S.M. Moussavinezhad¹, Farzad Shahabian¹, Seyed Mahmoud Hosseini^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.3, pp. 177-204, 2013, DOI:10.3970/cmes.2013.091.177

Abstract In this article, the propagation of elastic wave is studied in two dimensional functionally graded thick hollow cylinder with finite length subjected to mechanical shock loading, considering two dimensional variations for mechanical properties. The meshless local Petrov-Galerkin (MLPG) method is developed to solve the boundary value problem. The Newmark finite difference method is used to treat the time dependence of the variables for transient problems. The FG cylinder is considered to be under axisymmetric conditions. The mechanical properties of FG cylinder are assumed to vary across thickness and length of FG cylinder in terms of two dimensional volume fractions as… More >

António Tadeu^1,2, Julieta António¹, Patrícia Ferreira³

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.3, pp. 153-176, 2013, DOI:10.3970/cmes.2013.091.153

Abstract This paper presents an iterative coupling between a formulation based on the normal derivative of the integral equation (TBEM) and the method of fundamental solutions (MFS) for the transient analysis of acoustic wave propagation problems in the presence of multiple inclusions. The proposed formulation overcomes the individual limitations of each method, requires less computer memory and may use less CPU time than a full direct coupling formulation scheme. In the proposed formulation each inclusion is solved individually, successively, using the TBEM or the MFS and scatters a field that it is seen as an incident field at each of the… More >

Po-Jen Su¹, Cha’o-Kung Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.2, pp. 135-151, 2013, DOI:10.3970/cmes.2013.091.135

Abstract The residual correction method is used to predict the temperature distribution of non-Fourier heat transfer with time-dependent boundary condition. The approximate solution of temperature field is obtained by the residual correction method based on the maximum principle in combination with the finite difference method, making it easier and faster to obtain upper and lower approximations of exact solutions, and even can provide clear definitions of the maximum error bounds of the approximate solutions. The proposed method is found to be an effective numerical method with satisfactory accuracy. More >

Souli, M.¹, Aquelet, N.², Al-Bahkali, E.³, Moatamedi, M.⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.2, pp. 119-133, 2013, DOI:10.3970/cmes.2013.091.119

Abstract To simulate accurately a pressure wave propagation problem, a fine mesh is required in order to capture peak pressures accurately. This may require a very large size problem with several millions of elements. To reduce CPU time and prevent high mesh distortion, a two-dimensional problem for blast ignition and pressure propagation is performed first on a fixed Eulerian mesh. When the pressure wave gets closer to the structure, a three dimensional ALE simulation follows, where the fluid mesh and structure mesh at the fluid structure interface are coincident. The three dimensional problem is performed after mapping history variables from the… More >

J.H. Lv¹, Y. Miao^1,2, H.P. Zhu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.2, pp. 101-117, 2013, DOI:10.3970/cmes.2013.091.101

Abstract The accurate and efficient evaluation of nearly singular integrals is one of the major concerned problems in the implementation of the boundary element method (BEM). Among the various commonly used nonlinear transformation methods, the distance transformation technique seems to be a promising method to deal with various orders of nearly singular integrals both in potential and elasticity problems. In this paper, some drawbacks of the conventional distance transformation, such as the sensitivity to the position of projection point, are investigated by numerical tests. A general distance transformation technique is developed to circumvent these drawbacks, which is aimed to remove or… More >

Banghua Yao^1,2, Jianping Wei¹, Dengke Wang¹, Dan Ma^2,3, Zhanqing Chen²

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.2, pp. 81-100, 2013, DOI:10.3970/cmes.2013.091.081

Abstract Presently, there is an increasing number of water outburst accidents in China as mining activity continues to develop to deeper ground. In these accidents, water outburst caused by karst collapse columns often results in serious damage, involving both the loss of lives and significant economic loss. Therefore, it is of utmost importance to study the seepage property and water outburst mechanism of karst collapse columns. In this paper, based on the seepage theory and the groundwater dynamic theory of porous media, a fluid-solid coupling model for karst collapse columns was built and then imported into COMSOL Multiphysics to be solved,… More >

Xinhua Liu^1,2, Yongzhi Liu¹, Hao Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.1, pp. 65-80, 2013, DOI:10.3970/cmes.2013.091.065

Abstract In order to study the rheological characteristics of magnetorheological fluids, a simulation approach through integration of Monte Carlo method and GPU accelerated technology was proposed and the three-dimensional micro-structure of magnetic particles in different strength magnetic fields were simulated. The Monte Carlo method to magnetic particles of magnetorheological fluids and its key steps such as particle modeling, magnetic energy equations calculating and system state updating were elaborated. Moreover, GPU accelerated technology was applied to the simulation of magnetorheological fluids to reduce computational time and a flowchart for the proposed approach was designed. Finally, a physics experiment was carried out and… More >

Byung-Hyuk Lee¹, Se-min Jeong², Sung-Chul Hwang², Jong-Chun Park³, Moo-Hyun Kim⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.1, pp. 43-63, 2013, DOI:10.3970/cmes.2013.091.043

Abstract The violent free-surface motions interacting with floating vessels containing inner liquid tanks are investigated by using the newly developed Moving Particle Semi-implicit (MPS) method for 2-dimensional incompressible flow simulation. In the present numerical examples, many efficient and robust algorithms have been developed and applied to improve the overall quality and efficiency in solving various highly nonlinear free-surface problems and evaluating impact pressures compared to the original MPS method proposed by Koshizuka and Oka (1996). For illustration, the improved MPS method is applied to the simulation of nonlinear floating-body motions, violent sloshing motions and corresponding impact loads, and vessel motions with… More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.1, pp. 17-42, 2013, DOI:10.3970/cmes.2013.091.017

Abstract In the present paper, we propose a novel two-side equilibration method to properly reduce the condition number of a given non-singular matrix only through a few operations. Then, two different conditioners together with the conjugate gradient method (CGM) are developed, which can overcome the defect of CGM, being not vulnerable to noisy disturbance exerted on an ill-posed linear system. The twoside CGM (TSCGM) and the pre-conditioning CGM (PrCGM) are convergent fast and accurate in solving linear inverse problems and the linear Hilbert problem under a large random noise. More >

D. Bergmair^1,2, S. J. Metz¹, H. C. de Lange², A. A. van Steenhoven²

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.1, pp. 1-15, 2013, DOI:10.3970/cmes.2013.091.001

Abstract A method to predict the permeation of water vapor, present in a laminar flowing humid carrier gas, through a hollow fiber membrane is presented. The method uses simulation particles that move like molecules, according to the kinetic gas theory, but carry the physical properties of an ensemble of molecules which they statistically represent. With this approach an ideal operational window for membrane modules can be found and parameters tested for, can be varied over orders of magnitude. The results show that the right dimensioning is essential for the efficient use of the membrane area. More >