Electromagnetic wave reflected from a moving body through use of the body fitted grid generation with moving boundary

运动或旋转物体的电磁散射研究是运动物体电磁探测中的一个重要问题。这些问题已调查分析的洛伦兹变换。然而，当散射体形状和振动是任意的时，这种方法很难用于分析一般情况。由于需要更多关于微波与运动物体相互作用的详细信息，因此有必要数值求解这些问题。数值网格生成是分析任意形状区域有限差分法的一种方便方法。本文提出了一种新的坐标线与任意形状动边界重合的网格生成方法及其应用。我们将网格生成扩展到包含时间分量的区域。将物理区域中与动边界轮廓线重合的时间相关曲线坐标系变换到计算区域中的固定直角坐标系。利用所提出的变换技术，可以在固定的直角坐标系中很容易地求解偏微分方程。最后，我们可以在一个固定的直角坐标系中解决运动问题。在简单变换中，可以在物理区域和计算区域之间选择函数。我们已经把这种技术应用于电磁问题。我们把这种方法用于一个准定常场。利用该技术，分析了平行理想导体运动平板间的电磁波反射和运动物体在任意方向上的电磁散射。一些数值结果进行了比较，精确的，它们之间得到了很好的协议。

The study of electromagnetic scattering by a moving or a rotating body is an important problem for electromagnetic probing of moving body. These problems have been investigated analytically by a Lorentz transformation. However, it is difficult to apply this method to analyze general cases, when scatter shape and vibration are arbitrary. As more detailed information is required concerning microwave interactions with moving bodies, it is necessary to solve these problems numerically. Numerical grid generation is a convenient method to analyze finite difference method on an arbitrary shaped region. We have proposed a novel numerical procedure of grid generation having coordinate line coincident with an arbitrarily shaped moving boundary and applied method. We expanded grid generation into a region including time component. The time dependent curvilinear coordinate system which coincides with a contour of moving boundary in a physical region is transformed into the fixed rectangular coordinate system in a computational region. By using the presented transformation technique, partial differential equations can be solved very easily in the fixed rectangular coordinate system. Finally, we can solve the moving problem in a fixed rectangular coordinate system. In the simple transformation, it is possible to choose the function between the physical region and the computational region. We have applied this technique to the electromagnetic problem. We are treating this method for a quasi-stationary field. With this technique, electromagnetic waves reflected between the parallel perfectly conducting moving plate and electromagnetic scattering from a moving body in an arbitrary direction are analyzed. Some numerical results are compared with the exact ones and excellent agreement between them is obtained.