Mustafa Yildiz¹

CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.2, pp. 141-154, 2009, DOI:10.3970/cmes.2009.045.141

Abstract The solvability conditions of an inverse problem for the non-stationary kinetic equation is formulated and a new numerical method is developed to obtain the approximate solution of the problem. A comparison between the approximate solution and the exact solution of the problem is presented. More >

M. Trikha¹, S. Gopalakrishnan², D. Roy Mahapatra^2,1, R. Pandiyan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.2, pp. 97-140, 2009, DOI:10.3970/cmes.2009.045.097

Abstract A mechanics based linear analysis of the problem of dynamic instabilities in slender space launch vehicles is undertaken. The flexible body dynamics of the moving vehicle is studied in an inertial frame of reference, including velocity induced curvature effects, which have not been considered so far in the published literature. Coupling among the rigid-body modes, the longitudinal vibrational modes and the transverse vibrational modes due to asymmetric lifting-body cross-section are considered. The model also incorporates the effects of aerodynamic forces and the propulsive thrust of the vehicle. The effects of the coupling between the combustion process (mass variation, developed thrust… More >

Alexandre de Castro^1,2, Carlos Frederico Fronza², Domingos Alves^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.1, pp. 83-96, 2009, DOI:10.3970/cmes.2009.045.083

Abstract Immunological systems have been an abundant inspiration to contemporary computer scientists. Problem solving strategies, stemming from known immune system phenomena, have been successfully applied to chall enging problems of modern computing. Simulation systems and mathematical modeling are also beginning use to answer more complex immunological questions as immune memory process and duration of vaccines, where the regulation mechanisms are not still known sufficiently (Lundegaard, Lund, Kesmir, Brunak, Nielsen, 2007). In this article we studiedin machinaa approach to simulate the process of antigenic mutation and its implications for the process of memory. Our results have suggested that the durability of the… More >

Dongdong Wang^1,2, Yue Sun², Ling Li²

CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.1, pp. 57-82, 2009, DOI:10.3970/cmes.2009.045.057

Abstract A discontinuous Galerkin meshfree formulation is proposed to solve the potential and elasticity problems of composite material where the material interface has to be appropriately modeled. In the present approach the problem domain is partitioned into patches or sub-domains and each patch holds the same material properties. The discretized meshfree particles within a patch are classified as one particle group. Various patches occupied by different particle groups are then linked using the discontinuous Galerkin formulation where an averaged interface flux or traction is constructed based on the fluxes or tractions computed from the adjacent patches. The gradient jump condition across… More >

Yufeng Nie¹, Ying Liu², Yuantong Gu³, Xiangkuo Fan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.1, pp. 31-56, 2009, DOI:10.3970/cmes.2009.045.031

Abstract The Node-based Local Mesh Generation (NLMG) algorithm, which is free of mesh inconsistency, is one of core algorithms in the Node-based Local Finite Element Method (NLFEM) to achieve the seamless link between mesh generation and stiffness matrix calculation, and the seamless link helps to improve the parallel efficiency of FEM. Furthermore, the key to ensure the efficiency and reliability of NLMG is to determine the candidate satellite-node set of a central node quickly and accurately. This paper develops a Fast Local Search Method based on Uniform Bucket (FLSMUB) and a Fast Local Search Method based on Multilayer Bucket (FLSMMB), and… More >

Xiaolin Li¹, Jialin Zhu²

CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.1, pp. 1-30, 2009, DOI:10.3970/cmes.2009.045.001

Abstract In this paper, a Galerkin boundary node method (GBNM) is developed for boundary-only analysis of 2D problems in linear elasticity. The GBNM combines the variational form of a boundary integral formulation for the elastic equations with the moving least-squares approximations for generating the trial and test functions. Unlike the boundary node method, the main idea here is to use the Galerkin scheme for numerical analysis, thus boundary conditions in the GBNM can be satisfied easily and directly in the weak formulation of the boundary integral equation. Another advantage with the Galerkin scheme is that the GBNM can keep the symmetry… More >

Chein-Shan Liu¹, Weichung Yeih², Satya N. Atluri³

CMES-Computer Modeling in Engineering & Sciences, Vol.44, No.3, pp. 281-312, 2009, DOI:10.3970/cmes.2009.044.281

Abstract Here we develop a general purpose pre/post conditionerT, to solve an ill-posed system of linear equations,Ax=b. The conditionerTis obtained in the course of the solution of the Laplace equation, through a boundary-collocation Trefftz method, leading to:Ty=x, whereyis the vector of coefficients in the Trefftz expansion, andxis the boundary data at the discrete points on a unit circle. We show that the quality of the conditionerTis greatly enhanced by using multiple characteristic lengths (Multiple Length Scales) in the Trefftz expansion. We further show thatTcan be multiplicatively decomposed into a dilationTDand a rotationTR. For an odd-orderedA, we develop four conditioners based on… More >

Cheng-Hung Huang¹, Yun-Lung Chung¹

CMES-Computer Modeling in Engineering & Sciences, Vol.44, No.3, pp. 249-280, 2009, DOI:10.3970/cmes.2009.044.249

Abstract The optimum shapes for the longitudinal and spine fully wet fins are estimated in the present inverse design problem by using the conjugate gradient method (CGM) based on the desired fin efficiency and fin volume. One of the advantages in using CGM in the inverse design problem lies in that it can handle problems having a large number of unknown parameters easily and converges very fast. Results obtained by using the CGM to solve the inverse design problems are justified based on the numerical experiments. Results show that when the Biot number and relative humidity are varied, the optimum fin… More >

D. Ho-Minh¹, N. Mai-Duy¹, T. Tran-Cong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.44, No.3, pp. 219-248, 2009, DOI:10.3970/cmes.2009.044.219

Abstract This paper reports a new discretisation technique for the streamfunc -tion-vorticity-temperature (ψ−ω−T) formulation governing natural convection defined in 2D enclosured domains. The proposed technique combines strengths of three schemes, i.e. smooth discretisations (Galerkin formulation), powerful high-order approximations (one-dimensional integrated radial-basis-function networks) and pressure-free low-order system (ψ−ω−T formulation). In addition, a new effective way of deriving computational boundary conditions for the vorticity is proposed. Two benchmark test problems, namely free convection in a square slot and a concentric annulus, are considered, where a convergent solution for the former is achieved up to the Rayleigh number of 10⁸. More >

Chia-Yi Cheng, Cha’o-Kuang Chen¹, Yue-Tzu Yang

CMES-Computer Modeling in Engineering & Sciences, Vol.44, No.3, pp. 203-218, 2009, DOI:10.3970/cmes.2009.044.203

Abstract This paper seeks to utilize the residual correction method in coordination with the evolutionary monotonic iteration technique to obtain upper and lower approximate solutions of non-linear heat transfer problem of the annular hyperbolic profile fins whose thermal conductivity vary with temperature. First, the monotonicity of a non-linear differential equation is reinforced by using the monotone iterative technique. Then, the cubic spline method is applied to discretize and convert the differential equation into the mathematical programming problems. Finally, based on the residual correction concept, the complicated constraint inequality equations can be transferred into the simple iterative equations. As verified by this… More >