The Research On Finite Volume Time Domain Algorithm In Electromagnetic Scattering

In the increasingly complex shape of the target today,higher accuracy of the electromagnetic simulation is required.The time domain algorithm has the characteristics of small amount of calculation and intuitive time domain information.The most commonly used time domain method is the Finite Difference Time Domain(FDTD)method.By comparing with the traditional cubic mesh of FDTD,the unstructured mesh of the FDTD has more flexibility in describing the complex shape of the target.In addition,the Finite Volume Time Domain developed from Computational Fluid Dynamics can not only draw lessons from the mature time of computational fluid dynamics,the high order discrete format of space,and the display of numerical results,but also can realize the coupling solution of electromagnetics and hydrodynamics.From this point of view,we developed a program of Finite Volume Time Domain(FVTD)method to solve the related problems in electromagnetic scattering.The main research contents are organized as follows:This paper firstly describes the basic principle of Finite Volume Time Domain and then deduces the Steger-Warming flux splitting method which is suitable for solving the unified form Maxwell equations,the spatial discrete MUSCL interpolation method,the Gauss-Green method,as well as the Runge-Kutta method that illustrates the explicit time iteration.The processing methods of boundary conditions in simulation calculation,time-domain and frequency-domain transform methods in the post-processing steps,near-and-far field transform methods,and the related concepts and formulas of radar cross-sections are also given.Furthermore,propagation problems of electromagnetic wave in one-layer and two-layer media are simulated based on one-dimensional Finite Volume Time Domain method.Discussion and analysis on the influences of grid density,interpolation format and stability factor on the propagation accuracy of electromagnetic waves were also conducted.The comparison with the analytical solution shows that the method is feasible.Finally,with the aim to tackle the incresingly complex shape of the target,we developed the two-dimensional and three-dimensional Finite Volume Time Domain method which are both based on the unstructured grid technology.The precision of these methods is verified by the electromagnetic scattering of an infinite conductor cylinder and the conductor ball.The two methods are further applied to the electromagnetic scattering of the infinite square cylinder,two-dimensional airfoil structure,two-dimensional flat plane,cube and inlet model.The numerical results are consistent with the findings of the cited references,which shows that the unstructured grid algorithm can be well applied to the electromagnetic simulation of objects with arbitary shape structure.