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  • Open Access


    Fast Searching Algorithm for Candidate Satellite-node Set in NLMG

    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 More >

  • Open Access


    A Galerkin-RBF Approach for the Streamfunction-Vorticity-Temperature Formulation of Natural Convection in 2D Enclosured Domains

    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 >

  • Open Access


    Numerical Solution of 2D Natural Convection in a Concentric Annulus with Solid-Liquid Phase Change

    R. Avila1, F.J. Solorio1

    CMES-Computer Modeling in Engineering & Sciences, Vol.44, No.2, pp. 177-202, 2009, DOI:10.3970/cmes.2009.044.177

    Abstract Heat transfer processes involving phase change either, solidification or melting, appear frequently in nature and in industrial applications. In this paper the convective patterns that arise from a 2D shear driven annular flow (without and with melting), are presented. The convective annular flow with radial gravity can be considered as a simplified model of the atmospheric flow in the terrestrial equatorial plane (bounded by the warm surface of the Earth and the cold tropopause). The governing equations have been numerically solved by the Spectral Element Method. The numerical results reported in this paper, for the… More >

  • Open Access


    Numerical Solution of Nonlinear Schrodinger Equations by Collocation Method Using Radial Basis Functions

    Sirajul Haq1,2, Siraj-Ul-Islam3, Marjan Uddin1,4

    CMES-Computer Modeling in Engineering & Sciences, Vol.44, No.2, pp. 115-136, 2009, DOI:10.3970/cmes.2009.044.115

    Abstract A mesh free method for the numerical solution of the nonlinear Schrodinger (NLS) and coupled nonlinear Schrodinger (CNLS) equation is implemented. The presented method uses a set of scattered nodes within the problem domain as well as on the boundaries of the domain along with approximating functions known as radial basis functions (RBFs). The set of scattered nodes do not form a mesh, means that no information of relationship between the nodes is needed. Error norms L2, L are used to estimate accuracy of the method. Stability analysis of the method is given to demonstrate its More >

  • Open Access


    Solution of Incompressible Turbulent Flow by a Mesh-Free Method

    R. Vertnik1, B. Šarler2

    CMES-Computer Modeling in Engineering & Sciences, Vol.44, No.1, pp. 65-96, 2009, DOI:10.3970/cmes.2009.044.065

    Abstract The application of the mesh-free Local Radial Basis Function Collocation Method (LRBFCM) in solution of incompressible turbulent flow is explored in this paper. The turbulent flow equations are described by the low - Re number k-emodel with Jones and Launder [Jones and Launder (1971)] closure coefficients. The involved velocity, pressure, turbulent kinetic energy and dissipation fields are represented on overlapping 5-noded sub-domains through collocation by using multiquadrics Radial Basis Functions (RBF). The involved first and second derivatives of the fields are calculated from the respective derivatives of the RBF's. The velocity, turbulent kinetic energy and… More >

  • Open Access


    A Simplified Analysis of the Tire-Tread Contact Problem using Displacement Potential Based Finite-Difference Technique

    S Reaz Ahmed1, S K Deb Nath1

    CMES-Computer Modeling in Engineering & Sciences, Vol.44, No.1, pp. 35-64, 2009, DOI:10.3970/cmes.2009.044.035

    Abstract The paper presents a simplified analysis of stresses and deformations at critical sections of a tire-tread. Displacement potential formulation is used in conjunction with the finite-difference method to model the present contact problem. The solution of the problem is obtained for two limiting cases of the contact boundary - one allows the lateral slippage and the other conforms to the no-slip condition along the lateral direction. The influential effects of tire material and tread aspect-ratio are discussed. The reliability and accuracy of the solution is also discussed in light of comparison made with the usual More >

  • Open Access


    A Highly Accurate Technique for Interpolations Using Very High-Order Polynomials, and Its Applications to Some Ill-Posed Linear Problems

    Chein-Shan Liu1, Satya N. Atluri2

    CMES-Computer Modeling in Engineering & Sciences, Vol.43, No.3, pp. 253-276, 2009, DOI:10.3970/cmes.2009.043.253

    Abstract Since the works of Newton and Lagrange, interpolation had been a mature technique in the numerical mathematics. Among the many interpolation methods, global or piecewise, the polynomial interpolation p(x) = a0 + a1x + ... + anxn expanded by the monomials is the simplest one, which is easy to handle mathematically. For higher accuracy, one always attempts to use a higher-order polynomial as an interpolant. But, Runge gave a counterexample, demonstrating that the polynomial interpolation problem may be ill-posed. Very high-order polynomial interpolation is very hard to realize by numerical computations. In this paper we propose a… More >

  • Open Access


    Hierarchical Adaptive Cross Approximation GMRES Technique for Solution of Acoustic Problems Using the Boundary Element Method

    A. Brancati1, M. H. Aliabadi1, I. Benedetti1,2

    CMES-Computer Modeling in Engineering & Sciences, Vol.43, No.2, pp. 149-172, 2009, DOI:10.3970/cmes.2009.043.149

    Abstract In this paper a new Rapid Acoustic Boundary Element Method (RABEM) is presented using a Hierarchical GMRES solver for 3D acoustic problems. The Adaptive Cross Approximation is used to generate both the system matrix and the right hand side vector. The ACA is also used to evaluate the potential and the particle velocity values at selected internal points. Two different GMRES solution strategies (without preconditioner and with a block diagonal preconditioner) are developed and tested for low and high frequency problems. Implementation of different boundary conditions (i.e. Dirichlet, Neumann and mixed Robin) is also described. More >

  • Open Access


    Matching Contours in Images through the use of Curvature, Distance to Centroid and Global Optimization with Order-Preserving Constraint

    Francisco P. M. Oliveira1, João Manuel R. S. Tavares1

    CMES-Computer Modeling in Engineering & Sciences, Vol.43, No.1, pp. 91-110, 2009, DOI:10.3970/cmes.2009.043.091

    Abstract This paper presents a new methodology to establish the best global match of objects' contours in images. The first step is the extraction of the sets of ordered points that define the objects' contours. Then, by using the curvature value and its distance to the corresponded centroid for each point, an affinity matrix is built. This matrix contains information of the cost for all possible matches between the two sets of ordered points. Then, to determine the desired one-to-one global matching, an assignment algorithm based on dynamic programming is used. This algorithm establishes the global More >

  • Open Access


    On the solution method for problems related to the micro-mechanics of a periodically curved fiber near a convex cylindrical surface

    Surkay D. Akbarov1,2,3, A. R. Mamedov3

    CMES-Computer Modeling in Engineering & Sciences, Vol.42, No.3, pp. 257-296, 2009, DOI:10.3970/cmes.2009.042.257

    Abstract Within the scope of the piecewise homogeneous body model through the use of the three-dimensional geometrically non-linear exact equations of the theory of elasticity, an approach for the investigation of problems with the micromechanics of a periodically curved fiber near the free convex cylindrical surface is proposed and employed. The main difficulties in finding the solution to these problems are caused by the impossibility of employing the summation theorem for cylindrical functions to satisfy the boundary conditions on the cylindrical surface. For this purpose the cosine and sine Fourier series presentation of the sought values More >

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