Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.21, No.1, pp. 53-66, 2007, DOI:10.3970/cmes.2007.021.053

Abstract A newly modified Trefftz method is developed to solve the exterior and interior Dirichlet problems for two-dimensional Laplace equation, which takes the characteristic length of problem domain into account. After introducing a circular artificial boundary which is uniquely determined by the physical problem domain, we can derive a Dirichlet to Dirichlet mapping equation, which is an exact boundary condition. By truncating the Fourier series expansion one can match the physical boundary condition as accurate as one desired. Then, we use the collocation method and the Galerkin method to derive linear equations system to determine the Fourier coefficients. Here, the factor… More >

Chein-Shan Liu ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.20, No.2, pp. 111-122, 2007, DOI:10.3970/cmes.2007.020.111

Abstract A highly accurate new solver is developed to deal with interior and exterior mixed-boundary value problems for two-dimensional Laplace equation, including the singular ones. To promote the present study, we introduce a circular artificial boundary which is uniquely determined by the physical problem domain, and derive a Dirichlet to Robin mapping on that artificial circle, which is an exact boundary condition described by the first kind Fredholm integral equation. As a consequence, we obtain a modified Trefftz method equipped with a characteristic length factor, ensuring that the new solver is stable because the condition number can be greatly reduced. Then,… More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.19, No.2, pp. 145-162, 2007, DOI:10.3970/cmes.2007.019.145

Abstract A new method is developed to solve the Dirichlet problems for the two-dimensional Laplace equation in the doubly-connected domains, namely the meshless regularized integral equations method (MRIEM), which consists of three portions: Fourier series expansion, the Fredholm integral equations, and linear equations to determine the unknown boundary conditions onartificial circles. The boundary integral equations on artificial circles are singular-free and the kernels are degenerate. When boundary-type methods are inefficient to treat the problems with complicated domains, the new method can be applicable for such problems. The new method by using the Fourier series and the Fourier coefficients can be adopted… More >

Chein-Shan Liu ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.19, No.1, pp. 99-110, 2007, DOI:10.3970/cmes.2007.019.099

Abstract A new meshless regularized integral equation method (MRIEM) is developed to solve the interior and exterior Dirichlet problems for the two-dimensional Laplace equation, which consists of three parts: Fourier series expansion, the second kind Fredholm integral equation and an analytically regularized solution of the unknown boundary condition on an artificial circle. We find that the new method is powerful even for the problem with complex boundary shape and with random noise disturbing the boundary data. More >

K. Yashiro¹, Y. Nakashima¹, Y. Tomita¹

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.2, pp. 73-80, 2006, DOI:10.3970/cmes.2006.011.073

Abstract A simple back force model is proposed for a dislocation cutting into γ' precipitate, taking the work formaking and recovering an anti-phase boundary (APB) into account. The first dislocation, or a leading partial of a superdislocation, is acted upon by a back force whose magnitude is equal to the APB energy. The second dislocation, or a trailing partial of a superdislocation, is attracted by the APB with a force of the same magnitude. The model is encoded in the 3D discrete dislocation dynamics (DDD) code and applied to the cutting behavior of dislocations at a γ/γ' interface covered by an… More >

S. Yoshimura ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.1, pp. 17-26, 2006, DOI:10.3970/cmes.2006.011.017

Abstract This paper describes a development of an advanced traffic simulator based on a multi-agent approach which is named MATES (Multi-Agent based Traffic and Environment Simulator). City traffic phenomena are essentially regarded as complex systems consisting of a number of human beings. Each element creating traffic phenomena such as car (driver), traffic signal, pedestrian and others is modeled as an intelligent agent that possesses its own logic of behavior and preference. The environment surrounding each agent consists of other cars, road network, traffic signals, pedestrian and others. Interaction among numerous agents simulates nonlinear behaviors of city traffic phenomena. First we describe… More >

B. F. Romanowicz¹, M. H. Zaman¹, S. F. Bart¹, V. L. Rabinovich¹, I. Tchertkov¹, S. Zhang¹, M. G. da Silva¹, M. Deshpande¹, K. Greiner¹, J. R. Gilbert¹, Shawn Cunningham²

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 45-64, 2000, DOI:10.3970/cmes.2000.001.045

Abstract Development of micro-electro-mechanical systems (MEMS) products is currently hampered by the need for design aids, which can assist in integration of all domains of the design. The cross-disciplinary character of microsystems requires a top-down approach to system design which, in turn, requires designers from many areas to work together in order to understand the effects of one sub-system on another. This paper describes current research on a methodology and tool-set which directly support such an integrated design process. More >

Hameed Muhamad¹, Simant Upreti ², Ali Lohi³, Huu Doan⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.12, No.3, pp. 111-123, 2016, DOI:10.3970/fdmp.2016.012.111

Abstract Heavy Oil is an up and coming energy resource that is aggressively being sought after as the world’s energy demand increases. As technology continues to improve, this once costly energy source is quickly becoming a more viable alternative. Vapor extraction (Vapex) process is an emerging technology for viscous oil recovery that has gained much attention in the oil industry. The vapor extraction of heavy oil system is presented to describe experimental setups and procedures used to perform different experiments of vape extraction process. The generated experimental data were used to calculate the live oil maximum interfacial solvent concentration as function… More >

Shaligram Tiwari¹, Koichi Nishino²

FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.1, pp. 109-136, 2010, DOI:10.3970/fdmp.2010.006.109

Abstract The present work reports about an experimental study investigating the influence of air convection and of ambient temperature around a half-floating zone on the transition behavior from steady to oscillatory flow, i.e. the influence on the critical Marangoni number (Macr). Increase of heat loss from the free surface of the half-floating zone or liquid bridge by increased convection and ambient cooling decreases Macr. Heat input to the free surface increases Macr. An add-on numerical simulation of the air convection around the zone clarifies the influence of air convection and the ambient temperature on the temperature, surface velocity and local Biot… More >

R. Abdeljabar¹, F. Onofri², M.J. Safi¹

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.4, pp. 245-254, 2008, DOI:10.3970/fdmp.2008.004.245

Abstract This paper focuses on the mechanisms of convective instability in a stable salty gradient layer (i.e. an interfacial salty layer). This layer is assumed to be initially confined between two homogeneous liquid layers: a lower layer composed of salty water of 5wt% concentration and an upper layer composed of distilled water. The mechanisms underlying the interfacial salty layer's instability are depicted experimentally using a PIV technique and via measurements of concentration and temperature. It is found that in addition to the effect of double-diffusion across the interfacial salty layer, different forms of Kelvin-Helmholtz instability occur at different locations:\newline i. At… More >