Yantao Zhang¹, Xiong Zhang^1,2, Yan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.69, No.2, pp. 143-166, 2010, DOI:10.3970/cmes.2010.069.143

Abstract Material point method(MPM) is a promising method in solving problems involving large deformations, especially explosion and penetration. In MPM, particles can move around the computing domain dynamically, which can result in load imbalance easily. In parallelizing MPM using OpenMP, data races will occur in the stage of grid node updating if we use loop-level parallelism for these loops. Huang et al. proposed a domain decomposition method to overcome data races [Huang, Zhang, Ma and Wang (2008)]. However, significant modifications of the original serial code are required. In this paper, we proposed a new alternated grid More >

Anant Diwakar¹, D. N.Srinath¹, Sanjay Mittal¹

CMES-Computer Modeling in Engineering & Sciences, Vol.69, No.1, pp. 61-90, 2010, DOI:10.3970/cmes.2010.069.061

Abstract Aerodynamic shape optimization of airfoils is carried out for two values of Reynolds numbers: 10³ and 10⁴, for an angle of attack of 5^o. The objective functions used are (a) maximization of lift (b) minimization of drag and (c) minimization of drag to lift ratio. The surface of the airfoil is parametrized by a 4^th order non-uniform rational B-Spline (NURBS) curve with 61 control points. Unlike the efforts in the past, the relatively large number of control points used in this study offer a rich design shape with the possibility of local bumps and valleys on the… More >

J. Sladek¹, V. Sladek¹, Ch. Zhang², M. Wünsche²

CMES-Computer Modeling in Engineering & Sciences, Vol.68, No.2, pp. 185-220, 2010, DOI:10.3970/cmes.2010.068.185

Abstract A meshless method based on the local Petrov-Galerkin approach is proposed to solve initial-boundary value crack problems of piezoelectric solids with nonlinear electrical boundary conditions on crack faces. Homogeneous and continuously varying material properties of the piezoelectric solid are considered. Stationary governing equations for electrical fields and the elastodynamic equations with an inertial term for mechanical 2-D fields are considered. Nodal points are spread on the analyzed domain, and each node is surrounded by a small circle for simplicity. The spatial variation of displacements and electric potential are approximated by the Moving Least-Squares (MLS) scheme. More >

Masato Saitoh¹

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.3, pp. 211-238, 2010, DOI:10.3970/cmes.2010.067.211

Abstract This paper describes the transformation of impedance functions in general structural systems with non-classical damping into a one-dimensional spring-dashpot system (1DSD). A transformation procedure based on complex modal analysis is proposed, where the impedance function is transformed into a 1DSD comprising units arranged in series. Each unit is a parallel system composed of a spring, a dashpot, and a unit having a spring and a dashpot arranged in series. Three application examples are presented to verify the applicability of the proposed procedure and the accuracy of the 1DSDs. The results indicate that the 1DSDs accurately… More >

Chun-Lang Yeh¹

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.3, pp. 175-210, 2010, DOI:10.3970/cmes.2010.067.175

Abstract Previous studies of nano-scale liquid threads have almost entirely been devoted to the investigation of a single liquid thread in a periodic fundamental cell. This paper is the first to study the vaporization process of two nano-scale liquid threads coexisting in a periodic fundamental cell by molecular dynamics (MD) simulation. Because of the interaction between the two liquid threads, the vaporization process is different from that of a single liquid thread in a periodic fundamental cell. This study discusses the influences of the liquid thread radius, fundamental cell length, and relative position of the two… More >

Xie Ming-Liang^1,2, Chan Tat-Leung², Yao Fu-Yuan³

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.1, pp. 39-54, 2010, DOI:10.3970/cmes.2010.067.039

Abstract A Fourier-Chebyshev Petrov-Galerkin spectral method is described for computation of temporal linear stability in a circular jet. The outer boundary of unbounded domains is truncated by large enough diameter. The mathematical formulation is presented in detail focusing on the analyticity of solenoidal vector field used for the approximation of the flow. The scheme provides spectral accuracy in the present cases studied and the numerical results are in agreement with former works. More >

J. Bonilla¹, L.J. Yebra¹, S. Dormido²

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.1, pp. 13-38, 2010, DOI:10.3970/cmes.2010.067.013

Abstract This paper presents and discusses a mean densities method applied to a steam-water two-phase flow mathematical model which uses a finite volume method and a staggered grid for discretizing a rigid volume in control volumes, where the thermodynamic properties are calculated. This method is based on the concepts of uniform pressure among all the control volumes and mean density in each control volume, allowing smooth thermodynamic properties, hence avoiding discontinuity at phase boundaries. This method wipes out the chattering problem due to the continuous and differentiable modelling of density and its partial derivatives, which leads More >

Delfim Soares Jr.¹

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.3, pp. 227-248, 2010, DOI:10.3970/cmes.2010.066.227

Abstract In this work, a meshless method based on the local Petrov-Galerkin approach is proposed for the solution of pore-dynamic problems considering elastic and elastoplastic materials. Formulations adopting the Heaviside step function as the test functions in the local weak form are considered. The moving least-square method is used for the approximation of physical quantities in the local integral equations. After spatial discretization is carried out, a nonlinear system of time-domain ordinary differential equations is obtained. This system is solved by Newmark/Newton-Raphson techniques. The present work is based on the u-p formulation and the incognita fields of More >

Xue-Qian Fang¹, Jin-Xi Liu¹, Ming-Zhang Chen¹, Li-Yong Fu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.2, pp. 101-116, 2010, DOI:10.3970/cmes.2010.066.101

Abstract In the authors' previous work (Zhang et al., 2010), the dynamic stress resulting from two cavities in exponential functional graded materials subjected to non-homogeneous shear waves has been studied. In this paper, the wave function expansion method is further developed to the case of two cylindrical inclusions embedded in functional graded materials, and the incident angle is also considered. The multiple scattering and refraction of non-homogeneous shear waves around the two inclusions are described accurately. The dynamic stress concentration factors around the two inclusions are presented analytically and numerically. The multiple effects of geometrical and More >

Alex Ferguson¹, Matthew R. Smith², J.-S. Wu³

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.1, pp. 79-100, 2010, DOI:10.3970/cmes.2010.063.079

Abstract A novel approach for the use of multiple continuous uniform distributions for reconstruction of the Maxwell-Boltzmann equilibrium probability distribution function is used for the solution of one and two dimensional Euler equations. The Uniform distribution Equilibrium Flux Method (UEFM) is a kinetic-theory based flux solver which calculates true directional, volume to volume fluxes based on integration (over velocity space and physical space) of a sum of uniform probability distribution functions working to approximate the equilibrium distribution function. The resulting flux expressions contain only the Heaviside unit step function and do not require the evaluation of More >