of the target region mesh is calculated to correlate with the numerical relationship between the underlying mesh, and the target region mesh is then time-refined. When only one layer of the target region mesh is used, the time step of the underlying mesh is... Time step of the target region grid They are respectively:

[0070]

[0071]

[0072] in, , and These represent the mesh sizes in three directions of the bottom mesh. , and These represent the grid size in three directions of the target area;

[0073] Calculations show that the time step of the bottom-level mesh is four times that of the target region mesh.

[0074] (1)

[0075] Based on the characteristic that each grid layer advances time independently, the time step of each bottom-level grid is... Within this time step, the target region mesh will independently execute four sub-steps. Only after the target region mesh completes its current time step will the underlying mesh advance to the next time step, as shown below. Figure 2 As shown.

[0076] The third step involves time-encrypting the target area grid and then transmitting information between different grid levels.

[0077] In the third step, after time-encrypting the target area grid, information is transferred between different grid levels; at the initial moment of the target area grid, the bottom-level grid is... Time and The solution at time step 1 is processed and used as the boundary conditions for the target region mesh; at the termination time, the calculation results of the target region mesh are fed back to the underlying mesh to update the physical quantities of that region. Based on the above information transfer process, the specific implementation method is as follows:

[0078] (1) Synchronize the boundary values ​​of the target region grid

[0079] During the synchronization process of the target region's grid, the underlying grid is first synchronized... and The time-time values ​​are linearly interpolated, and then the boundary values ​​of each sub-step of the target region grid are obtained through temporal interpolation, such as... Figure 3 As shown. Figure 3 As shown in (a), the pressure boundary value for the target region mesh First of all Interpolation is performed on the surface, by and exist Linear interpolation in the direction is obtained and by and Linear interpolation is obtained Then by and exist Linear interpolation in the direction is obtained .like Figure 3 As shown in (b), finally in Interpolation is performed on the surface, by and The pressure boundary value of the target region mesh is finally obtained by linear interpolation in the z-direction. The specific interpolation expression is as follows:

[0080] (2)

[0081] For the velocity boundary value of the target region mesh ,like Figure 4 As shown in (a), firstly in Interpolation is performed on the surface, by and exist Linear interpolation in the direction is obtained and by and Linear interpolation is obtained Similarly, we can obtain and .

[0082] (3)

[0083] like Figure 4As shown in (b), then by and exist Linear interpolation in the direction is obtained ,Depend on and exist Linear interpolation in the direction is obtained ,at last and exist The arithmetic mean of the directions is obtained :

[0084] (4)

[0085] Since the target region grid will perform four sub-steps after one time step in the bottom-level grid, linear interpolation is also required on the time scale to correspond to each time advance of the target region grid.

[0086] (5)

[0087] in Indicates the target area grid number Boundary values ​​of flow field variables for secondary stepping and The bottom mesh is respectively in and Boundary values ​​obtained by time-interpolation.

[0088] (2) Update the flow field values ​​of the bottom mesh.

[0089] After the time advance of the target region grid is completed, the local solutions obtained from the target region grid need to be fed back to the corresponding underlying grid region. The high-precision solutions of the refinement layer are used to constrain and correct the solutions of the underlying grid. This process must strictly satisfy the flux conservation between the refinement layer and the underlying grid:

[0090] (6

[0091] (7)

[0092] The fourth step is to solve the incompressible momentum equation using the second-order projection method, introducing intermediate velocity and intermediate pressure, and then decoupling the velocity and pressure calculations in the momentum equation.

[0093] In the fourth step, the incompressible momentum equation is solved using the second-order projection method. Intermediate velocity and intermediate pressure are introduced to decouple the velocity and pressure calculations in the momentum equation. Figure 5 As shown:

[0094] (1) Time discretization of the momentum equation. For the incompressible momentum equation, the time discretization is half-step. Discretize at a certain point to achieve the accuracy of the central difference scheme:

[0095] (8)

[0096] (2) Introducing an intermediate variable to separate the incompressible momentum equation. To decouple velocity and pressure, an intermediate velocity is introduced. With intermediate pressure The original equation can be separated into two parts, one concerning the intermediate velocity. The equation and a connection of intermediate pressure With real pressure Relationship:

[0097] (9)

[0098] (3) Update the velocity and pressure fields. By taking the divergence on both sides of the definition of intermediate velocity and applying the divergence-free condition for velocity, the relationship with intermediate pressure can be derived. Poisson equation Solve the Poisson equation for pressure to obtain the intermediate pressure value, substitute it into equation (9), and calculate the velocity at the next moment. and pressure Thus, the flow field at any given time is obtained:

[0099] (10)

[0100] The fifth step is data post-processing, which involves extracting the physical parameters related to the flow field based on the calculated flow field values.

[0101] In the fifth step, the original flow field data obtained from the solution is first preprocessed to remove outliers and optimize data continuity through a smoothing algorithm; then, the core physical parameters are extracted, including the velocity values ​​and pressure distribution in each region; then, the results are visualized by drawing velocity and pressure distribution maps; finally, the parameter report and visualization results are output to provide data support for the optimization of microchannel structures.

[0102] To verify the correctness and effectiveness of this invention, the flow field characteristics of a serpentine arc-shaped parallel microchannel model are analyzed below.

[0103] The following were tested using FDTD and ML-FDTD algorithms respectively. Figure 6The serpentine arc segment parallel microchannel shown was used for simulation. When using the FDTD method, the maximum time step satisfying the stability condition was adopted, with a total of 15,000 iterations. When using the ML-FDTD method, the maximum time step satisfying the stability condition was consistently adopted, and the total iteration time was consistent with that of the FDTD method. The fluid density and dynamic viscosity were respectively... and The inlet velocity along... Positive axis direction, size set to The size of the bottom-level mesh in the ML-FDTD algorithm is... The size of the encryption layer mesh is The mesh-refined areas are the first and second arc segments, specifically as follows: Figure 7 As shown, the range of region one: , The scope of Region Two: , Both encrypted regions have a range in the z-direction. .

[0104] like Figure 8 and Figure 9 For flow field velocity, the maximum relative error of the ML-FDTD algorithm is concentrated in the first arc segment region, at 5.4%. For flow field pressure, the maximum relative error is below 1%. The overall computational cost ratio of the FDTD method to the ML-FDTD method is 8.07:1, and the time ratio is 6.83:1. Considering the additional preprocessing and operations required for program implementation, the time ratio and computational cost ratio can be considered approximately equal. The ML-FDTD method improves computational efficiency by 3.66 times compared to COMSOL. When calculating the flow field of parallel microchannels in serpentine arc segments, the ML-FDTD method significantly improves computational efficiency.

[0105] This embodiment also provides a high-efficiency analysis system for multi-scale microchannel flow fields based on multi-level grid second-order projection technology, including:

[0106] The microchannel flow field solution model is meshed into elements to establish a numerical model of the microchannel flow field. The model is meshed using a multi-level mesh to obtain the node information and element information on the model mesh.

[0107] The cross-level information transmission unit, in a multi-level mesh, uses the time step of the bottom mesh as a reference to perform time densification on the target area mesh. For the boundary between different levels of mesh, interpolation calculation is used to complete the information transmission between different levels of mesh.

[0108] The physical parameter extraction unit uses the second-order projection method to solve the incompressible momentum equation, introduces intermediate velocity and intermediate pressure, and then decouples the velocity and pressure calculations in the momentum equation.

[0109] Extract the unit, perform iterative solution, and after the iteration ends, calculate the flow field value and extract the physical parameters related to the flow field based on the flow field value.

[0110] This invention, based on a finite-difference time-domain (FDTD) flow field analysis platform, constructs an adaptive mesh system to achieve local refinement in complex structural regions and introduces a second-order precision projection algorithm for flow field solution. This effectively solves the bottleneck problems of high computational cost and insufficient accuracy in simulating multi-scale microchannels using traditional uniform mesh methods. Simultaneously, by implementing local time stepping and cross-level information transfer strategies, computational efficiency is significantly improved. This invention not only achieves high-precision simulation of complex microchannel structures but also significantly reduces computation time while maintaining computational reliability, providing a powerful and efficient numerical tool for microchannel heat dissipation design and optimization.

[0111] Obviously, those skilled in the art can make various modifications and variations 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 to the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A highly efficient method for analyzing multi-scale microchannel flow fields based on multi-level grid second-order projection technology, characterized in that, Including the following steps: Step 1: Establish a numerical model of the microchannel flow field. Use a multi-level mesh to divide the model and obtain the node information and element information on the model mesh. Step 2: In the multi-level mesh, the target area mesh is time-refined based on the time step of the bottom mesh. For the boundary between different mesh levels, interpolation is used to complete the information transfer between different mesh levels. Step 3: Solve the incompressible momentum equation using the second-order projection method, introducing intermediate velocity and intermediate pressure, and then decouple the velocity and pressure calculations in the momentum equation. Step 4: Iterate through Step 3 to solve the problem. Once the iteration is complete, calculate the flow field value and extract the relevant physical parameters based on the flow field value.

2. The efficient method for multi-scale microchannel flow field analysis based on multi-level grid second-order projection technology according to claim 1, characterized in that, The numerical model of the microchannel flow field is as follows: in, , , These are velocity vectors. exist directional components, Indicates the pressure exerted on the fluid. Indicates the density of the fluid. Indicates kinematic viscosity.

3. The efficient method for multi-scale microchannel flow field analysis based on multi-level grid second-order projection technology according to claim 1, characterized in that, Using multi-level meshes to partition the model includes: The computational domain of the numerical model of the microchannel flow field is globally partitioned to form a bottom-level mesh covering all regions, denoted as . ; The target region is further subdivided using a finer mesh than the underlying mesh, resulting in two sets of mesh nodes of different coarse and fine textures existing simultaneously within the target region. The target area grid of the layer is denoted as .

4. The efficient method for multi-scale microchannel flow field analysis based on multi-level grid second-order projection technology according to claim 3, characterized in that, No. The size of the target region mesh in the layer satisfies the requirement that the size of the mesh in the previous layer must satisfy the condition. , and ,in, , and The first The mesh size in three directions of the target area of ​​the layer. The encryption rate is an even number.

5. The efficient analysis method for multi-scale microchannel flow fields based on multi-level grid second-order projection technology according to claim 3, characterized in that, The target region uses a single-layer target region mesh, and the time step of the bottom-layer mesh is four times that of the target region mesh. Time step of the target region grid They are respectively: in, , and These represent the mesh sizes in three directions of the bottom mesh. , and These represent the grid size in the three directions of the target area.

6. The efficient method for multi-scale microchannel flow field analysis based on multi-level grid second-order projection technology according to claim 1, characterized in that, Information from different grid levels includes the field values ​​required for iteration of the target region grid and the flow field numerical updates of the bottom-level grid.

7. The efficient method for multi-scale microchannel flow field analysis based on multi-level grid second-order projection technology according to claim 6, characterized in that, The field values ​​required for the iteration of the target region mesh are: in, Indicates the target area grid number Boundary values ​​of flow field variables for secondary stepping and These represent the underlying mesh in... and Boundary values ​​obtained by time-interpolation.

8. The efficient method for multi-scale microchannel flow field analysis based on multi-level grid second-order projection technology according to claim 6, characterized in that, The flow field numerical update of the bottom layer grid satisfies flux conservation, that is, the flux of the bottom layer grid is equal to the sum of the fluxes of the target region grid.

9. The efficient method for multi-scale microchannel flow field analysis based on multi-level grid second-order projection technology according to claim 1, characterized in that, The incompressible momentum equation is solved using the second-order projection method, introducing intermediate velocity and intermediate pressure to decouple the velocity and pressure calculations in the momentum equation. Specifically, this includes: Calculating the intermediate velocity field that does not satisfy the continuity equation, neglecting the pressure gradient term in the incompressible momentum equation, and substituting the no-slip boundary conditions, we obtain: in, Indicates intermediate speed. Indicates the first Speed ​​at any moment Indicates time progression, Represents the Hamiltonian operator. Indicates kinematic viscosity; Calculate the intermediate pressure field, take the divergence of the intermediate velocity field, and construct the pressure Poisson equation by combining it with the incompressible continuity equation. Adapt it to zero pressure gradient and zero pressure boundary conditions to obtain: in, Indicates intermediate pressure; Calculate the velocity and pressure fields at the next moment, correct the intermediate velocity and pressure fields, and obtain the velocity field at the next moment that satisfies the incompressible continuity equation. and pressure field : in, This indicates the density of the fluid.

10. A high-efficiency analysis system for multi-scale microchannel flow fields using the high-efficiency analysis method for multi-scale microchannel flow fields according to any one of claims 1-9, characterized in that, include: The microchannel flow field solution model is meshed into elements to establish a numerical model of the microchannel flow field. The model is meshed using a multi-level mesh to obtain the node information and element information on the model mesh. The cross-level information transmission unit, in a multi-level mesh, uses the time step of the bottom mesh as a reference to perform time densification on the target area mesh. For the boundary between different levels of mesh, interpolation calculation is used to complete the information transmission between different levels of mesh. The physical parameter extraction unit uses the second-order projection method to solve the incompressible momentum equation, introduces intermediate velocity and intermediate pressure, and then decouples the velocity and pressure calculations in the momentum equation. Extract the unit, perform iterative solution, and after the iteration ends, calculate the flow field value and extract the physical parameters related to the flow field based on the flow field value.

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