JASMIN框架论文：机箱电磁耦合问题的大规模并行FDTD实现.doc

JASMIN框架论文：机箱电磁耦合问题的大规模并行FDTD实现【中文摘要】时域有限差分法(FDTD)是一种有效的电磁场数值求解方法。其简单、灵活且易于并行,现已被广泛应用于各种复杂的电磁仿真分析。本文主要致力于适于大规模并行FDTD及其实用中的关键技术研究,并以机箱的电磁耦合为背景展开。研究的主要内容包括：JASMIN框架下的大规模并行FDTD实现研究；适于大规模并行时域有限差分法的网格剖分算法研究；基于大规模并行FDTD的复杂电磁耦合问题研究；基于空域-时域抽样的基尔霍夫近-近(远)场转换算法及其并行化研究。JASMIN框架是由北京应用物理与计算数学研究所研制的并行框架,全称为并行自适应网格应用支撑软件框架(J parallel Adaptive Structured Mesh applications Infrastructure)。本文首先在JASMIN框架上完成了高效、高置信度的大规模并行FDTD基本计算程序,包括FDTD迭代、CPML吸收边界、点源激励以及自动负载平衡和重启动等等,并以自由空间电偶极子辐射问题为例完成了程序计算精度和有效性的验证。采用FDTD仿真电磁问题,首先需要对目标进行网格化离散建模。在大规模并行FDTD计算中,高效的网格生成算法更为必要。为了适应大规模并行FDTD电磁建模网格剖分需求,本文讨论了一种基于三角面元CAD(Computer-aided design)数据文件的FDTD网格自动剖分方法,并在JASMIN下完成了该算法的并行化。数值算例表明这是一种准确、快速的自动网格生成技术,有效的解决了大规模并行FDTD的网格化离散建模问题。此外,为了能完善网格剖分算法,也为了使得仿真模块更具实用性,本文还介绍基于QT与OpenGL的可视化界面开发技术,在此基础上实现了跨平台的FDTD前处理软件界面,该平台能够对STL格式CAD文件的显示和修改,同时能够编辑一些简单的实体图形并导出STL文件。以上述两条为基础研究了复杂机箱的电磁耦合问题,通过大量电磁耦合的算例计算,并将结果与商业软件对比,验证了并行FDTD在研究大规模复杂电磁耦合问题中的准确性和可行性。然后采用250个处理器核计算了已经应用于实际的金河田兼容机机箱的耦合效应,最后还分析了带集总参数元件微带电路板电路的机箱的耦合效应。对于大规模并行,若要通过近-近(远)变换求得多个点的场强时,计算量较大,可采用时域-空域抽样减小计算量。本文提出了一种改进的近-近(远)场变换,其以Kirchhoff积分近-近(远)变换为基本原理,采用抽样方法实现快速的近-近(远)场变换。改进近-近(远)场变换算法的并行化的是在JASMIN框架下实现的,本文详细介绍了其实现的过程,采用电偶极子辐射、球体散射以及单缝腔体辐射为算例,验证了方法的正确性和高效性,为大规模并行FDTD在研究电磁辐射与散射以及电磁泄漏问题时需要获得计算区域外的场值提供了算法支持。【英文摘要】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.【关键词】JASMIN框架 时域有限差分法 大规模并行 网格剖分 改进近-近(远)变换 电磁耦合【英文关键词】JASMIN FDTD Large scale parallelization Mesh Dissection Technique Improved near -to -near (far) zone transformation Electromagnetic coupling【目录】机箱电磁耦合问题的大规模并行FDTD实现摘要6-7Abstract7-8第1章 绪论11-171.1 研究背景11-131.2 国内外研究现状13-151.3 本文的主要研究内容及论文结构15-17第2章 基于JASMIN框架结构的并行FDTD17-262.1 FDTD基本原理17-192.1.1 FDTD方程17-182.1.2 数值稳定和数值色散18-192.1.3 吸收边界192.2 JASMIN框架19-222.2.1 简介19-202.