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  • Open Access

    ARTICLE

    Multiscale Simulations Using Generalized Interpolation Material Point (GIMP) Method And SAMRAI Parallel Processing

    J. Ma1, H. Lu1, B. Wang1, S. Roy1, R. Hornung2, A. Wissink2, R. Komanduri1,3

    CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.2, pp. 135-152, 2005, DOI:10.3970/cmes.2005.008.135

    Abstract In the simulation of a wide range of mechanics problems including impact/contact/penetration and fracture, the material point method (MPM), Sulsky, Zhou and Shreyer (1995), demonstrated its computational capabilities. To resolve alternating stress sign and instability problems associated with conventional MPM, Bardenhagen and Kober (2004) introduced recently the generalized interpolation material point (GIMP) method and implemented for one-dimensional simulations. In this paper we have extended GIMP to 2D and applied to simulate simple tension and indentation problems. For simulations spanning multiple length scales, based on the continuum mechanics approach, we present a parallel GIMP computational method using the Structured Adaptive Mesh… More >

  • Open Access

    ARTICLE

    Parallel Octree-Based Finite Element Method for Large-Scale Earthquake Ground Motion Simulation

    J. Bielak1, O. Ghattas2, E.-J. Kim3

    CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.2, pp. 99-112, 2005, DOI:10.3970/cmes.2005.010.099

    Abstract We present a parallel octree-based finite element method for large-scale earthquake ground motion simulation in realistic basins. The octree representation combines the low memory per node and good cache performance of finite difference methods with the spatial adaptivity to local seismic wavelengths characteristic of unstructured finite element methods. Several tests are provided to verify the numerical performance of the method against Green's function solutions for homogeneous and piecewise homogeneous media, both with and without anelastic attenuation. A comparison is also provided against a finite difference code and an unstructured tetrahedral finite element code for a simulation of the 1994 Northridge… More >

  • Open Access

    ARTICLE

    A Naturally Parallelizable Computational Method for Inhomogeneous Parabolic Problems

    M.Ganesh1, D. Sheen2

    CMES-Computer Modeling in Engineering & Sciences, Vol.2, No.2, pp. 183-194, 2001, DOI:10.3970/cmes.2001.002.183

    Abstract A parallel numerical algorithm is introduced and analyzed for solving inhomogeneous initial-boundary value parabolic problems. The scheme is based on the method recently introduced in Sheen, Sloan, and Thomée (2000) for homogeneous problems. We give a method based on a suitable choice of multiple parameters. Our scheme allows one to compute solutions in a wide range of time. Instead of using a standard time-marching method, which is not easily parallelizable, we take the Laplace transform in time of the parabolic problems. The resulting elliptic problems can be solved in parallel. Solutions are then computed by a discrete inverse Laplace transformation.… More >

  • Open Access

    ARTICLE

    Simulation of Dynamic Failure Evolution in Brittle Solids without Using Nonlocal Terms in the Strain-Stress Space

    Z. Chen1, W. Hu1, E.P. Chen2

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.4, pp. 57-62, 2000, DOI:10.3970/cmes.2000.001.509

    Abstract To simulate the dynamic failure evolution without using nonlocal terms in the strain-stress space, a damage diffusion equation is formulated with the use of a combined damage/plasticity model that was primarily applied to the case of rock fragmentation. A vectorized model solver is developed for large-scale simulation. Two-dimensional sample problems are considered to illustrate the features of the proposed solution procedure. It appears that the proposed approach is effective in simulating the evolution of localization, with parallel computing, in a single computational domain involving different lower-order governing differential equations. More >

  • Open Access

    ARTICLE

    Characteristics of a Hydromagnetic Non-Newtonian Squeeze Film Between Wide Parallel Rectangular Plates

    J.R. Lin1, T.L. Chou2, L.J. Liang2, M.C. Lin2, P.H. Lee2

    FDMP-Fluid Dynamics & Materials Processing, Vol.11, No.1, pp. 49-61, 2015, DOI:10.3970/fdmp.2015.011.049

    Abstract The characteristics of a hydromagnetic non-Newtonian squeeze film formed between parallel rectangular plates under the application on an external magnetic field are investigated. A specific hydromagnetic non-Newtonian Reynolds equation is derived via pplication of the hydromagnetic flow theory together with the micro-continuum theory. It is found that the coupled effects of electrically conducting fluids and micropolar fluids result in a higher load capacity and a longer approaching time with respect to the non-conducting Newtonian case. These improved characteristics become more pronounced as the magnetic Hartmann parameter, the coupling parameter, and the fluid-gap parameter are increased. More >

  • Open Access

    ARTICLE

    Numerical Simulation of Three Dimensional Low Prandtl Liquid Flow in a Parallelepiped Cavity Under an external Magnetic Field

    F. Mechighel1,2, M. El Ganaoui1, M. Kadja2, B. Pateyron3, S. Dost4

    FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.4, pp. 313-330, 2009, DOI:10.3970/fdmp.2009.005.313

    Abstract A numerical study has been carried out to investigate the three-dimen -sional buoyant flow in a parallelepiped box heated from below and partially from the two sidewalls (a configuration commonly used for solidification problems and crystal growth systems). Attention has been paid, in particular, to phenomena of symmetry breaking and transition to unsteady non-symmetric convection for a low Prandtl number fluid (Pr=0.01). The influence of an applied horizontal magnetic field on the stability properties of the flow has been also considered. Results obtained may be summarized as follows: In the absence of magnetic field and for relatively small values of… More >

  • Open Access

    ARTICLE

    Influence of Layer Height on Thermal Buoyancy Convection in A System with Two Superposed Fluids Confined in A Parallelepipedic Cavity

    Sunil Punjabi1, K. Muralidhar2, P. K. Panigrahi2

    FDMP-Fluid Dynamics & Materials Processing, Vol.2, No.2, pp. 95-106, 2006, DOI:10.3970/fdmp.2006.002.095

    Abstract Convection in a differentially heated two-layer system consisting of air and water was studied experimentally, using laser-interferometry. The cavity used for flow visualization was square in cross-section and rectangular in-plan having dimensions of 447 × 32 × 32 mm3. Experiments performed over different layer thicknesses of water filled in a square cross-section cavity, the rest being air, are reported in the present work. The following temperature differences for each layer height were imposed across the hot and the cold walls of the superposed fluid layers: (i) ΔT=10K and (ii)ΔT =18 K. The present study was aimed at understanding the following… More >

  • Open Access

    ARTICLE

    Numerical and Analytical Analysis of the Thermosolutal Convection in an Heterogeneous Porous Cavity

    K. Choukairy1, R. Bennacer2

    FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.2, pp. 155-172, 2012, DOI:10.3970/fdmp.2012.008.155

    Abstract This study carries the natural thermosolutal convection induced in heterogeneous porous media. The configuration considered is cartesian. The horizontal and vertical walls are submitted to different mass and heat transfer. The equations which govern this type of flow are solved numerically by using the finite volume method. The flow is considered two-dimensional and laminar. The model of Darcy and the approximation of the Boussinesq are taken into account. The parameters which control the problem are the thermal Darcy-Rayleigh number, Rt, the buoyancy ratio, N, the Lewis number, Le, the aspect ratio of the enclosure, A and the local permeability ratio,… More >

  • Open Access

    ARTICLE

    On the Nature and Structure of Possible Three-dimensional Steady Flows in Closed and Open Parallelepipedic and Cubical Containers under Different Heating Conditions and Driving Forces.

    Marcello Lappa1, 2

    FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.1, pp. 1-20, 2005, DOI:10.3970/fdmp.2005.001.001

    Abstract Possible natural transport mechanisms in cubical and shallow cavities with different heating conditions (from below or from the side) are investigated by means of numerical solution of the non-linear model equations and multiprocessor computations. Attention is focused on a variety of three-dimensional steady effects that can arise in such configurations in the case of low-Pr liquids (silicon melt) even for relatively small values of the temperature gradient due to localized boundary effects and/or true instabilities of the flow. Such aspects are still poorly known or completely ignored owing to the fact that most of the existing experiments focused on the… More >

  • Open Access

    ARTICLE

    Quantum Homomorphic Signature with Repeatable Verification

    Tao Shang1,*, Zhuang Pei2, Ranyiliu Chen3, Jianwei Liu1

    CMC-Computers, Materials & Continua, Vol.59, No.1, pp. 149-165, 2019, DOI:10.32604/cmc.2019.05360

    Abstract In January 2015, the first quantum homomorphic signature scheme was proposed creatively. However, only one verifier is allowed to verify a signature once in this scheme. In order to support repeatable verification for general scenario, we propose a new quantum homomorphic signature scheme with repeatable verification by introducing serial verification model and parallel verification model. Serial verification model solves the problem of signature verification by combining key distribution and Bell measurement. Parallel verification model solves the problem of signature duplication by logically treating one particle of an EPR pair as a quantum signature and physically preparing a new EPR pair.… More >

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