Large Scale Parallel FDTD For Electromagnetic Coupling To Cavities

The finite difference time domain (FDTD) method has been demonstrated to be powerful and versatile for modeling complex electromagnetic problems and massively parallel computation. The electromagnetic coupling into cavities is a very essential issue in electromagnetic compatibility and electromagnetic interference. In this thesis, a large scale parallel FDTD program based on the JASMIN (J parallel Adaptive Structured Mesh applications Infrastructure) framework is proposed to study this problem. The main contents of this thesis can be summarized as follows:the design and implementation of large-scale parallel FDTD program on JASMIN; CAD-based cartesian mesh dissection technique and its parallelization for FDTD; electromagnetic oupling studies on complex cavities; an improved near-to near (far) zone transformation based on Kirchhoff integral in FDTD simulation.JASMIN is developed by Beijing Institute of Applied Physics and Computational Mathematics. In this thesis, a parallel FDTD program is designed and implemented on JASMIN. By means of encapsulating high performance data structure, integrating numerical methods, masking the parallelization and adaptive meshing technology, JASMIN accelerates the development of parallel programs which can employ modern HPC (High Performance Computer) efficiently. This parallel FDTD program is initial-functional with FDTD iteration, excitation, CPML (Convolutional Perfect Matched Layer) absorption boundary condition, automatic load balance, etc., and is verified by computing the radiation fields of an electric dipole. And the parallel performance test indicates that a high parallel efficiency is obtained.However, a complex geometry has to be discretized first in an application of FDTD. Especially for massively parallel FDTD, it is very important to build meshes in an efficient way. In this paper, a fast and highly accurate Cartesian mesh generation technique based on the triangle-facet CAD data files for FDTD is presented. Its high-efficiency parallelization is based on JASMIN. This parallelization implementation program structure is very useful to obtain Yee-grids for massively parallel FDTD. The numerical examples show that this parallel mesh generation technique can accurately, fast and efficiently solve complex objects constituted by a lot of various medium solids. In addition, a cross-platform software interface based on QT and OpenGL for pretreatment of FDTD in order to improve the mesh generation algorithm and make the simulation program more practical. With this platform, STL format CAD file can be displayed and modified, while some simple entity can be edited and exported to STL data. The large-scale parallel FDTD and CAD-based cartesian mesh dissection technique on JASMIN can be composed to a typical FDTD solver. Above-mentioned solver is very useful to solve electromagnetic coupling to complex objects. A large number of numerical examples are given. The results computed by parallel FDTD are compared with commercial electromagnetics simulation package. The capability and precision of the large-scale parallel FDTD solver can be demonstrated. Then a computer case in industry is computed on MPP with 250 processor cores. Finally, computer with a lumped element microstrip circuit board is analyzed.The improved rapid time-domain near-near (far) zone transformation on FDTD calculations is used to obtain far-field information of electromagnetic radiation, scattering and electromagnetic leakage calculation. In order to minimize the calculation data for far-field transforming, the data on equivalent surface are sampled in space-domain or time-domain, which saves the computing time consumedly. Its parallelization is implemented on JASMIN. Examples, that is, electric dipole radiation, sphere scattering and cavity radiation are given.