gping Shen¹, S. N. Atluri¹

CMC-Computers, Materials & Continua, Vol.1, No.1, pp. 59-90, 2004, DOI:10.3970/cmc.2004.001.059

Abstract This article provides a review of the computational nanomechanics, from the ab initio methods to classical molecular dynamics simulations, and multi- temporal and spatial scale simulations. The recent improvements and developments are briefly discussed. Their applications in nanomechanics and nanotubes are also summarized. More >

S.-C. Hsiao¹, M.S. Ingber²

CMC-Computers, Materials & Continua, Vol.1, No.1, pp. 51-58, 2004, DOI:10.3970/cmc.2004.001.051

Abstract The lateral migration of nonneutrally-buoyant spherical particles in Poiseuille flow is investigated numerically using the boundary element method. In particular, the steady, Navier-Stokes equations are solved using a classical domain integration method treating the nonlinear terms as pseudo-body forces. The numerical results for the lateral migration velocity are compared with experimental data. The numerical results indicate that the lateral migration velocity does not scale linearly with the Reynolds number. The methodology is extended to include non-Newtonian power-law fluids. The migration velocity is significantly affected for particles suspended in this class of fluids and can actually More >

X. Han^1,2,3, G. R. Liu^1,2, G. Y. Li ¹

CMC-Computers, Materials & Continua, Vol.1, No.1, pp. 39-50, 2004, DOI:10.3970/cmc.2004.001.039

Abstract An efficient hybrid numerical method is presented for investigating transient response of cross-ply laminated axisymmetric cylinders subjected to an impact load. In this hybrid numerical method, the laminated cylinder is divided into layered cylindrical elements in the thickness direction. The Hamilton principle is used to develop governing equations of the structure. The displacement response is determined by employing the Fourier transformations and the modal analysis. Numerical examples for analyzing transient waves have been provided in axisymmetric laminated cylindrical structures, both for thin cylindrical shells and thick cylinders.
A computational inverse technique is also presented for More >

Hokwon A. Cho¹, M. A. Golberg², A. S. Muleshkov¹, Xin Li¹

CMC-Computers, Materials & Continua, Vol.1, No.1, pp. 1-38, 2004, DOI:10.3970/cmc.2004.001.001

Abstract In this paper we present a mesh-free approach to numerically solving a class of second order time dependent partial differential equations which include equations of parabolic, hyperbolic and parabolic-hyperbolic types. For numerical purposes, a variety of transformations is used to convert these equations to standard reaction-diffusion and wave equation forms. To solve initial boundary value problems for these equations, the time dependence is removed by either the Laplace or the Laguerre transform or time differencing, which converts the problem into one of solving a sequence of boundary value problems for inhomogeneous modified Helmholtz equations. These… More >

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 >

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 >

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 >

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 >

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 >

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 >