CMES-Vol. 5, No. 5, 2004

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Parallel 3D Time Domain Electromagnetic Scattering Simulations on Unstructured Meshes
O. Hassan¹, K. Morgan, J. Jones, B. Larwood, N. P. Weatherill
CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 383-394, 2004, DOI:10.3970/cmes.2004.005.383
Abstract A numerical procedure for the simulation of 3D problems involving the scattering of electromagnetic waves is presented. As practical problems of interest in this area often involve domains of complex geometrical shape, an unstructured mesh based method is adopted. The solution algorithm employs an explicit finite element procedure for the solution of Maxwell's curl equations in the time domain using unstructured tetrahedral meshes. A PML absorbing layer is added at the artificial far field boundary that is created by the truncation of the physical domain prior to the numerical solution. The complete solution procedure is More >

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High-Order Accurate Methods for Time-domain Electromagnetics
J. S. Hesthaven¹, T. Warburton²
CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 395-408, 2004, DOI:10.3970/cmes.2004.005.395
Abstract We discuss the formulation, validation, and parallel performance of a high-order accurate method for the time-domain solution of the three-dimensional Maxwell's equations on general unstructured grids. Attention is paid to the development of a general discontinuous element/penalty approximation to Maxwell's equations and a locally divergence free form of this. We further discuss the motivation for using a nodal Lagrangian basis for the accurate and efficient representation of solutions and operators. The performance of the scheme is illustrated by solving benchmark problems as well as large scale scattering applications. More >

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Transform Domain Based Hybrid Element Formulations for Transient Electromagnetic Field Computations
P. Jose¹, R.Kanapady², K.K.Tamma³
CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 409-422, 2004, DOI:10.3970/cmes.2004.005.409
Abstract In this article, a novel hybrid finite element and Laplace transform formulation is presented for the computations of transient electromagnetic fields. The formulation is first based on application of Laplace transform technique for the pertinent differential equations, namely the Maxwell's equation in the non-integral form with subsequently, employing the Galerkin finite element formulations on the transformed equations to maintain the modeling versatility of complex geometries and numerical features for computational analysis. In addition, in conjunction with the above, proper scaling of the field quantities is applied to improve the condition of the effective global stiffness More >

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Hierarchical Vector Finite Elements with p-Type non-Overlapping Schwarz Method for Modeling Waveguide Discontinuities
Jin Fa Lee¹, Robert Lee², Fernando Teixeira³
CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 423-434, 2004, DOI:10.3970/cmes.2004.005.423
Abstract This paper presents the application of a p-type Multiplicative Schwarz Method (pMUS) for solving three dimensional waveguide discontinuity with arbitrary shapes. The major ingredients of current approach are: a hierarchical curl-conforming basis functions that incorporates an in-exact Helmholtz decomposition; and, treating each polynomial space (or basis functions group) as an abstract grid/domain in the Schwarz method. Various numerical examples are studied using the proposed approach. The performance has been compared to currently available commercial software and demonstrated superior performance in terms of accuracy as well as efficiency. More >

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The Characteristic Basis Function Method: A New Technique for Fast Solution of Radar Scattering Problems
Raj Mittra¹, V.V.S. Prakash¹
CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 435-442, 2004, DOI:10.3970/cmes.2004.005.435
Abstract In this paper, we introduce a novel approach for the efficient solution of electromagnetic scattering problems from objects that can be represented in terms of facets. The approach is based on the use of the Characteristic Basis Functions (CBFs), which are high-level basis functions of special types, and whose domains are not bound by the conventional Rao, Wilton and Glisson (RWG) discretization using triangular patches that are typically$\lambda$/10 to$\lambda$/20 in size. In contrast, the CBFs are defined over much larger-size domains, even tens of wavelengths in size, with no limit placed on the dimensions of… More >

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Scalable Electromagnetic Simulation Environment
Raju R. Namburu¹, Eric R. Mark, Jerry A. Clarke
CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 443-454, 2004, DOI:10.3970/cmes.2004.005.443
Abstract Computational electromagnetic (CEM) simulations of full-range military vehicles play a critical role in enhancing the survivability and target recognition of combat systems. Modeling of full-range military systems subjected to high frequencies may involve generating large-scale meshes, solving equations, visualization, and analysis of results in the range of billions of unknowns or grid points. Hence, the overall objective of this research is to develop and demonstrate a scalable CEM software environment to address accurate prediction of radar cross sections (RCS) for full- range armored vehicles with realistic material treatments and complex geometric configurations. A software environment… More >

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Application of MBPE Method to Frequency Domain Hybrid Techniques to Compute RCS of Electrically Large Objects
C. J. Reddy¹
CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 455-462, 2004, DOI:10.3970/cmes.2004.005.455
Abstract This paper presents an efficient algorithm to evaluate multi-spectral and multi-angular monostatic radar cross section (RCS) of large objects with very fine increments. The technique is based on the combination of Model Based Parameter Estimation (MBPE) method with hybrid frequency domain formulations. A general approach to formulation of MBPE is presented along with a similar approach called the Asymptotic Waveform Evaluation (AWE). Various numerical examples are presented for multi-spectral response calculations using method of moments (MoM) and the hybrid Finite Element-MoM technique in conjunction with MBPE. Example application of MBPE for hybrid MoM-Physical Optics approach More >

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Hybrid Finite Element and Volume Integral Methods for Scattering Using Parametric Geometry
John L. Volakis¹, Kubilay Sertel¹, Erik Jørgensen², Rick W. Kindt¹
CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 463-476, 2004, DOI:10.3970/cmes.2004.005.463
Abstract In this paper we address several topics relating to the development and implementation of volume integral and hybrid finite element methods for electromagnetic modeling. Comparisons of volume integral equation formulations with the finite element-boundary integral method are given in terms of accuracy and computing resources. We also discuss preconditioning and parallelization of the multilevel fast multipole method, and propose higher-order basis functions for curvilinear quadrilaterals and volumetric basis functions for curvilinear hexahedra. The latter have the desirable property of vanishing divergence within the element but non-zero curl. In addition, a new domain decomposition is introduced More >

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