B. Chandrasekhar¹

CMES-Computer Modeling in Engineering & Sciences, Vol.33, No.3, pp. 243-268, 2008, DOI:10.3970/cmes.2008.033.243

Abstract In this work, a novel numerical technique, based on method of moments solution, is presented to solve the Combined layer formulation (CLF) to insure unique solution to the exterior acoustic scattering problem at all frequencies. A new set of basis functions, namely, Node based basis functions are used to represent the source distribution on the surface of rigid body and the same functions are used as testing functions as well. Combined layer formulation (CLF) is defined by linearly combining the Single layer formulation (SLF) and Double layer formulation (DLF) with complex coupling parameter. The matrix equations for the SLF and… More >

Q. Ma¹, C. Levy², M. Perl³

CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.2, pp. 95-110, 2008, DOI:10.3970/cmes.2008.029.095

Abstract Networks of radial and longitudinally-coplanar, internal, surface cracks are typical in rifled, autofrettaged, gun barrels. In two previous papers, the separate effects of large arrays of either radial or longitudinally-coplanar semi-elliptical, internal, surface cracks in a thick-walled, cylindrical, pressure vessel under both ideal and realistic autofrettage were studied. When pressure is considered solely, radial crack density and longitudinal crack spacing were found to have opposing effects on the prevailing stress intensity factor, K_IP. Furthermore, the addition of the negative stress intensity factor (SIF), K_IA, resulting from the residual stress field due to autofrettage, whether ideal or realistic, tended to decrease… More >

S. S. Chen¹, Y. H. Liu^1,2, Z. Z. Cen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.1, pp. 39-56, 2008, DOI:10.3970/cmes.2008.028.039

Abstract In most engineering applications, solutions derived from the lower-bound theorem of plastic limit analysis are particularly valuable because they provide a safe estimate of the load that will cause plastic collapse. A solution procedure based on the meshless local Petrov-Galerkin (MLPG) method is proposed for lower-bound limit analysis. This is the first work for lower-bound limit analysis by this meshless local weak form method. In the construction of trial functions, the natural neighbour interpolation (NNI) is employed to simplify the treatment of the essential boundary conditions. The discretized limit analysis problem is solved numerically with the reduced-basis technique. The self-equilibrium… More >

B Radhika¹, S S P,a¹, C S Manohar^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.27, No.1&2, pp. 79-110, 2008, DOI:10.3970/cmes.2008.027.079

Abstract Reliability of nonlinear vibrating systems under stochastic excitations is investigated using a two-stage Monte Carlo simulation strategy. For systems with white noise excitation, the governing equations of motion are interpreted as a set of Ito stochastic differential equations. It is assumed that the probability distribution of the maximum in the steady state response belongs to the basin of attraction of one of the classical asymptotic extreme value distributions. The first stage of the solution strategy consists of selection of the form of the extreme value distribution based on hypothesis tests, and the next stage involves the estimation of parameters of… More >

M. Perl¹, C. Levy ², V. Rallabhandy ²

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.1, pp. 37-48, 2006, DOI:10.3970/cmes.2006.011.037

Abstract The Bauschinger Effect (BE) impact on K_IN– the combined, Mode I, 3-D Stress Intensity Factor (SIF) distributions for arrays of radial, internal, surface cracks emanating from the bore of a fully or partially autofrettaged thick-walled cylinder is investigated. A in-depth comparison between the combined SIFs for a “realistic” - Bauschinger Effect Dependent Autofrettage (BEDA) and those for an “ideal” - Bauschinger Effect Independent Autofrettage (BEIA) is performed. The 3- D finite element (FE) analysis is performed employing the submodeling technique and singular elements along the crack front. Both autofrettage residual stress fields, BEDA and BEIA, are simulated using an equivalent… More >

R. Martinez¹, N. M. Ghoniem²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.2, pp. 229-244, 2002, DOI:10.3970/cmes.2002.003.229

Abstract We focus here on the direct coupling of Dislocation Dynamics (DD) computer simulations with the Finite Element Method (FEM) to simulate plastic deformation of micro-scale structures, and investigate the influence of crystal surfaces on dislocation motion. A series of three-dimensional (3-d) DD simulations of BCC single crystals with a single shear loop in the (101)-[111] slip system are first presented. The purpose of these simulations is to explore the relationship between loop force distributions and the proximity of the loop to the crystal boundary. Traction boundary conditions on a single crystal model are satisfied through the superposition of the "image''… More >

Hamici Nadjib¹, Sahi Adel^1,*, Sadaoui Djamel¹, Djerrada Abderrahmane¹

FDMP-Fluid Dynamics & Materials Processing, Vol.14, No.3, pp. 155-175, 2018, DOI: 10.3970/fdmp.2018.01114

Abstract The study goes further to investigate a two-dimensional numerical model coupling free convection and surface radiation in an air-filled cavity containing a heated thin finned plate. The square enclosure is subjected to isothermal and insulated boundary conditions while the heating element location is varied from the horizontal position (HPFU, HPFD) to the vertical position (VPFL). The dimensionless governing equations under Boussinesq approximations are coupled with a radiative model through the boundaries conditions and solved by the Finite Volume Method. The effects of the pertinent parameters, namely, Rayleigh number (10³≤Ra≤10⁶), fin length (0.125≤L_a≤0.875), fin position (0.25≤H_a≤0.75) and wall emissivity (0≤ε≤1) are… More >

A. Khechiba¹, Y. Benakcha¹, A. Ghezal¹, P. Spetiri²

FDMP-Fluid Dynamics & Materials Processing, Vol.14, No.2, pp. 137-154, 2018, DOI: 10.3970/fdmp.2018.04054

Abstract This work investigates the dynamic behavior of a pulsatile flow electrically conducting through porous medium in a cylindrical conduit under the influence of a magnetic field. The imposed magnetic field is assumed to be uniform and constant. An exact solution of the equations governing magneto hydro-dynamics (MHD) flow in a conduit has been obtained in the form of Bessel functions. The analytical study has been used to establish an expression between the Hartmann number, Darcy number and the stress coefficient. The numerical method is based on an implicit finite difference time marching scheme using the Thomas algorithm and Gauss Seidel… More >

S. Hamimid^1,2, M. Guellal¹

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.3, pp. 377-393, 2014, DOI:10.3970/fdmp.2014.010.377

Abstract Combined laminar natural convection and surface radiation in a differentially heated square cavity has been investigated by a finite volume method through the concepts of staggered grid and SIMPLER approach. A power scheme has been also used in approximating advection–diffusion terms, determining the view factors by means of analytical expressions. The effect of emissivity on temperature and velocity profiles within the enclosure has been analyzed. In addition, results for local and average convective and radiative Nusselt numbers are presented and discussed for various conditions. More >

Mohamed Ammar Abbassi^1,2, Kamel Halouani¹, Xavier Chesneau³, Belkacem Zeghmati³

FDMP-Fluid Dynamics & Materials Processing, Vol.7, No.1, pp. 71-96, 2011, DOI:10.3970/fdmp.2011.007.071

Abstract Mixed convection inside a square cavity with inlet and outlet ports is numerically simulated considering thermal radiation effect. The non dimensional transfer equations, based on Boussinesq assumption and the radiative heat transfer equation are solved by the finite-volume-method and the TDMA algorithm. Results, presented for a gray fluid and a wide range of dimensionless numbers; Reynolds (Re=10-1000), Richardson (Ri=0-0.01), Boltzmann (Bo=0.1-100), radiation to conduction parameter (Rc=0.1-100), and optical thickness (τ = 0.1-10) show that the radiation significantly affects temperature distribution. Streamlines are also sensitive to radiative parameters (as optical thickness) but less than temperature. More >