Chun-Lang Yeh¹

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.3, pp. 175-210, 2010, DOI:10.3970/cmes.2010.067.175

Abstract Previous studies of nano-scale liquid threads have almost entirely been devoted to the investigation of a single liquid thread in a periodic fundamental cell. This paper is the first to study the vaporization process of two nano-scale liquid threads coexisting in a periodic fundamental cell by molecular dynamics (MD) simulation. Because of the interaction between the two liquid threads, the vaporization process is different from that of a single liquid thread in a periodic fundamental cell. This study discusses the influences of the liquid thread radius, fundamental cell length, and relative position of the two threads. Snapshots of molecules, the… More >

C. R. A. Silva¹, H. P. Azikri de Deus¹, G.E. Mantovani², A.T. Beck³

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.2, pp. 119-150, 2010, DOI:10.3970/cmes.2010.067.119

Abstract In this paper, the Askey-Wiener scheme and the Galerkin method are used to obtain approximate solutions to stochastic beam bending on Winkler foundation. The study addresses Euler-Bernoulli beams with uncertainty in the bending stiffness modulus and in the stiffness of the foundation. Uncertainties are represented by parameterized stochastic processes. The random behavior of beam response is modeled using the Askey-Wiener scheme. One contribution of the paper is a sketch of proof of existence and uniqueness of the solution to problems involving fourth order operators applied to random fields. From the approximate Galerkin solution, expected value and variance of beam displacement… More >

Che-Wun Hong^1,2, Chia-Yun Tsai¹

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.2, pp. 79-94, 2010, DOI:10.3970/cmes.2010.067.079

Abstract This paper describes the quantum mechanical simulation on the photonic properties of group-III nitride clusters, whose bulk types are common materials for light emitting diodes (LEDs). In order to emit different colors of light using the same semiconductor materials, it is possible to vary the band gap by controlling the quantum dot sizes or doping a third atom theoretically. Density functional theory (DFT) calculations are performed to analyze a set of binary (GaN)_n (3≤n≤32) and ternary In_xGa_1-xN (0≤x≤0.375) clusters to study their photonic characteristics. The ground state structures are optimized to calculate the binding energies using the time-independent DFT. Then… More >

J. Bonilla¹, L.J. Yebra¹, S. Dormido²

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.1, pp. 13-38, 2010, DOI:10.3970/cmes.2010.067.013

Abstract This paper presents and discusses a mean densities method applied to a steam-water two-phase flow mathematical model which uses a finite volume method and a staggered grid for discretizing a rigid volume in control volumes, where the thermodynamic properties are calculated. This method is based on the concepts of uniform pressure among all the control volumes and mean density in each control volume, allowing smooth thermodynamic properties, hence avoiding discontinuity at phase boundaries. This method wipes out the chattering problem due to the continuous and differentiable modelling of density and its partial derivatives, which leads to faster simulations and increases… More >

K. Kakuda¹, Y. Ushiyama¹, S. Obara¹, J. Toyotani¹, S. Matsuda², H.Tanaka², K. Katagiri²

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.3, pp. 215-226, 2010, DOI:10.3970/cmes.2010.066.215

Abstract The application of the MPS (Moving Particle Semi-implicit) scheme to incompressible viscous fluid flow problem in the liquid ring vacuum pump with rotating impeller is presented. The rotating impeller in the pump is attached to a center hub and located in off-set from the center of a cylindrical body. For such flow problem there are some interesting phenomena including the formation of the liquid ring by rotating impeller, the interface dynamics between gas and liquid, and so forth. The MPS scheme is widely utilized as a particle strategy for the free surface flow, the problem of moving boundary, and multi-physics/multi-scale… More >

B.I. Yun¹, W.T. Ang^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.65, No.3, pp. 217-244, 2010, DOI:10.3970/cmes.2010.065.217

Abstract A dual-reciprocity boundary element method is proposed for simulating numerically axisymmetric dual-phase-lag heat conduction in nonhomogeneous thermally isotropic media. The properties of the media, such as thermal conductivity and specific heat, are assumed to vary continuously in space. To check its validity and assess its accuracy, the proposed method is first applied to solve some specific test problems with known solutions. It is then used to simulate the axisymmetric dual-phase-lag heat conduction in a particular nonhomogeneous medium subject to a concentrated surface heating. The effects of the dual phase lags and the spatial variations of the thermal properties of the… More >

D. Kakogiannis¹, D. Van Hemelrijck¹, J. Wastiels¹, S. Palanivelu², W. Van Paepegem², J. Vantomme³, A. Kotzakolios⁴, V. Kostopoulos⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.65, No.1, pp. 75-94, 2010, DOI:10.3970/cmes.2010.065.075

Abstract In the present study the estimation of the blast wave by two types of finite element methods is investigated: Eulerian multi-material modeling and pure Lagrangian. The main goal is to compare and study their ability to predict the clearing effect during blast. Element shape and improvements on the codes are also considered. For the Lagrangian finite element models the load is applied by using an empirical method, deriving from databases, for the time-spatial distribution of the pressure profiles. In the ideal case of the above method the blast load is applied as an equivalent triangular pulse to represent the decay… More >

Hideki Fujii¹, Shinobu Yoshimura¹, Kazuya Seki¹

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.3, pp. 265-282, 2010, DOI:10.3970/cmes.2010.063.265

Abstract Traffic system is a typical complex system emerged through interactions among a large number of traffic actors such as car drivers, pedestrians and others. We model each actor as an intelligent agent that can judge and act by itself autonomously, and develop a traffic simulator named MATES, which is based on an intelligent multi-agent model. In this simulator, microscopic behaviors of the traffic actors cause macroscopic traffic phenomena through their interaction. In this research, we newly develop a coordinative behavior model among multiple cars, and implement it to MATES to enhance the reproducibility of traffic behaviors at merging sections. In… More >

Binxin Yang¹, Jie Ouyang¹, Tao Jiang¹, Chuntai Liu²

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.3, pp. 191-222, 2010, DOI:10.3970/cmes.2010.063.191

Abstract A gas-solid-liquid three-phase model is proposed for fiber reinforced composites mold filling process. The fluid flow is described in Eulerian coordinate while the dynamics of fibers is described in Langrangian coordinate. The interaction of fluid flow and fibers are enclosed in the model. The influence of fluid flow on fibers is described by the resultant forces imposed on fibers and the influence of fibers on fluid flow is described by the momentum exchange source term in the model. A finite volume method coupled with a level set method for viscoelastic-Newtonian fluid flow is used to solve the model. The direct… More >

Y. Inoue¹, R. Kobayashi¹, S. Ogata¹, T. Gotoh¹

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.2, pp. 137-162, 2010, DOI:10.3970/cmes.2010.063.137

Abstract Vibration of a single graphene and a pair of graphenes at micro meter scale induced by air flow is numerically simulated and examined by using a hybrid computational method starting from a microscopic level of description for the graphene. In order to bridge a huge gap in spatial and time scales in their motions, the carbon atoms of the graphene are represented by a small number of coarse grained particles, the fluid motion is described by the lattice Boltzmann equation and the momentum exchange at the boundary is treated by the time averaged immersed boundary method. It is found that… More >