FDTD Parallel Computation Of Electrically Large Targets

Electrically large object is the target that the physical size is much larger than the incident wave length.While calculating the electromagnetic scattering of this kind of target,there will be a great deal of calculation and a large storage space is required.CPU occupancy rate is as high as 100% and insufficient virtual memory are often occurred under the serial computation.And these problems may cause the program to shut down or even a computer to crash.Faced with the limitation of the traditional single computer serial computing,we use the parallel computing to solve this problem.Parallel computing is the process of processing a task that has been divided into some processes,so as to achieve the goal of expanding the size of the object,improving the accuracy and reduce the calculation time.Nowadays,it is widely used in the large scale computation.As a tool,parallel algorithm,it can be well combined FDTD.With the ability to model complex structure,simulate a variety of materials environment,visualization of electromagnetic wave propagation process and other advantages,the FDTD method has shown great vitality in many fields,especially in the analysis of the electromagnetic scattering of the complex targets,in complex media and complex environment.This algorithm has been developed much rapidly in the last several decades.And its interpretation of the Maxwell equation provides a direct convenience for the realization of its parallel.1.Aiming at the electrically large objects which is complex,this paper uses 3D FDTD parallel algorithm to realize the electromagnetic scattering computation.It builds COW system,using the WINDOWS system,Visual Studio and MPICH2 software to establish the programming environment.Input the amount of processes,and the virtual topology with one-dimensional,two-dimensional or three-dimensional structure will be established by program automatically or artificially.2.This paper uses the Master-Slave model as the MPI programming model,the block message passing mechanism,creating new MPI derived data types to transfer the non-continuous data on the boundary of each process.3.Considering the problems,for instance,a great quantity of data,in the calculation of electrically large object,this paper optimizes the program to reduce the consumption of the program at run time.4.This paper calculates the Radar Cross Section(RCS)of typical targets.(1)It verifies the correctness of the parallel FDTD method in the calculations.(2)It studies the effect of grid segmentation accuracy on the calculation results.The results show that the requirement of parallel FDTD algorithm for grid segmentation accuracy is becoming more and more strict as the size of electrically large objects increases.(3)It studies the influence of different virtual topologies on time and performance of parallel FDTD algorithm.It is found that the topology has a great influence on the performance of parallel FDTD algorithm.(4)It analyses the usage of system resources of the different parallel scale.It is found that the the usage of resources is same when the system has same parallel scale.And the larger the size of scale,the higher the rate of resource use.5.Calculating complex objects and the objects with plasma.With less time step test,choose most ideal parallel scheme to calculate the RCS of the objects with harmonic incident.