New Development of Parallel Conformal FDTD Method in Computational Electromagnetics Engineering

We present a time domain hybrid method to realize the fast coupling analysis of transmission lines excited by space electromagnetic fields, in which parallel finite-difference time-domain (FDTD) method, interpolation scheme, and Agrawal model-based transmission line (TL) equations are organically integrated together. Specifically, the Agrawal model is employed to establish the TL equations to describe the coupling effects of space electromagnetic fields on transmission lines. Then, the excitation fields functioning as distribution sources in TL equations are calculated by the parallel FDTD method through using the message passing interface (MPI) library scheme and interpolation scheme. Finally, the TL equations are discretized by the central difference scheme of FDTD and assigned to multiple processors to obtain the transient responses on the terminal loads of these lines. The significant feature of the presented method is embodied in its parallel and synchronous calculations of the space electromagnetic fields and transient responses on the lines. Numerical simulations of ambient wave acting on multi-conductor transmission lines (MTLs), which are located on the PEC ground and in the shielded cavity respectively, are implemented to verify the accuracy and efficiency of the presented method.

A novel hybrid method combining 3D Parallel Finite- Difference Time-Domain (FDTD) method with Windowing technique through a new Controlling factor to study the Shielding Effectiveness (SE) of metallic cavities with apertures is firstly presented in this paper. The simulating time when the sampling electric field in cavity converges can be reduced greatly by the MPI-based Parallel FDTD method with the optimum virtual topology for the scattering problem. And then the sampling electric field in cavity is dealt with Windowing technique,which can further reduce the total time steps that Parallel FDTD method needs. The numerical results show that combination of Parallel FDTD with Windowing technique can enhance the simulating efficiency greatly. Finally,the SE of metallic cavities with different configurations is studied by the hybrid method and some useful conclusions to the practical electromagnetic shielding problems are obtained.

Ground penetrating radar (GPR), as a kind of fast, effective, and nondestructive tool, has been widely applied to nondestructive testing of road quality. The finite-difference time-domain method (FDTD) is the common numerical method studying the GPR wave propagation law in layered structure. However, the numerical accuracy and computational efficiency are not high because of the Courant-Friedrichs-Lewy (CFL) stability condition. In order to improve the accuracy and efficiency of FDTD simulation model, a parallel conformal FDTD algorithm based on graphics processor unit (GPU) acceleration technology and surface conformal technique was developed. The numerical simulation results showed that CUDA-implemented conformal FDTD method could greatly reduce computational time and the pseudo-waves generated by the ladder approximation. And the efficiency and accuracy of the proposed method are higher than the traditional FDTD method in simulating GPR wave propagation in two-dimensional (2D) complex underground structures.

In this paper, we present an analysis of electromagnetic environments in indoor offices using Finite Difference Time Domain (FDTD) method with MATLABMPI. The FDTD method is implemented by using MATLAB from The Mathworks, Inc. [3] and a parallel computation algorithm is realized by MATLABMPI [4].

This paper introduces a parallel FDTD (Finite Difference Time Domain) algorithm based on MPI (Message Passing Interface) parallel environment and NUMA (Non-Uniform Memory Access) architecture workstation. The FDTD computation is carried out independently in local meshes in each process. The data are exchanged by communication between adjacent subdomains to achieve the FDTD parallel method. The results show the consistency between serial and parallel algorithms, and the computing efficiency is improved effectively.

To explore the effects of CPU new technologies on parallel computation on a PC cluster, the parallel Finite Difference Time Domain (FDTD) is taken as a sample, and the power management (PowerNow, Turbo Core) is investigated by a set of numerical experiments on a PC cluster with 8-core AMD Fx-8120 CPUs. The results demonstrate that these technologies exhibit quite different impacts on the parallel FDTD. PowerNow can considerably drop the parallel efficiency in some specific operations such as inter-process communication. Turbo Core accelerates the computation in low CPU usage

Summary form only given. Modeling an electromagnetic (EM) structure with curved boundaries using a conformal finite-difference time-domain (CFDTD) method retains a second order accuracy while using a staircased FDTD one only gives a first order accuracy. In spite of the advantages to use the CFDTD method in EM simulations, the calculation of surface electric fields is performed by interpolation methods but usually gives unsatisfied results. In this work, a new algorithm being able to accurately determine surface electric fields near a curved surface has been developed and tested. The preliminary benchmark results show convergence that the surface electric fields can be calculated as accurately as higher than 99% using a 160 by 160 grid in 2D. Since the algorithm has been validated in 2D, a 3D counterpart is under development. Accurate determination of surface electric fields in CFDTD simulations is important for a lot of research studies such as surface breakdown, field emission, plasma wall interaction, etc. Detailed algorithm and benchmark results will be presented.

The use of Graphics Processing Unit (GPU) for computational work has revolutionized how complex electromagnetic problems are solved. Complex problems which required supercomputers in the past for analysis can now be tackled and solved using personal computers by channeling the computational work towards GPUs instead of the traditional computer Central Processing Unit (CPU). Finite-Difference Time-Domain (FDTD) analysis, which is a computationally expensive method of solving electromagnetic problems is highly parallel in nature and can be readily executed in a GPU. We have developed an algorithm for three dimensional FDTD analysis of optical devices with micro and nano-structures using Compute Unified Device Architecture (CUDA). The developed algorithm exploits the benefits of multiple cores of GPU chips and boosts the speed of simulation without sacrificing its accuracy. We achieved a 25-fold speed up of simulation using CUDA compared to MATLAB code in CPU.

Various methods are available at the disposal for computing the solution of electromagnetic problems expeditiously. Electromagnetic scattering problems can be classified into two broader categories named as surface and volume problems. These problems can be solved using differential and integral equations. Differential equations based techniques use Finite Element Method (FEM) and Finite Difference Time Domain (FDTD) methods and major integral formulation based technique is Method of Moment (MOM). Any set of linear equations for a given system can be solved using direct or iterative methods. Direct solvers confront many computational complexities and use large amount of memory while iterative solvers reduce computational complexities and use less amount of memory. In this research work some integral equations based solver schemes such ass Finite Element Method (FEM), Finite Difference Time Domain Method (FDTD) and Method of Moments (MOM) for surface and volume scatters are discussed and results are compared. The comparison is with respect to complexity and memory requirements for different solution schemes.

Finite-difference time-domain (FDTD) methods have long been the most popular solution for transient electromagnetic (TEM) modeling. Compared with FDTD methods, finiteelement time-domain (FETD) methods have the potential to reduce the number of unknowns and the number of time steps. However, with a requirement to solve an irregular and large sparse matrix equation at every time step, it is generally difficult for FETD methods to take advantage of massively parallel computers. In our work, we propose a parallel FETD solution for TEM diffusion phenomena. We design and implement a parallel iterative solver, which includes a preconditioner that is customized for the FETD method to achieve both fast convergence and good scalability. Using a seabed model, our experiments show that our parallel FETD solution provides the same accuracy as the FDTD methods. On the performance side, using 8 CPU cores, the iterative solver part runs 5 times faster than the serial verison, while the preconditioner part runs 3 times faster. In total, our parallel FETD method runs 3.5 times faster than the serial verison when simulating a seabed model with around 100,000 unknowns.

The Finite Difference Time-Domain (FDTD) method is a powerful tool for electromagnetic field analysis. In this work, we develop a variation of the algorithm to accurately calculate antenna, microwave circuit, and target scattering problems. To improve efficiency, a single-field (SF) FDTD method is proposed as a numerical solution to the time-domain Helmholtz equations. New formulas incorporating resistors and voltage sources are derived for the SF-FDTD algorithm, including hybrid implicit-explicit and weakly conditionally stable SF-FDTD methods. The correctness of these formulas is verified through numerical simulations of a newly designed dual-band wearable antenna with an artificial magnetic conductor (AMC) structure. A novel antenna fed by a coplanar waveguide with a compact size of 15.6 × 20 mm2 has been obtained after being optimized through an artificial intelligent method. A double-layer, dual-frequency AMC structure is designed to improve the isolation between the antenna and the human body. The simulation and experiment results with different bending degrees show that the antenna with the AMC structure can cover two frequency bands, 2.4 GHz-2.48 GHz and 5.725 GHz-5.875 GHz. The gain at 2.45 GHz and 5.8 GHz reaches 5.3 dBi and 8.9 dBi, respectively. The specific absorption rate has been reduced to the international standard range. In particular, this proposed SF-FDTD method can be extended to analyze other electromagnetic problems with fine details in one or two directions.

The Lorentz–Drude model incorporated Maxwell equations are simulated by using the three-dimensional finite difference time domain (FDTD) method and the method is parallelized on multiple graphics processing units (GPUs) for plasmonics applications. The compute unified device architecture (CUDA) is used for GPU parallelization. The Lorentz–Drude (LD) model is used to simulate the dispersive nature of materials in plasmonics domain and the auxiliary differential equation (ADE) approach is used to make it consistent with time domain Maxwell equations. Different aspects of multiple GPUs for the FDTD method are presented such as comparison of different numbers of GPUs, transfer time in between them, synchronous, and asynchronous passing. It is shown that by using multiple GPUs in parallel fashion, significant reduction in the simulation time can be achieved as compared to the single GPU.

Finite-difference time-domain (FDTD) method is one of the most popular approaches to solve electromagnetic problems. Furthermore, an important application of FDTD method is that FDTD method can analyze the transient response of the microwave integrate circuits by incorporating the active and passive devices into simulation [1]-[4]. However, when the active devices are incorporated into the FDTD cell grids, the updating equations of the grids would become nonlinear due to the nonlinear voltage-current relations of the active devices. To solve these nonlinear equations, an iterative method such as Netwon-Raphson algorithm, need to be employed. This work presents a novel efficient approach for the incorporation of diodes into FDTD method without applying the iterative method. The large-signal model of a diode is combined with Yee's time-stepping equations to update the electric field by solving a quadratic equation. An example is presented to demonstrate the accuracy of this algorithm.

In this paper, the well known Finite Difference Time Domain (FDTD) algorithm is utilized to design and analyze a number of planar printed microwave integrated circuits (MICs). Such designs and analyses are based on a developed FDTD computer solver. Prior to the designs, the solver has been validated through comparisons of its computed results with the ones which came from some analyzed structures previously published in other literature, and a good agreement has been observed. The results synthesized by the proposed designs lead to a strong belief that the FDTD is indeed a robust, versatile and powerful algorithm in solving various electromagnetic problems.

The paper presents a study and comparison of SAR induced in a prolate head model and a specific anthropomorphic mannequin (SAM) phantom using a mobile phone. To investigate systematic biases resulting from shape effect of the SAM and prolate head model, both the average SAR over a mass of 1g and 10g in the head models exposed to a dipole antenna are determined in different position cases. Using GEMS software which is based on the parallel Finite Difference Time Domain (FDTD) method, the differences between the results for prolate and SAM heads are discussed at 900MHz. Numerical results show the possibility to quickly assess electromagnetic radiation to human head using double layered prolate model.