F. Dierich¹, P.A. Nikrityuk¹

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.3, pp. 251-266, 2010, DOI:10.3970/cmes.2010.064.251

Abstract This work presents a numerical investigation of the influence of the roughness of a cylindrical particle on the drag coefficient and the Nusselt number at low Reynolds numbers up to 40. The heated cylindrical particle is placed horizontally in a uniform flow. Immersed boundary method (IBM) with a continuous forcing on a fixed Cartesian grid is used. The governing equations are the Navier Stokes equation and the conservation of energy. A finite-volume based discretization and the SIMPLE algorithm with collocated-variables and Rie-Chow stabilization were used to solve the set of equations. Numerical simulations showed that More >

W. Wei¹, David C.C. Lam¹

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.2, pp. 213-226, 2010, DOI:10.3970/cmes.2010.064.213

Abstract Molecular rotation is the elastic deformation mechanism underpinning macroscopic deformation in macromolecular solid. In this investigation, molecular mechanic simulations are used to investigate the effect of size on the higher order material properties macromolecular solid. The rotational behavior of molecular coils embedded in beams was examined as a function of the beam size in tension, and in bending where the strain gradients in the bent direction are size-dependent. Analysis showed that the effective elastic modulus is size dependent when strain gradients are significant in bending, but not in tension. Analysis of the molecular rotation behavior More >

G. C. Bourantas¹, E. D. Skouras^2,3, V. C. Loukopoulos⁴, G. C. Nikiforidis¹

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.2, pp. 187-212, 2010, DOI:10.3970/cmes.2010.064.187

Abstract Meshfree point collocation method (MPCM) is developed, solving the velocity-vorticity formulation of Navier-Stokes equations, for two-dimensional, steady state incompressible viscous flow problems in the presence of heat transfer. Particular emphasis is placed on the application of the velocity-correction method, ensuring the continuity equation. The Gaussian Radial Basis Functions (GRBF) interpolation is employed to construct the shape functions in conjunction with the framework of the point collocation method. The cases of forced, natural and mixed convection in a 2D rectangular enclosure are examined. The accuracy and the stability of the proposed scheme are demonstrated through three More >

Surkay D. Akbarov^1,2, Nazmiye Yahnioglu³, Ayfer Tekin⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.2, pp. 147-186, 2010, DOI:10.3970/cmes.2010.064.147

Abstract A three-dimensional buckling delamination problem for the sandwich rectangular plate made from elastic and viscoelastic material is studied. It is supposed that the plate contains interface rectangular cracks (Case 1) and interface rectangular edge-cracks (Case 2) and edge-surfaces of these cracks have initial infinitesimal imperfections. The evolution of these initial imperfections with an external compressive loading acting along the cracks (for a case where the materials of layers of the plate are elastic) or with duration of time (for a case where the materials of layers of the plate are viscoelastic) is investigated within the… More >

S.H. Ju¹

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.1, pp. 91-109, 2010, DOI:10.3970/cmes.2010.064.091

Abstract This study develops an OpenMP scheme to parallel the preconditioned conjugate gradient methods (PCG) in shared memory computers. The proposed method is simple and systematic, so a minor change in traditional PCG methods may produce effective parallelism. At first, the global stiffness matrix is re-numbered in order to produce a parallel three-line form matrix, and a subroutine only needs to be called once in the finite element analysis. Several basic OpenMP commands are then added into the traditional incomplete Cholesky factorization (ILU) and symmetric successive over-relaxation (SSOR) codes to make the procedures of matrix multiplication, More >

Ismet Gölgeleyen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.1, pp. 71-90, 2010, DOI:10.3970/cmes.2010.064.071

Abstract In this paper, the solvability conditions for an inverse problem for an integro-differential transport equation are obtained and a numerical approximation method based on the finite difference method is developed. A comparison between the numerical solution and the exact solution of the problem is presented. Experimental results show that proposed method is robust to data noises. More >

E. Tonti, F. Zarantonello¹

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.1, pp. 37-70, 2010, DOI:10.3970/cmes.2010.064.037

Abstract This paper completes a preceeding paper on the algebraic formulation of elastostatics [Tonti, Zarantonello (2009)]. It shows how to obtain a numerical formulation for elastodynamics by avoiding any process of discretization of differential equations, i.e. PDE-free formulation. To this end, we must analyse in more detail the discretization of time by highlighting the need to introduce a dual subdivision of the time axis, as we did for a space cell complex. The mass matrix obtained with the direct algebraic formulation is diagonal. More >

A. Aimi¹, M. Diligenti¹, S. Panizzi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.58, No.2, pp. 185-220, 2010, DOI:10.3970/cmes.2010.058.185

Abstract In this paper we consider 2D wave propagation Neumann exterior problems reformulated in terms of a hypersingular boundary integral equation with retarded potential. Starting from a natural energy identity satisfied by the solution of the differential problem, the related integral equation is set in a suitable space-time weak form. Then, a theoretical analysis of the introduced formulation is proposed, pointing out the novelties with respect to existing literature results. At last, various numerical simulations will be presented and discussed, showing accuracy and stability of the space-time Galerkin boundary element method applied to the energetic weak More >

K. Kakuda¹, Y. Maeda¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.14, No.1, pp. 37-42, 2010, DOI:10.3970/icces.2010.014.037

Abstract The applications of a finite element scheme to one-dimensional linear advection-diffusion equation, the incompressible Navier-Stokes equations, and compressible Euler system of equations are presented. The mesh-based scheme is the Petrov-Galerkin weak formulation with exponential weighting functions. Some numerical results demonstrate the workability and the validity of the present approach. More >

Z Damian-Noriega¹, PA Lomeli-Mejia², SA Villanueva-Pruneda¹, R Pérez-Moreno¹, JPA Puerta-Huerta¹, E Montes-Estrada¹, GD Alvarez-Miranda¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.14, No.1, pp. 29-36, 2010, DOI:10.3970/icces.2010.014.029

Abstract The sizing of the component parts of a mechanical assembly must first assure its assembly and functionality and then the replacement (interchangeability) of used parts with new parts. For diametral fits (gaps and interferences) the ISO system of limits and fits is used, but for axial gaps the functional dimensioning method is applied to ensure maximum and minimum functional values. For each axial gap, the axial dimensions of the involved parts must be identified. Later, a minimal chain of dimensions is established, defined as the addition and subtraction of vectors parallel to the axis of More >