G.R. Baker¹

CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.2, pp. 91-101, 2013, DOI:10.3970/cmes.2013.096.091

Abstract A vortex patch is a bounded region of uniform vorticity in twodimensional, incompressible, inviscid fluid flow. The streamfunction satisfies the Poisson equation with the vorticity acting as a source term. The standard formulation is to write the streamfunction as a convolution of the vorticity with the twodimensional free-space Greens function. A simple application of Greens theorem converts the area integral to a boundary integral. Numerical methods must then account for the singular nature of the boundary integral, and high accuracy is difficult when filamentation takes place, that is, when long, very thin filaments of vorticity erupt from the main boundary.… More >

T.W. Dong¹, H.S. Liu¹, S.L. Jiang², L.Gu¹, Q.W. Xiao¹, Z. Yu¹, X.F. Liu³

CMES-Computer Modeling in Engineering & Sciences, Vol.95, No.5, pp. 369-390, 2013, DOI:10.3970/cmes.2013.095.369

Abstract In this paper, we present a free surface flow model with a forced revolving moving boundary for partially filled screw extrusion. The incompressible smoothed particle hydrodynamics (ISPH) is used to simulate this complex flow. A set of organic glass experimental device for this partially filled fluid is manufactured. SPH results are satisfactorily compared with experiment results. The computed free surfaces are in good agreement with the free surfaces obtained from the experiment. Further analysis shows that with the increase of the speed, the average velocity of fluid increases, the effect of centrifugal force begin to show up, the maximum pressure… More >

H.T. Liu^1,2, Z. Chen², S. Jiang², Y. Gan³, M.B. Liu⁴, J.Z. Chang¹, Z.H. Tong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.95, No.4, pp. 303-315, 2013, DOI:10.3970/cmes.2013.095.303

Abstract Dissipative particle dynamics (DPD) and molecular dynamics (MD) are both Lagrangian particle-based methods with similar equations except that the DPD specification for the force definition on the particles is the result of coarsegraining, and these two methods usually get the similar results in some specific cases. However, there are still some unknown differences between them. Considering the water response to external force, a comparative study of DPD and MD is conducted in this paper, which provides a better understanding on their relation, and a potential way to effectively bridge nanoscale and mesoscale simulation procedures. It is shown that there is… More >

C. Delprete¹, F. Freschi², M. Repetto², C. Rosso¹

CMES-Computer Modeling in Engineering & Sciences, Vol.94, No.5, pp. 397-420, 2013, DOI:10.3970/cmes.2013.094.397

Abstract The growing necessity of accuracy in analyzing engineering problems requires more detailed and sophisticated models. Those models can include multiphysics interactions, that, sometimes, are highly nonlinear and the application of the superposition principle is then not possible. The cell method can be suitably used to study nonlinear multiphysics problems, because its theoretical framework for the physical laws is intrinsically multiphysics. In this way it is possible to take into account the mutual effects between different physics. Within the cell method framework, the coupling terms can be directly formulated in terms of the global variables used for the solution of the… More >

G. P. Nikishkov¹

CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.5, pp. 335-361, 2013, DOI:10.3970/cmes.2013.093.335

Abstract Accuracy of the quarter-point and transition elements is investigated on one- and two-dimensional problems with inverse square-root singularity. It is demonstrated that most coefficients of the stiffness matrix of the quarter-point element are unbounded. However, numerical integration produces finite values of these coefficients. Influence of several parameters on the error in determining the stress intensity factor is studied. Solution accuracy can be improved using special distribution of element sizes and increasing the element integration order in the radial direction. More >

K. Mramor¹, R. Vertnik^2,3, B. Šarler^1,3,4,5

CMES-Computer Modeling in Engineering & Sciences, Vol.92, No.4, pp. 327-352, 2013, DOI:10.3970/cmes.2013.092.327

Abstract The purpose of the present paper is to extend and explore the application of a novel meshless Local Radial Basis Function Collocation Method (LRBFCM) in solution of a steady, laminar, natural convection flow, influenced by magnetic field. The problem is defined by coupled mass, momentum, energy and induction equations that are solved in two dimensions by using local collocation with multiquadrics radial basis functions on an overlapping five nodded subdomains and explicit time-stepping. The fractional step method is used to couple the pressure and velocity fields. The considered problem is calculated in a square cavity with two insulated horizontal and… More >

Yasunori Yusa¹, Shinobu Yoshimura¹

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.6, pp. 445-461, 2013, DOI:10.3970/cmes.2013.091.445

Abstract For large-scale fracture mechanics simulation, a partitioned iterative coupling method is investigated. In this method, an analysis model is decomposed into two domains, which are analyzed separately. A crack is introduced in one small domain, whereas the other large domain is a simple elastic body. Problems concerning fracture mechanics can be treated only in the small domain. In order to satisfy both geometric compatibility and equilibrium on the domain boundary, the two domains are analyzed repeatedly using an iterative solution technique. A benchmark analysis was performed in order to validate the method and evaluate its computational performance. The computed stress… More >

G. Kosec^1,2, P. Zinterhof³

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.5, pp. 377-396, 2013, DOI:10.3970/cmes.2013.091.377

Abstract This paper deals with the implementation of the local meshless numerical method (LMM) on general purpose graphics processing units (GPU) in solving partial differential equations (PDE). The local meshless solution procedure is formulated in a way suitable for parallel execution and has been implemented on multiple GPUs. The implementation is tested on a solution of diffusion equation in a 2D domain. Different setups of the meshless approach regarding the selection of basis functions are tested on an interval up to 2.5 million of computational points. It is shown that monomials are a good selection of the basis when working with… More >

Guanghui Shi¹, Qingsheng Yang^1,2, Xiaoqiao He^3,4, Kim Meow Liew³

CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.5, pp. 339-358, 2013, DOI:10.3970/cmes.2013.090.339

Abstract In order to describe the thermomechanical deformation and shape memory effect of shape memory polymers (SMPs), a three-dimensional thermomechanical constitutive model that considers elastic, viscoelastic strain and thermal expansion is proposed for isotropic SMPs. A three-dimensional finite element procedure is developed by implementing the proposed constitutive model into the user material subroutine (UMAT) in ABAQUS program. Numerical examples are used to compare it with existing experimental data in a one dimensional case and to demonstrate the thermomechanical behavior of SMPs with 3D deformation. It is shown that the present constitutive theory and the finite element method can effectively simulate the… More >

Ashraf Balabel¹,

CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.4, pp. 283-301, 2012, DOI:10.3970/cmes.2012.089.283

Abstract This paper presents a novel numerical method for solving the twophase flow problems with moving interfaces in either laminar or turbulent flow regimes. The developed numerical method is based on the solution of the Reynolds- Averaged Navier Stokes equations in both phases separately with appropriate boundary conditions located at the interface separating the two fluids. The solution algorithm is performed on a regular and structured two-dimensional computational grid using the control volume approach. The complex shapes as well as the geometrical quantities of the interface are determined via the level set method. The numerical method is firstly validated against the… More >