Study On Parallel FDTD Algorithm And Its Applications On PC And Blade Server Clusters

With the rapid development of modern electronic technology, the problems of electromagnetics engineering becomes more and more complex, so that the existing system of computational electromagnetics based on one processor can't satisfy the need of engineering. And synchronously, the hardware of computers has been developing rapidly. The processors with cores and blade servers become more and more popular. The studying of parallelization algorithms of computational electromagnetics can exert the advantages of the computer hardware fully, so improve the capacity for analyzing electromagnetic for targets in complicated EM environments. As one of the most important methods in electromagnetic numerical simulations, the finite-difference time-domain (FDTD) method has own unique advantages and can be used to solve many engineering problems. In this thesis, based on PC and blade clusters, several key techniques of the parallel FDTD method and their applications in electromagnetic problems are studied in depth and detail, the work of the author is mainly focused on:(1). MPI-based Parallel FDTD method on the PC cluster is realized by subdividing the whole FDTD computation space into several sub-domains and transferring field values across the interfaces between the neighboring processes with three field communication patterns. Then the computation flow of the Parallel FDTD method is presented and a high performance PC cluster is set up. Lastly, the general rules are proposed on how to obtain the highest efficiency of Parallel FDTD algorithm by optimizing MPI virtual topology through solving a typical problem.(2). To avoid the error with the staircase approximation on slick curved surface, a modified conformal FDTD scheme is introduced through two traditional integral around the contour path following the edges of the distorted cell and its entirety. Combined with Parallel FDTD, the scheme are used to analyze an example and it prove the validities. Then the algorithm is also used for PBG filters. Then the algorithm is mixed with the isolation theory and canonical parts are modeled in the conformal scheme. Then electromagnetic compatibility (EMC) of complex and electrically large targets is analyzed. Based on this, The effective permittivity and electric conductivity for electric field samples on the cells are proposed for solving the scattering of electrically large thin-coated targets. (3). A nodel mechanism to analyze the shielding effectiveness of the metallic cavities with apertures is firstly presented in this paper. The problem belongs to harmonic phenomena, so a long time is needed when the sampling electric field converges. Then The sampling electric field in cavity is dealt with Windowing technique, which can reduce the total time steps greatly. However, it is still a problem at which time step the time-domain data should be windowed. Controlling Factor, which can choose a proper time step to execute the Windowing, is firstly presented to obtain the correct SE curve. Furthermore, the mechanism is applied to compute the corresponding SE of the enclosure with apertures of shape, position and number. Some useful conclusions to the practical electromagnetic shielding problems are obtained.(4). Coupling considered, analyzing the phased arrays is difficult. Parallel FDTD, as a full-wave numerical method, can analyze the problem accurately. From the classic array theory, the phase of driving sources can be determined according to main-beam direction, and then the method that driving sources are added in FDTD method is obtained. Electric dipole array and a microstrip phased array are analyzed to prove the validities. Then the radiation of a large microstrip phased array mounted on a helicopter is analyzed. Further, FDTD-UTD algorithm is presented to analyze phased array antennas mounted on airborne platform. Firstly, the parallel FDTD method is utilized to find the field vector component of the phased array antennas, and then these vector components are employed as the source of the UTD method to obtain the disturbed radiation pattern.(5).Parallel FDTD algorithm is transplanted into HP ProLiant BL460c blade server that belongs to National Key Laboratory of Microwave and Antennas Technology in China. Architecture, software and hardware configuration of blade server are instructed in order. There are so many computing nodes that the structure of communication is complicated. In order to make full use of the performance of the parallel FDTD method based on the blade serve, the radiation patterns in the far field of two ultra short wave antennas mounted on a ship model are calculated. The results are obtained by different cores and various virtual topology. Then after analyzing the influence of topology schemes on parallel performance of Parallel FDTD on blade serve, the paper presents the best MPI virtual topology for Parallel FDTD based on blade serve.(6).An automatic modeling method is presented to transfer the triangular models, such as STL and RAW, into FDTD cubic models so that the core program is not corresponding with models. According to the conclusion of the best MPI virtual topology for Parallel FDTD based on blade server, the scattering character of some electrically large models is analyzed. At last, large broadside and narrow-wall slot arrays are analyzed on HP ProLiant BL460c.