A grid generation method for electromagnetic environment simulation on a water surface platform

Abstract

The application discloses a grid generation method for electromagnetic environment simulation on a water surface platform and belongs to the technical field of computational electromagnetics, which comprises the following steps: determining a minimum rectangular area capable of completely covering the shape of a ship platform, and performing segmented function fitting on the outer contour of the ship platform; based on the minimum rectangular area and the segmented outer contour, the number and position coordinates of grid points along the transverse and longitudinal directions of the ship platform are obtained according to a grid division rule, and each grid is indexed by a coordinate number; in the calculation, the grids are called in turn according to the coordinate number, when a certain target grid needs to be used, the position information and area information of the target grid are calculated according to the coordinate number corresponding to the target grid and the grid division rule; and after the current target grid is used up, the grid information of the next coordinate number is covered. The application solves the problem of slow calculation progress or difficulty in calculation caused by the grid generation, storage and calling links in the electromagnetic calculation of a super-electric large-size target.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of computational electromagnetics, and more particularly relates to a grid generation method for electromagnetic environment simulation on a water surface platform. BACKGROUND

[0002] Computational electromagnetics methods can be roughly divided into two categories: full-wave analysis methods and high-frequency methods. Full-wave analysis methods are an accurate calculation method, including Finite-Difference Time-Domain (FDTD), Finite Difference Frequency Domain (FDFD), Finite Element Method (FEM), Method of Moments (MoM), etc. Full-wave analysis methods have a higher requirement for computing resources, but have wide adaptability and can calculate electromagnetic targets with complex structures. High-frequency methods have a relatively low requirement for computing resources, but are only suitable for relatively smooth and flat electromagnetic targets. For electromagnetic environment simulation problems on a water surface platform, a combination of the two types of methods is required, that is, first, a full-wave analysis method is used to calculate the characteristics of a radiation source such as an antenna array with a complex structure, and then a high-frequency method is used to calculate the electromagnetic environment of the super-electric large-size platform under the irradiation of the radiation source. The Physical Optics (PO) method is the most commonly used among many high-frequency methods due to its high computational efficiency and strong adaptability to large targets. The PO method must first model and grid the calculation target, and the grid density and grid quality determine the accuracy of the calculation results, so targeted grid division is required.

[0003] When the electrical size of the calculation target is too large, reaching several thousand wavelengths or even tens of thousands of wavelengths, according to the commonly used grid generation method, the number of grids obtained is too large, resulting in a long grid generation time of tens of hours and a large amount of memory required to store grid information. In the PO method calculation, the vertex coordinates and area information of the grid need to be called, and due to the large number of grids, the calculation progress is extremely slow, and it is difficult to obtain the calculation results. In this scenario, grid generation and storage have become a bottleneck problem that restricts subsequent calculations. SUMMARY

[0004] In view of the above defects or improvement needs of the prior art, the present application provides a grid generation method for electromagnetic environment simulation on a water surface platform, which solves the problem of slow calculation progress or difficulty in calculation caused by the grid generation, storage and calling links in the electromagnetic calculation of super-electric large-size targets.

[0005] To achieve the above purpose, the present application provides a grid generation method for electromagnetic environment simulation on a water surface platform, comprising:

[0006] According to the actual structure of the ship platform, a plane rectangular coordinate system is established on the surface of the ship platform;

[0007] A minimum rectangular area completely covering the shape of the ship platform is determined, and a segmented function fitting is performed on the outer contour of the ship platform;

[0008] A grid division rule is formulated, and the number and position coordinates of the grid points along the transverse and longitudinal directions of the ship platform are obtained according to the grid division rule. Each grid is indexed by a coordinate number, wherein the grid division rule includes the size of the grid and the arrangement mode of the grid;

[0009] In the calculation, the grids are called in sequence according to the coordinate number. When a target grid is needed, the position information and area information of the target grid are calculated according to the coordinate number corresponding to the target grid and the grid division rule;

[0010] After the current target grid is used up, it is covered by the grid information of the next coordinate number.

[0011] In some optional embodiments, when the grid division rule is to perform uniform division on the rectangular grid, DisX = λ / NumDx is used to obtain the initial grid size DisX along the X-axis, and DisY = λ / NumDy is used to obtain the initial grid size DisY along the Y-axis, λ is the wavelength corresponding to the calculation frequency point, NumDx is the number of segments per wavelength along the X-axis, and NumDy is the number of segments per wavelength along the Y-axis.

[0012] In some optional embodiments, NumX = int(Lx / DisX) is used to calculate the number of grids NumX along the X-axis direction, and NumY = int(Ly / DisY) is used to calculate the number of grids NumY along the Y-axis direction, Lx is the length of the rectangle along the X-axis, and Ly is the length of the rectangle along the Y-axis.

[0013] In some optional embodiments, DisX1 = Lx / NumX is used to calculate the final grid size DisX1 along the X-axis, and DisY1 = Ly / NumY is used to calculate the final grid size DisY1 along the Y-axis.

[0014] In some optional embodiments, the center point position coordinates of the grid with coordinate number (i,j) are Sx = (i-0.5)*DisX1, Sy = (j-0.5)*DisY1, the area is DisX1*DisY1, and the values of i are 1, 2, 3, …, NumX in sequence, and the values of j are 1, 2, 3, …, NumY in sequence.

[0015] In some optional embodiments, when the grid is called in sequence according to the coordinate number in the calculation, and a target grid is needed, before the position information and area information of the target grid are calculated according to the coordinate number corresponding to the target grid and the grid division rule, the method further comprises the following steps of:

[0016] According to the hull platform's outer contour function and the position coordinates (Sx, Sy) of the grid center point, it is judged whether the grid with the coordinate number (i, j) falls in the calculation region, if yes, the contribution of the induced current on the grid with the coordinate number (i, j) is calculated, if not, the grid with the coordinate number (i, j) is skipped.

[0017] Overall, compared with the prior art, the above technical scheme conceived by the present application can achieve the following beneficial effects:

[0018] The method uses the outer contour information of the water surface platform to formulate the corresponding division rule, and does not need to generate the grid and store the grid information in advance before the calculation, thereby solving the problem of slow calculation progress or difficulty in calculation caused by the grid generation, storage and calling link in the electromagnetic calculation of the super-electric large-size target. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a water surface platform schematic diagram provided by an embodiment of the present application;

[0020] Figure 2 is a calculation result comparison diagram of 1.5 segments and 5.0 segments per wavelength provided by an embodiment of the present application;

[0021] Figure 3 is a calculation result comparison diagram of 2.0 segments, 2.2 segments and 5.0 segments per wavelength provided by an embodiment of the present application;

[0022] Figure 4 is a calculation result comparison diagram of 2.2 segments per wavelength and commercial software FEKO provided by an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0024] As Figure 1As shown, one embodiment of the present application includes a typical ship platform. For this platform, the electrical size of the ship platform is about 12000 wavelengths x 3200 wavelengths at the center frequency point of calculation. Considering the principle and characteristics of the PO algorithm, the mesh can be uniformly divided into rectangular meshes or triangular meshes. Even if a very low division density is used, for example, 3 segments per wavelength, using the simplest uniform division rule, the number of rectangular meshes obtained is about 345600000, or the number of triangular meshes is about 691200000. If the contour curve in the local area is relatively complex, a larger number of meshes will be generated. The division rule used in this embodiment is to uniformly divide using rectangular meshes. The specific implementation steps are as follows:

[0025] (1) According to the actual structure of the ship platform, a plane rectangular coordinate system is established on the surface of the ship platform, and the longitudinal and transverse directions of the ship platform are respectively taken as the X-axis and Y-axis directions;

[0026] (2) Determine the smallest rectangular area that can completely cover the platform shape, and the length of the rectangle along the X-axis is Lx and the length along the Y-axis is Ly;

[0027] (3) According to the actual structure of the ship platform, the segmented function fitting is performed on the outer contour of the ship platform;

[0028] (4) Calculate the wavelength λ corresponding to the frequency point, set the number of segments per wavelength along the X-axis as NumDx, and the number of segments per wavelength along the Y-axis as NumDy, NumDx and NumDy can take the same value or different values, and the mesh is uniformly divided into rectangular meshes;

[0029] (5) Preliminary calculation of mesh size, the mesh size along the X-axis is DisX = λ / NumDx, and the mesh size along the Y-axis is DisY = λ / NumDy;

[0030] (6) Calculate the number of meshes along the X-axis NumX = int(Lx / DisX) and the number of meshes along the Y-axis NumY = int(Ly / DisY) respectively;

[0031] (7) Calculate the final mesh size along the X-axis DisX1 = Lx / NumX and the mesh size along the Y-axis DisY1 = Ly / NumY;

[0032] (8) In the PO calculation process, the information of each mesh is used in turn according to the two-dimensional coordinate number (ii,jj), ii takes the values 1, 2, 3, …, NumX in turn, and jj takes the values 1, 2, 3, …, NumY in turn;

[0033] The center point position coordinates of the grid numbered by two-dimensional coordinates (ii, jj) are Sx=(ii-0.5)*DisX1, Sy=(jj-0.5)*DisY1, and the area is DisX1*DisY1;

[0034] In the embodiment of the application, the coordinate number can also be represented in one dimension.

[0035] (9) According to the outer contour function of the ship platform and the position coordinates (Sx, Sy) of the grid center point, it is judged whether the grid numbered by two-dimensional coordinates (ii, jj) is in the calculation region, if it is in the calculation region, the contribution of the induced current on the grid is calculated, if it is in the non-calculation region, the grid is skipped.

[0036] The grid size and grid quality determine the accuracy of the calculation result. In order to explore a suitable grid division size, the electric size of this embodiment is reduced by 40 times, and numerical experiments are carried out by using several different grid division sizes. Figure 2 It is the comparison of the calculation results of dividing 1.5 segments and 5.0 segments per wavelength, and it is obvious that the scattering near field calculated by dividing 1.5 segments per wavelength appears oscillation phenomenon and does not converge. Figure 3 It is the comparison of the calculation results of dividing 2.0 segments, 2.2 segments and 5.0 segments per wavelength, and it can be seen that when dividing more than 2.2 segments per wavelength, the convergent result can be obtained. Figure 4 It is the comparison of the calculation results of dividing 2.2 segments per wavelength and the commercial software FEKO, and it can be seen that the grid division strategy can obtain more accurate calculation results than the large panel PO algorithm (LE-PO) in the mature commercial software FEKO.

[0037] It should be noted that according to the needs of implementation, each step / component described in the present application can be split into more steps / components, or two or more steps / components or part of the operation of the steps / components can be combined into a new step / component, to achieve the purpose of the present application.

[0038] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for generating a grid for electromagnetic environment simulation on a water surface platform, characterized in that, The method comprises the following steps: According to the actual structure of the ship platform, a plane rectangular coordinate system is established on the surface of the ship platform; A minimum rectangular area completely covering the shape of the ship platform is determined, and a segmented function fitting is performed on the outer contour of the ship platform; Grid division rules are formulated, and based on the minimum rectangular area and the segmented outer contour, the number and position coordinates of the grid points along the transverse and longitudinal directions of the ship platform are obtained according to the grid division rules, each grid is indexed by coordinate number, wherein the grid division rules include the size of the grid and the arrangement mode of the grid; In the calculation, the grids are called in sequence according to the coordinate number, when a target grid is needed, the position information and area information of the target grid are calculated according to the coordinate number corresponding to the target grid and the grid division rules; After the current target grid is used, it is covered by the grid information of the next coordinate number; Before the step of calling the grids in sequence according to the coordinate number in the calculation, when a target grid is needed, the position information and area information of the target grid are calculated according to the coordinate number corresponding to the target grid and the grid division rules, the method further comprises the following steps: According to the outer contour function of the ship platform and the position coordinates of the grid center points, it is judged whether a target coordinate number grid falls within the calculation area, if it is within the calculation area, the contribution of the induced current on the target coordinate number grid is calculated; if the target coordinate number grid is in the non-calculation area, the target coordinate number grid is skipped.

2. The method of claim 1, wherein, When the grid division rule is a rectangular grid for uniform division, DisX = λ / NumDx is used to obtain the initial grid size DisX along the X-axis, DisY = λ / NumDy is used to obtain the initial grid size DisY along the Y-axis, λ is the wavelength corresponding to the calculation frequency point, NumDx is the number of segments per wavelength along the X-axis, and NumDy is the number of segments per wavelength along the Y-axis.

3. The method of claim 2, wherein, NumX = int(Lx / DisX) is used to calculate the number of grids along the X-axis direction NumX, and NumY = int(Ly / DisY) is used to calculate the number of grids along the Y-axis direction NumY, Lx is the length of the rectangle along the X-axis, and Ly is the length of the rectangle along the Y-axis.

4. The method of claim 3, wherein, DisX1 = Lx / NumX is used to calculate the final grid size DisX1 along the X-axis, and DisY1 = Ly / NumY is used to calculate the final grid size DisY1 along the Y-axis.

5. The method of claim 4, wherein, The center point position coordinates of the grid with coordinate number (i, j) are , , the area is , the value of i is 1, 2, 3, …, NumX in turn, and the value of j is 1, 2, 3, …, NumY in turn.

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