Roman Chapko¹, B. Tomas Johansson²

CMES-Computer Modeling in Engineering & Sciences, Vol.85, No.2, pp. 105-128, 2012, DOI:10.3970/cmes.2012.085.105

Abstract We consider a Cauchy problem for the Laplace equation in a 3-dimen -sional semi-infinite domain that contains a bounded inclusion. The canonical situation is the upper half-space in I\tmspace -.1667em R3 containing a bounded smooth domain. The function value of the solution is specified throughout the plane bounding the upper half-space, and the normal derivative is given only on a finite portion of this plane. The aim is to reconstruct the solution on the surface of the bounded inclusion. This is a generalisation of the situation in Chapko and Johansson (2008) to three-dimensions and with… More >

Li Shan, Ning Cui, Ming Cheng, Kaixin Liu

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.4, pp. 353-384, 2012, DOI:10.3970/cmes.2012.083.353

Abstract In the present paper, a combined scheme of discrete element method (DEM) and meshless method for numerical simulation of impact problems is proposed. Based on the basic principle of continuum mechanics, an axisymmetric DEM framework is established for modeling the elastoplastic behavior of solid materials. Failure criteria are introduced to model the transformation from a continuum to a discontinuum. The friction force between contact elements is also considered after the failure appears. So our scheme can calculate not only the behavior of continuum and discontinuum, but also the transformation process from a continuum to a More >

Y.C. Cai¹, S.N. Atluri²

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.3, pp. 249-274, 2012, DOI:10.3970/cmes.2012.083.249

Abstract This paper presents a very simple finite element method for geometrically nonlinear large rotation analyses of plate/shell structures comprising of thin members. A fully nonlinear theory of deformation is employed in the updated Lagrangian reference frame of each plate element, to account for bending, stretching and torsion of each element. An assumed displacement approach, based on the Discrete Kirchhoff Theory (DKT) over each element, is employed to derive an explicit expression for the (18x18) symmetric tangent stiffness matrix of the plate element in the co-rotational reference frame. The finite rotation of the updated Lagrangian reference… More >

F. Moufekkir¹, M.A. Moussaoui¹, A. Mezrhab^1,2, H. Naji^3,4, M. Bouzidi⁵

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.2, pp. 129-154, 2012, DOI:10.3970/fdmp.2012.008.129

Abstract The problem related to coupled double diffusive convection in a square enclosure filled with a gray gas in the presence of volumetric radiation is examined numerically. The horizontal walls are assumed to be insulated and impermeable. Different temperatures and species concentrations are imposed at vertical walls. In particular, we propose a 2-D numerical approach based on a hybrid scheme combining a multiple-relaxation-time lattice Boltzmann model (MRT-LBM) and a standard finite difference method (FDM). The radiative term in the energy equation is treated using the discrete ordinates method (DOM) with a S8 quadrature. The influence of… More >

Muhammad M. Rahman^*, Phaninder Injeti

Frontiers in Heat and Mass Transfer, Vol.2, No.1, pp. 1-9, 2011, DOI:10.5098/hmt.v2.1.3003

Abstract This paper presents the effects of protrusions on heat transfer in a microtube and in a two-dimensional microchannel of finite wall thickness. The effects of protrusion shape, size, and number were investigated. Calculations were done for incompressible flow of a Newtonian fluid with developing momentum and thermal boundary layers under uniform and discrete heating conditions. It was found that the local Nusselt number near a protrusion changes significantly with the variations of Reynolds number, height, width, and distance between protrusions, and the distribution of discrete heat sources. The results presented in the paper demonstrate that More >

V.K. Tewary

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.4, pp. 113-114, 2011, DOI:10.3970/icces.2011.019.113

Abstract Interfacial region between two nanomaterials can be treated as a separate material since its atomistic structure and characteristics are different than the two materials on its either side. The mechanical as well as electronic properties of composite materials are sensitive to the interfaces. For industrial application of the nanomaterial systems, it is vital to model and measure the discrete atomistic locations in the interface during operating conditions. As the dimensions of nanomaterial systems shrink, the role of interfaces become increasingly important. Because of its nanothickness, the conventional characterization and design parameters like elastic constants, stress… More >

Renpeng Chen, Linggang kong, Lvjun Tang, Yunmin Chen

The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.4, pp. 99-100, 2011, DOI:10.3970/icces.2011.020.099

Abstract Face stability is critical in the underground tunneling. In this report, large-scale model tests on the face stability of shallow tunnels for various cover depths (C/D = 0.5, 1, and 2) in dry sandy ground were firstly introduced. Then, a series of three-dimensional DEM models were built to simulated the process of tunnel face failure. The results of the model tests and DEM simulations reveal that a chimney like failure zone appears during the tunnel face failure. It was founded that with the increase of the horizontal displacement of the tunnel face, the support pressure More >

Li Shan, Ming Cheng, Kaixin Liu

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.3, pp. 87-88, 2011, DOI:10.3970/icces.2011.019.087

Abstract In the present paper, a combined scheme of discrete element method (DEM) and meshless method for numerical simulation of impact problems is proposed. Based on the basic principle of continuum mechanics, an axisymmetric DEM framework is estabilished for modeling the elastoplastic behavior of solid materials. A failure criterion is introduced to model the transformation from a continuum to a discontinuum. The friction force between contact elements is also considered after the failure appears. So our scheme can calculate not only the behavior of continuum and discontinuum, but also the transformation process from continuum to discontinuum. More >

Jorge Daniel Riera¹, Letícia Fleck Fadel Miguel², Ignacio Iturrioz³

CMES-Computer Modeling in Engineering & Sciences, Vol.82, No.2, pp. 113-136, 2011, DOI:10.32604/cmes.2011.082.113

Abstract In the truss-like Discrete Element Method (DEM), masses are considered lumped at nodal points and interconnected by means of uni-dimensional elements with arbitrary constitutive relations. In previous studies of the tensile fracture behavior of concrete cubic samples, it was verified that numerical predictions of fracture of non-homogeneous materials using DEM models are feasible and yield results that are consistent with the experimental evidence so far available. Applications that demand the use of large elements, in which extensive cracking within the elements of the model may be expected, require the consideration of the increase with size… More >

Y.C. Cai^1,2,3, L.G. Tian¹, S.N. Atluri³

CMES-Computer Modeling in Engineering & Sciences, Vol.77, No.3&4, pp. 221-238, 2011, DOI:10.3970/cmes.2011.077.221

Abstract A new three node triangular plate element, labeled here as DST-S6 (Discrete Shear Triangular element with 6 extra Shear degrees of freedom), is proposed for the analyses of plate/shell structures comprising of thin or thick members. The formulation is based on the DKT (Discrete Kirchhoff Technique) and an appropriate use of the independent shear DOF(Degrees Of Freedom). The shear locking is completely eliminated in the DST-S6, without any numerical expediencies such as the reduce integration, the use of assumed strains/stresses, or the need for the stabilization of the attendant zero energy modes. It is shown… More >