Study On Numerical Calculation Method Of Mixed FDTD And Its Application

In recent years,with the rapid development of high performance computing hardware facilities in China,large-scene high-performance electromagnetic numerical computation has become an important research method of complex electromagnetic environment,and its application prospect is very wide.Finite-Difference Time-Domain method(FDTD)has been paid more and more attention because of its simple,intuitive and easy to parallel implementation.It is of great theoretical and practical significance to study the related techniques of FDTD numerical computation.Based on the actual research project of the Electromagnetic Environment Effect Research Institute of Railway University in Shijiazhuang,this paper studies preprocess,numerical calculation,post processing etc,the main work is as follows:(1)Adaptive FDTD Conformal Grid TechnologyIn order to reduce the error caused by the model partition,the conformal Yee mesh generation technology of the target model is discussed and realized.By using the GID software to divide the target model to obtain the triangular data file,based on which,the principle of "projection intersection method" and area comparison method to generate Yee grid is compared.Yee grids were generated based on the area comparison method easier to understand,based on which all kinds of situation of conformal face are studied in detail.Each case is managed,and according to the normal direction to realize medium area fill,finally using c++ language to achieve the adaptive conformal grid generation technique of complex model,provides a precise and effective model for FDTD simulation below.(2)FDTD programming based on GiDFDTD programming has secondary development based on GiD.In order to study the influence of lightning on the electromagnetic environment of high-speed railway,based on the GID,excitation source model setting of thunder and lightning is added,and the programming of core computing program was realized by using C++ language,the result extraction studied,and the visualization function of electromagnetic field intensity and the near field 3d results is realized.The integration of other functions of the original software forms a new simulation software,which provides a prototype system for simulating the electromagnetic environment of high-speed railway.(3)Simulation of High-speed Railway Electromagnetic Environment Based on FDTD ProgramBased on the software above,the electromagnetic pulse effect of the car body of high speed railway is simulated.The process of related model creation and the setting of parameters are introduced in detail,and a conformal mesh partition for compartment model is completed.The near and far field of the simulation results are analyzed,which verifies the accuracy of conformal grid technology and the correctness of the program design.