Nested grid generation method for rapid simulation of electromagnetic-thermal-force multi-physics field

Abstract

The invention discloses a nested grid generation method for rapid simulation of an electromagnetic-thermal-force multi-physical field, and mainly solves the problem that the simulation efficiency is affected due to the fact that the same set of grid is adopted in electromagnetic-thermal-force multi-physical simulation to generate calculation. Comprising the following steps: 1) subdividing to obtain initial coarse grid units; 2) taking a midpoint of each edge in the initial coarse grid unit, connecting the midpoints to obtain a sub-tetrahedron at the vertex of the initial coarse grid unit, and cutting off the sub-tetrahedron to obtain an octahedron; (3) segmenting the octahedron by taking two parallelograms formed inside the octahedron as tangent planes to obtain segmented sub-tetrahedrons; (4) the refinement operation is repeatedly executed for a preset number of times, and a dense grid is obtained; and 6) carrying out electromagnetic simulation by adopting a dense grid, and carrying out heat and force simulation by utilizing an initial coarse grid and a finite element method to complete multi-physical field simulation. According to the method, the calculation amount of heat and force simulation can be saved, and the efficiency of electromagnetic-heat-force multi-physical field simulation is effectively improved while the simulation precision is not influenced.

Description

Technical Field

[0001] The present invention belongs to the field of electrical technology and further relates to computational electromagnetics. Specifically, it is a nested grid generation method for rapid simulation of electromagnetic-thermal-mechanical multi-physics fields. The method can be used to improve the efficiency of electromagnetic-thermal-mechanical multi-physics field simulation and promote the application of multi-physics field simulation technology in wireless communications, integrated circuits, microwave circuits, antenna design, precision guidance and other fields. Background Art

[0002] In the fields of wireless communication, integrated circuits, microwave circuits, antenna design, precision guidance, etc., with electromagnetic fields as the center, the coupling problems of multiple physical fields such as electromagnetic fields, temperature fields, and stress fields are becoming more and more prominent. The actual measurement of the above electromagnetic-thermal-force multi-physical field coupling problems has the disadvantages of high cost, long cycle, and the results are easily affected by the test environment. Therefore, electromagnetic-thermal-force multi-physics simulation technology has become a necessary means to study the effects of multiple physical fields. At present, the mainstream electromagnetic-thermal-force multi-physics field simulation methods are usually based on finite element algorithms, that is, electromagnetic simulation, thermal simulation, and force simulation all use finite element algorithms. During simulation, the geometric model of the simulation object needs to be meshed first. The commonly used mesh unit form is tetrahedral mesh. Electromagnetic simulation, thermal simulation, and force simulation usually use the same set of tetrahedral meshes.

[0003] Since the electromagnetic field changes much faster than the heat and force, the actual mesh unit sizes required for electromagnetic, thermal, and force simulations are different. The mesh size required for electromagnetic simulation is much smaller than that for thermal and force simulations. In order to ensure the simulation accuracy, the current mainstream electromagnetic-thermal-force multi-physics field simulation method uniformly uses the dense mesh required for electromagnetic simulation. However, this mesh division method will bring a large amount of unnecessary calculations to thermal and force simulations, affecting the simulation efficiency. Therefore, it is urgent to study a mesh technology that can be applied to different simulation requirements in multi-physics fields. Summary of the invention

[0004] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and propose a nested grid generation method for rapid simulation of electromagnetic-thermal-force multi-physics fields, which mainly solves the problem that the same set of grids are used to generate extra calculations in electromagnetic-thermal-force multi-physics simulations, affecting the simulation efficiency. The present invention designs a new nested grid division method for segmenting the geometric model of the simulation object based on the physical field characteristics of electromagnetic simulation and thermal and force simulations themselves. The dense grid in the nested grid is used in electromagnetic simulation, and the coarse grid in the nested grid is used in thermal and force simulations, thereby saving the calculation amount of thermal and force simulations, and effectively improving the efficiency of electromagnetic-thermal-force multi-physics field simulations without affecting the simulation accuracy.

[0005] The present invention achieves the above-mentioned purpose by the following specific steps:

[0006] (1) Setting the initial coarse grid size, dividing the geometric model of the simulation object according to the size, and obtaining the initial coarse grid unit;

[0007] (2) Take the midpoint of each edge in the initial coarse grid unit, and then connect the midpoints in the same triangular face with a straight line to obtain four sub-tetrahedrons with similar shapes to the initial coarse grid unit and located at the vertices of the initial coarse grid unit, denoted as T1, T2, T3, and T4;

[0008] (3) The sub-tetrahedrons T1, T2, T3, and T4 located at the vertices of the initial coarse mesh unit are trimmed off to obtain the octahedron retained inside;

[0009] (4) The octahedron is divided using the two parallelograms formed inside as the cutting planes to obtain four sub-tetrahedrons after the octahedron is divided, which are recorded as T5, T6, T7, and T8;

[0010] (5) Performing steps (2) to (4) on each initial coarse mesh unit to obtain eight tetrahedrons T1 to T8, that is, achieving one refinement of the entire initial coarse mesh. The number of refinements is set according to the actual needs of electromagnetic simulation, and the same operation as the refinement of the initial coarse mesh unit is performed again on the mesh after the previous refinement until the preset number of refinements is reached to obtain a dense mesh;

[0011] (6) Use dense grids to perform electromagnetic simulation and obtain the electric field distribution;

[0012] (7) Find the dense grid unit where the coarse grid node is located. After performing electromagnetic simulation, use the electric field strength E at the vertex of the dense grid unit to calculate the conductor loss P at the vertex position of the coarse grid. c and dielectric loss P d , P c +P d As the heat source at the vertex position of the coarse grid, the initial coarse grid and the finite element method are then used to perform thermal and force simulation to achieve electromagnetic-thermal-force multi-physics simulation.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] First, since the present invention takes into account that the grid unit sizes actually required for simulations of different physical fields such as electromagnetic, thermal, and force are not the same, nested grids of different grid sizes are designed for multi-physical field simulations on the premise of comprehensively considering the characteristics of electromagnetic, thermal, and force themselves, to ensure that electromagnetic simulation and thermal and force simulation can respectively use grids of appropriate density, that is, electromagnetic simulation uses dense grids, and thermal and force simulation uses coarse grids; thereby saving the amount of calculation for thermal and force simulations, and effectively improving the efficiency of electromagnetic-thermal-force multi-physical field simulations as a whole without affecting the simulation accuracy.

[0015] Second, since the dense grid for electromagnetic simulation and the coarse grid for thermal and force simulation designed in the present invention are nested with each other, the vertices of the coarse grid overlap with some vertices of the dense grid, so information can be transferred between the electromagnetic simulation and the thermal simulation; after the electromagnetic simulation, the heat source at the coarse grid vertex position can be obtained by calculating the electric field strength of the dense grid unit vertex where the coarse grid node is located, and the coarse grid and the finite element method are used to perform thermal and force simulation, thereby realizing electromagnetic-thermal-force multi-physics simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram of the initial coarse grid unit;

[0017] Figure 2 This is a schematic diagram of the result obtained by taking the midpoints of the edges of the initial coarse grid unit and connecting them in the present invention;

[0018] Figure 3 Schematic diagram of the octahedron retained inside the initial coarse grid unit after removing four sub-tetrahedrons T1, T2, T3, and T4 in the present invention;

[0019] Figure 4 Schematic diagrams of two division situations of dividing the octahedron inside the parallelogram in the present invention;

[0020] Figure 5 A schematic diagram of a nested grid for electromagnetic simulation and thermal and force simulation generated using the method of the present invention;

[0021] Figure 6 This is a schematic structural diagram of a high-power microwave irradiation filter in an embodiment of the present invention;

[0022] Figure 7 The present invention is a temperature distribution diagram of the filter surface at 10ns in an embodiment; wherein (a) is the temperature distribution of the filter surface at 10ns obtained by using the method of the present invention, and (b) is the temperature distribution of the filter surface at 10ns obtained without using the method of the present invention;

[0023] Figure 8 The present invention is a displacement distribution diagram of the filter surface in the embodiment; wherein (a) is the displacement distribution of the filter surface obtained by using the method of the present invention, and (b) is the displacement distribution of the filter surface obtained without using the method of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0025] Example 1: Reference Figure 1 The present invention proposes a nested grid generation method for rapid simulation of electromagnetic-thermal-mechanical multi-physics fields, and the implementation steps are as follows:

[0026] Step 1. Set the initial coarse grid size, divide the geometric model of the simulation object according to the size, and obtain the initial coarse grid unit; the initial coarse grid size is 1-3 times the wavelength.

[0027] Step 2. Take the midpoints of the edges in the initial coarse grid unit, and then connect the midpoints in the same triangular face with straight lines to obtain four sub-tetrahedrons located at the vertices of the initial coarse grid unit with similar shapes to the initial coarse grid unit, which are recorded as T1, T2, T3, and T4;

[0028] Step 3. Cut off the sub-tetrahedrons T1, T2, T3 and T4 located at the vertices of the initial coarse mesh unit to obtain the octahedron retained inside;

[0029] Step 4. Split the octahedron using the two parallelograms formed inside the octahedron as sections. Specifically, split the octahedron using any two perpendicularly intersecting parallelograms formed inside the octahedron as sections to obtain four sub-tetrahedrons after the octahedron is split, which are recorded as T5, T6, T7, and T8.

[0030] Step 5. Perform steps (2)-(4) on each initial coarse mesh unit to obtain 8 tetrahedrons T1-T8, that is, to achieve a refinement of the entire initial coarse mesh. Set the number of refinements according to the actual needs of electromagnetic simulation, and perform the same operation as the refinement of the initial coarse mesh unit on the mesh after the previous refinement until a preset number of refinements is reached to obtain a dense mesh. The number of refinements is set according to the actual needs of electromagnetic simulation. After performing the preset number of refinement operations, the mesh size can be reduced to 0.1 times the wavelength to meet the requirements of electromagnetic simulation.

[0031] The dense grid is specifically obtained by performing steps 2-4 on the initial coarse grid unit to obtain a first fine grid, treating the first fine grid as the initial coarse grid and performing steps 2-4 again to obtain a second fine grid, and then treating the second fine grid as the initial coarse grid and performing steps 2-4 again to obtain a third fine grid, and so on, to obtain a dense grid that can meet the electromagnetic simulation requirements after completing the preset number of refinements.

[0032] Step 6. Use a dense grid to perform electromagnetic simulation and obtain the electric field distribution;

[0033] Step 7. Find the dense grid unit where the coarse grid node is located. After performing electromagnetic simulation, use the electric field strength E at the vertex of the dense grid unit to calculate the conductor loss P at the vertex position of the coarse grid. c and dielectric loss P d , P c +P dAs the heat source at the vertex position of the coarse grid, the initial coarse grid and the finite element method are then used to perform thermal and force simulation to achieve electromagnetic-thermal-force multi-physics simulation.

[0034] The conductor loss P at the vertex position of the coarse grid c and dielectric loss P d , calculated according to the following formula:

[0035] P c =σ|E| 2 ,

[0036]

[0037] Where σ is the conductivity, D is the electric displacement vector, D = εE, ε represents the dielectric constant, and t is the time variable.

[0038] Embodiment 2: The overall implementation steps of the present invention are the same as those of Embodiment 1. Figure 1-5 Specific examples are given to further describe the implementation process of the present invention in detail:

[0039] Step 1) First, the geometric model of the simulation object is initially coarsely meshed. The initial coarse mesh size is preferably 1 times the wavelength in this embodiment. Figure 1 An initial coarse mesh element is shown.

[0040] Step 2) Figure 2 As shown, first take the midpoints of each edge of the initial coarse grid unit, and then connect the midpoints in the same triangular face with straight lines, so that four similar sub-tetrahedrons will be obtained at the vertices of the initial coarse grid unit. These four sub-tetrahedrons are recorded as T1, T2, T3, and T4.

[0041] Step 3) Figure 3 As shown, the four sub-tetrahedrons T1, T2, T3, and T4 in the initial coarse grid unit are cut off to obtain the octahedron retained inside.

[0042] Step 4) For the inner octahedron, follow Figure 4 The two parallelograms shown in the middle shadow divide the internal octahedron to obtain another four sub-tetrahedrons T5, T6, T7, and T8;

[0043] Step 5) Through steps 1) to 4), the initial coarse grid unit can be refined into 8 sub-tetrahedrons T1, T2, T3, T4, T5, T6, T7, and T8, wherein T1, T2, T3, and T4 are sub-tetrahedrons located at the vertices of the initial coarse grid unit, and T5, T6, T7, and T8 are sub-tetrahedrons divided from the internal octahedron; performing the above operation on each coarse grid unit can achieve a refinement of the entire initial coarse grid, and the above operation can be performed again on the refined grid to achieve further refinement of the refined grid. In the electromagnetic-thermal-mechanical multi-physics field simulation, this embodiment preferably refines the initial coarse grid 3-4 times.

[0044] Step 6) Figure 5 As shown in the figure, taking the two-dimensional case as an example, the nested grids of electromagnetic simulation and thermal and force simulation obtained through the above grid refinement process are displayed. In the two-dimensional case, the tetrahedral grid units degenerate into triangular grid units; the circles in the figure represent coarse grid vertices, and the solid points represent dense grid vertices. In the electromagnetic-thermal-force multi-physics field simulation, the electromagnetic simulation uses a dense grid, and the thermal and force simulations use a coarse grid.

[0045] Step 7) During electromagnetic-thermal-force multi-physics simulation, electromagnetic loss will cause heat, so information needs to be transferred between electromagnetic simulation and thermal simulation. In the present invention, the dense grid of electromagnetic simulation and the coarse grid of thermal and force simulation are nested with each other, such as Figure 5 As shown in the figure, since the coarse mesh vertices used in thermal simulation must overlap with some vertices of the dense mesh used in electromagnetic simulation, we can first find the dense mesh unit where the coarse mesh node is located. After the electromagnetic simulation, the conductor loss P at the coarse mesh vertex position is calculated according to the electric field strength E of the dense mesh unit vertex. c and dielectric loss P d :

[0046] P c =σ|E| 2 ,

[0047]

[0048] Where σ is the conductivity, D is the electric displacement vector, D = εE, ε represents the dielectric constant, and t is the time variable. Then P c +P d It serves as the heat source at the vertex position of the coarse grid. Then, just like the traditional thermal and force simulation, the electromagnetic-thermal-force multi-physics simulation can be realized by using the coarse grid and the finite element method for thermal and force simulation.

[0049] The effect of the present invention is further described below in conjunction with simulation experiments.

[0050] In this experiment, the nested grid technology for rapid simulation of electromagnetic-thermal-mechanical multi-physics fields proposed by the present invention is used and not used. Figure 6 The electromagnetic-thermal-mechanical multi-physics field simulation is performed on the high-power microwave irradiation filter structure problem shown, and the calculation time of the two is compared to verify the effectiveness of the present invention.

[0051] In this example, the high-power microwave irradiation direction is along the -z direction, the polarization direction is the +x direction, the amplitude is 1MV / m, and the frequency is 4GHz. Figure 7 (a) and (b) in the figure respectively show the temperature distribution of the filter surface at 10ns obtained by using and not using the method of the present invention, and the two are completely consistent. Figure 8 (a) and (b) in the figure respectively show the displacement distribution of the filter surface obtained by and without the method of the present invention, and the two are completely consistent. It can be seen that the method of the present invention does not affect the simulation accuracy. In addition, the calculation time of the present invention in this example is 9800 seconds, while the calculation time without the present invention is 13523 seconds, which effectively proves that the present invention can effectively improve the efficiency of electromagnetic-thermal-mechanical multi-physics field simulation.

[0052] Parts of the present invention that are not described in detail belong to common knowledge among those skilled in the art.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It is obvious that for professionals in this field, after understanding the content and principles of the present invention, they may make various modifications and changes in form and details without departing from the principles and structures of the present invention. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A nested grid generation method for rapid simulation of electromagnetic-thermal-mechanical multi-physics fields, characterized in that: The steps include: (1) Setting the initial coarse grid size, dividing the geometric model of the simulation object according to the size, and obtaining the initial coarse grid unit; (2) Take the midpoint of each edge in the initial coarse grid unit, and then connect the midpoints in the same triangular face with a straight line to obtain four sub-tetrahedrons with similar shapes to the initial coarse grid unit and located at the vertices of the initial coarse grid unit, denoted as T1, T2, T3, and T4; (3) The sub-tetrahedrons T1, T2, T3, and T4 located at the vertices of the initial coarse mesh unit are trimmed off to obtain the octahedron retained inside; (4) The octahedron is divided using the two parallelograms formed inside as the cutting planes to obtain four sub-tetrahedrons after the octahedron is divided, which are recorded as T5, T6, T7, and T8; (5) Performing steps (2) to (4) on each initial coarse mesh unit to obtain eight tetrahedrons T1 to T8, that is, achieving one refinement of the entire initial coarse mesh. The number of refinements is set according to the actual needs of electromagnetic simulation, and the same operation as the refinement of the initial coarse mesh unit is performed again on the mesh after the previous refinement until the preset number of refinements is reached to obtain a dense mesh; (6) Use dense grids to perform electromagnetic simulation and obtain the electric field distribution; (7) Find the dense grid unit where the coarse grid node is located. After performing electromagnetic simulation, use the electric field strength E at the vertex of the dense grid unit to calculate the conductor loss P at the vertex position of the coarse grid. c and dielectric loss P d , P c +P d As the heat source at the vertex position of the coarse grid, the initial coarse grid and the finite element method are then used to perform thermal and force simulation to achieve electromagnetic-thermal-force multi-physics simulation.

2. The method according to claim 1, characterized in that: The initial coarse grid size in step (2) is 1-3 times the wavelength.

3. The method according to claim 1, characterized in that: Step (4) of dividing the octahedron using two parallelograms formed inside the octahedron as cut planes specifically refers to dividing the octahedron using any two perpendicularly intersecting parallelograms formed inside the octahedron as cut planes.

4. The method according to claim 1, characterized in that: In step (5), the number of refinements is set according to the actual requirements of the electromagnetic simulation, so that the size of the refined grid is reduced to 0.1 times the wavelength to meet the requirements of the electromagnetic simulation.

5. The method according to claim 1, characterized in that: The dense grid in step (5) is specifically obtained by executing steps (2) to (4) on the initial coarse grid unit to obtain a first fine grid, treating the first fine grid as the initial coarse grid and executing steps (2) to (4) again to obtain a second fine grid, and then treating the second fine grid as the initial coarse grid and executing steps (2) to (4) again to obtain a third fine grid, and so on, after completing the preset number of refinements.

6. The method according to claim 1, characterized in that: The conductor loss P at the vertex position of the coarse grid in step (7) is c and dielectric loss P d , calculated according to the following formula: P c =σE 2 , Where σ is the conductivity, D is the electric displacement vector, D = εE, ε represents the dielectric constant, and t is the time variable.

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