基于非结构网格格点FVTD算法的电磁散射模拟

Electromagnetic Scattering Simulation Based on Cell-Vertex Unstructured-Grid FVTD Algorithm

为了利用格点数值模拟复杂外形的电磁散射场,研究了基于非结构网格格点的时域有限体积算法。该算法借鉴计算流体力学的做法,采用Steger-Warming通量分裂和近似黎曼解两种方法处理通量运算,采用四步Runge-Kutta格式进行时间推进求解。本文用发展的算法数值模拟了包括鼓包、舱体以及外挂干扰的复杂外形电磁散射场,并给出了对应的雷达散射截面。算例表明:两种通量运算计算得到的双站雷达散射截面结果一致,且计算效率相当;舱体、鼓包以及外挂对飞行器主体的电磁散射特性均有影响,其中外挂对主体干扰尤为明显。由于采用了基于非结构网格格点的算法,特别适合处理多体干扰等复杂情形。

In order to use grid points for simulating the scattered electromagnetic fields with complicated geometries, a finite-volume time-domain algorithm based on cell-vertex of the unstructured grids is studied. Referring to the approach used in computational fluid dynamics, both Steger-Warming flux vec- tor splitting and approximate Riemann solver are introduced in dealing with the computation of flux re- lated to the governing equations, and an explicit four-stage Runge-Kutta scheme is employed in time dis- cretization. By using the developed algorithm, scattered fields and bistatic radar cross section are calcu- lated for complicated cases of aerodynamic shapes with cavity, external obstacle or an external store. Numerical examples show that both the bistatic radar cross section and the computational efficiency are nearly the same by using either Steger-Warming flux vector splitting or approximate Riemann solver. The results also show that the scattered characteristics of the main aerodynamic shapes with or without cavity, external obstacle or an external store are obviously different, particularly for the case of aerody- namic shapes with an external store. Additionally, the presented method has the ability to accommodate more complicated geometries due to the use of cell vertex of the unstructured grids.