Tai-Ming Chang¹, Chien-Chou Weng¹, Mei-Jiau Huang^1,2, Chun-KaiLiu², Chih-Kuang Yu²

CMES-Computer Modeling in Engineering & Sciences, Vol.50, No.1, pp. 47-66, 2009, DOI:10.3970/cmes.2009.050.047

Abstract We employ the non-equilibrium molecular dynamics (NEMD) simulation to calculate the in-plane thermal conductivity of silicon thin films of thickness 2.2nm and 11nm. To eliminate the finite-size effect, samples of various lengths are simulated and an extrapolation technique is applied. To perform the quantum correction which is necessary as the MD simulation temperature is lower than Debye temperature, the confined phonon spectra are obtained in advance via the EMD simulations. The investigation shows the thermal conductivities corrected based on the bulk and thin-film phonon densities of states are very close and they agree excellently with the theoretical predictions of a… More >

Chih-Fung Ho¹, Cheng Chang¹, Kuen-Hau Lin¹, Chao-An Lin^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.44, No.2, pp. 137-156, 2009, DOI:10.3970/cmes.2009.044.137

Abstract Consistent formulations of 2D and 3D pressure and velocity boundary conditions along both the stationary and non-stationary plane wall and corner for lattice Boltzmann simulations are proposed. The unknown distribution functions are made function of local known distribution functions and correctors, where the correctors at the boundary nodes are obtained directly from the definitions of density and momentum. This boundary condition can be easily implemented on the wall and corner boundary using the same formulation. Discrete macroscopic equation is also derived for steady fully developed channel flow to assess the effect of the boundary condition on the solutions, where the… More >

Shih-Kai Chien¹, Tzu-Hsiang Yen¹, Yue-Tzu Yang¹, Chao-Kuang Chen^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.3, pp. 163-174, 2008, DOI:10.3970/cmes.2008.029.163

Abstract Conventional proton exchange membrane fuel cells (PEMFCs) have a straight gas flow serpentine channel, and hence the reactant gases are transferred to the catalyst layers as a result of diffusion alone. Since the diffusion process is inherently slow, the electrical performance of such PEMFCs is inevitably limited. In an attempt to improve the PEMFC performance, this study replaces the straight channel with containing different type of obstacles and conducts a series of lattice Boltzmann method simulations to investigate the flow field phenomena induced in a viscous liquid as it flows along the serpentine channel at Reynolds numbers ranging from Re=5~25.… More >

E. Pan^1,2, Y. Zhang², P. W. Chung³, M. Denda⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 157-168, 2008, DOI:10.3970/cmes.2008.024.157

Abstract Quantum-dot (QD) semiconductor synthesis is one of the most actively investigated fields in strain energy band engineering. The induced strain fields influence ordering and alignment, and the subsequent surface formations determine the energy bandgap of the device. The effect of the strains on the surface formations is computationally expensive to simulate, thus analytical solutions to the QD-induced strain fields are very appealing and useful. In this paper we present an analytical method for calculating the QD-induced elastic field in anisotropic half-space semiconductor substrates. The QD is assumed to be of any polyhedral shape, and its surface is approximated efficiently by… More >

Cha’o-Kuang Chen¹, Shing-Cheng Chang¹, Szu-Yu Sun¹

CMES-Computer Modeling in Engineering & Sciences, Vol.22, No.3, pp. 203-216, 2007, DOI:10.3970/cmes.2007.022.203

Abstract In this study, the channel flow is discussed by the LBM simulations. In the cases of channel with obstacles inside, the square pillars play the role of causing interruption within the fluid field, and hence change the direction of fluid flow. The recirculation region is formed behind the obstacles and influences the fluid passed through not only in the velocity field but also in the temperature field. Therefore, heat transfer is enhanced in local region.
The field synergy principle is applied in the research to demonstrate that the increased interruption within the fluid increases the synergistic level between the… More >

K. Han ¹, Y. T. Feng ¹, D. R. J. Owen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.18, No.2, pp. 87-100, 2007, DOI:10.3970/cmes.2007.018.087

Abstract Numerical procedures are introduced for simulations of irregular particle transport in turbulent flows using the coupled lattice Boltzmann method (LBM) and the discrete element method (DEM). The fluid field is solved by the extended LBM with the incorporation of the Smagorinsky turbulence approach, while particle interaction is modeled by the DEM. The hydrodynamic interactions between fluid and particles are realised through an immersed boundary condition, which gives rise to a coupled solution strategy to model the fluid-particle system under consideration. Main computational aspects comprise the lattice Boltzmann formulation for the solution of fluid flows; the incorporation of the large eddy… More >

V.K. Tewary², D.T. Read²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.4, pp. 359-372, 2004, DOI:10.3970/cmes.2004.006.359

Abstract An integrated Green's function and molecular dynamics technique is developed for multiscale modeling of a nanostructure in a semi-infinite crystal lattice. The equilibrium configuration of the atoms inside and around the nanostructure is calculated by using molecular dynamics that accounts for nonlinear interatomic forces. The molecular dynamics is coupled with the lattice statics Green's function for a large crystallite containing a million or more atoms. This gives a fully atomistic description of a nanostructure in a large crystallite that includes the effect of nonlinear forces. The lattice statics Green's function is then related to the anisotropic continuum Green's function that… More >

Mohamed Ammar Abbassi¹, Bouchmel Mliki¹, Ridha Djebali^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.13, No.2, pp. 59-83, 2017, DOI:10.3970/fdmp.2017.013.059

Abstract This article reports a numerical study of nanoparticle Brownian motion and magnetic field effects by natural convection in a nanofluid-filled open cavity with non uniform boundary condition. Lattice Boltzmann Method (LBM) is used to simulate nanofluid flow and heat transfer. The effective thermal conductivity and viscosity of nanofluid are calculated by KKL (Koo-Kleinstreuer-Li) correlation. In this model effect of Brownian motion on the effective thermal conductivity and effective viscosity is considered and examined. Simulations have been carried out for the pertinent parameters in the following ranges: Rayleigh number (Ra=10³−10⁶), Hartmann number (Ha=0-60), nanoparticle volume concentration (Φ=0–0.04) and heat generation or… More >

Imen Mejri^1,2, Ahmed Mahmoudi¹

FDMP-Fluid Dynamics & Materials Processing, Vol.11, No.2, pp. 171-195, 2015, DOI:10.3970/fdmp.2015.011.171

Abstract This paper examines natural convection in an open cavity with a sinusoidal thermal boundary condition. The cavity is filled with a water-Al₂O₃ nanofluid and subjected to a magnetic field. The Lattice Boltzmann method (LBM) is applied to solve the coupled equations of flow and temperature. The study has been carried out considering parameters in the following ranges: Rayleigh number of the base fluid, Ra = 10³ to 10⁶, Hartmann number varied from Ha = 0 to 60, phase deviation γ = 0, π4, π2, 3 π4 and π and solid volume fraction of nanoparticles between π = 0 and 6%.… More >

Bouchmel Mliki, Mohamed Ammar Abbassi, Ahmed Omri

FDMP-Fluid Dynamics & Materials Processing, Vol.11, No.1, pp. 87-114, 2015, DOI:10.3970/fdmp.2015.011.087

Abstract MHD double-diffusive natural convective flow in a C-shaped enclosure filled with a Cu/Water nanofluid is investigated numerically using the Lattice Boltzmann Method (LBM). Much care is devoted to the validation of the numerical code. The effects exerted on the flow, concentration and temperature fields by different parameters such as the Rayleigh number (10³−10⁶), the nanoparticle volume concentration (0−0,1), the Lewis number (1-5), the Hartmann number (0−30) and different types of nanoparticles (Cu, Ag, Al₂O₃ and TiO₃ are assessed in detail. Results for stream function, Nusselt and Sherwood numbers are presented and discussed for various parametric conditions. Results indicate that the… More >