Weiwei Gong, Yan Liu, Xiong Zhang, Honglei Ma

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.5, pp. 527-546, 2012, DOI:10.3970/cmes.2012.083.527

Abstract Owing to its low density and good energy absorption capability, aluminum foam is an excellent protective material for spacecraft against debris impact. However, because of its complicated microstructure, it is very difficult to generate a FEM mesh accounting for the real microstructure of the alluminum foam. On the contrary, it is very easy to model three-dimensional problems with very complicated geometry with meshfree/meshless methods. Furthermore, the material point method has obvious advantages in modeling problems involving extreme large deformation problems like hypervelocity impact problem. In this paper, a three-dimensional material point model accounting for the More >

Chein-Shan Liu

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.5, pp. 499-526, 2012, DOI:10.3970/cmes.2012.083.499

Abstract The iterative algorithms based on the concept of best vector are proposed to solve an ill-conditioned linear system: Bx-b=0, which might be a discretization of linear inverse problem. In terms of r:=Bx-b and a monotonically increasing positive function Q(t) of a time-like variable t, we define a future cone in the Minkowski space, wherein the discrete dynamics of the proposed algorithm is evolved. We propose two methods to approximate the best vector B-1r, and obtain three iterative algorithms for solving x, which we label them as the steepest-descent and optimal vectors iterative algorithm (SOVIA), the More >

D. Ngo-Cong, N. Mai-Duy, W. Karunasena, T. Tran-Cong

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.5, pp. 459-498, 2012, DOI:10.3970/cmes.2012.083.459

Abstract The partition of unity method is employed to incorporate the moving least square (MLS) and one dimensional-integrated radial basis function (1D-IRBFN) techniques in a new approach, namely local MLS-1D-IRBFN or LMLS-1D-IRBFN. This approach leads to sparse system matrices and offers a high level of accuracy as in the case of 1D-IRBFN method. A new numerical procedure based on the 1D-IRBFN method and LMLS-1D-IRBFN approach is presented for a solution of fluid-structure interaction (FSI) problems. A combination of Chorin's method and pseudo-time subiterative technique is presented for a transient solution of 2-D incompressible viscous Navier-Stokes equations More >

W. A. El-Askary, A. Abdel-Fattah

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.4, pp. 425-458, 2012, DOI:10.3970/cmes.2012.083.425

Abstract In the present paper, experimental and numerical studies of heat transfer and the frictional head loss of turbulent flow in a duct with a heated upper surface are performed. Four different arrangements are considered (case 1: without baffles, case 2: one perforated baffle on the upper wall and one solid baffle on the lower wall, case 3: one perforated baffle on the upper wall and one perforated baffle on the lower wall and case 4: two perforated baffles on the upper wall). A numerical code developed by the present authors is simultaneously presented including four… More >

Cao Guohua, Li Kai, Zhu Zhencai, Peng Weihong, Mao Xianbiao

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.4, pp. 403-424, 2012, DOI:10.3970/cmes.2012.083.403

Abstract In order to master the geometric and mechanical behavior of helical structure under complicated condition such as the hoisting rope in mine shaft and the transmitting cable in electric power, the thermal expansion characteristic of single helical structure is systematically investigated under temperature effect in different layer. Linearly explicit expressions of axial strain and increment of helical angle for the helical unit of the ith layer are developed. Based on theory of curve by Love and theory of wire rope by Costello, the linearly explicit expressions of tension, torsion and bending moment of the helical… More >

M. Chatterjee, A.K. Mahendra, A.Sanyal, G. Gouthaman

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.4, pp. 385-402, 2012, DOI:10.3970/cmes.2012.083.385

Abstract In this paper, we describe an Incompressible Navier-Stokes (INS) sol -ver using mesh less least square based discretisation on arbitrary distribution of points. The method uses modified Artificial Compressibility Method (ACM) with least square based discretisation. The Solver operates on an arbitrary distribution of points and uses a novel least squares based method that replaces the normal equations approach. This method generates the non-symmetric cross-product matrix by suitable selection of sub stencils such that the matrix is diagonally dominant and well conditioned. The INS solver has been validated with results available in literature for standard More >

Li Shan, Ning Cui, Ming Cheng, Kaixin Liu

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.4, pp. 353-384, 2012, DOI:10.3970/cmes.2012.083.353

Abstract In the present paper, a combined scheme of discrete element method (DEM) and meshless method for numerical simulation of impact problems is proposed. Based on the basic principle of continuum mechanics, an axisymmetric DEM framework is established for modeling the elastoplastic behavior of solid materials. Failure criteria are introduced to model the transformation from a continuum to a discontinuum. The friction force between contact elements is also considered after the failure appears. So our scheme can calculate not only the behavior of continuum and discontinuum, but also the transformation process from a continuum to a More >

D. Ngo-Cong^1,2, N. Mai-Duy¹, W. Karunasena², T. Tran-Cong^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.3, pp. 311-352, 2012, DOI:10.3970/cmes.2012.083.311

Abstract In this study, local moving least square - one dimensional integrated radial basis function network (LMLS-1D-IRBFN) method is presented and demonstrated with the solution of time-dependent problems such as Burgers' equation, unsteady flow past a square cylinder in a horizontal channel and unsteady flow past a circular cylinder. The present method makes use of the partition of unity concept to combine the moving least square (MLS) and one-dimensional integrated radial basis function network (1D-IRBFN) techniques in a new approach. This approach offers the same order of accuracy as its global counterpart, the 1D-IRBFN method, while More >

D. Ngo-Cong^1,2, N. Mai-Duy¹, W. Karunasena², T. Tran-Cong^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.3, pp. 275-310, 2012, DOI:10.3970/cmes.2012.083.275

Abstract In this paper, natural convection flows in concentric and eccentric annuli are studied using a new numerical method, namely local moving least square - one dimensional integrated radial basis function networks (LMLS-1D-IRBFN). The partition of unity method is used to incorporate the moving least square (MLS) and one dimensional-integrated radial basis function (1D-IRBFN) techniques in an approach that leads to sparse system matrices and offers a high level of accuracy as in the case of 1D-IRBFN method. The present method possesses a Kronecker-Delta function property which helps impose the essential boundary condition in an exact More >

Y.C. Cai¹, S.N. Atluri²

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.3, pp. 249-274, 2012, DOI:10.3970/cmes.2012.083.249

Abstract This paper presents a very simple finite element method for geometrically nonlinear large rotation analyses of plate/shell structures comprising of thin members. A fully nonlinear theory of deformation is employed in the updated Lagrangian reference frame of each plate element, to account for bending, stretching and torsion of each element. An assumed displacement approach, based on the Discrete Kirchhoff Theory (DKT) over each element, is employed to derive an explicit expression for the (18x18) symmetric tangent stiffness matrix of the plate element in the co-rotational reference frame. The finite rotation of the updated Lagrangian reference… More >