Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.27, No.3, pp. 137-150, 2008, DOI:10.3970/cmes.2008.027.137

Abstract For the inverse vibration problem, a Lie-group shooting method is proposed to simultaneously estimate the time-dependent damping and stiffness functions by using two sets of displacement as inputs. First, we transform these two ODEs into two parabolic type PDEs. Second, we formulate the inverse vibration problem as a multi-dimensional two-point boundary value problem with unknown coefficients, allowing us to develop the Lie-group shooting method. For the semi-discretizations of PDEs we thus obtain two coupled sets of linear algebraic equations, from which the estimation of damping and stiffness coefficients can be written out explicitly. The present approach is very interesting, which… More >

D. Soares Jr.¹, W.J. Mansur^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.2, pp. 153-164, 2005, DOI:10.3970/cmes.2005.008.153

Abstract A coupling procedure is described to perform time-domain numerical analyses of dynamic fluid-structure interaction. The fluid sub-domains, where acoustic waves propagate, are modeled by the Boundary Element Method (BEM), which is quite suitable to deal with linear homogeneous unbounded domain problems. The Finite Element Method (FEM), on the other hand, models the structure sub-domains, adopting a time marching scheme based on implicit Green's functions. The BEM/FEM coupling algorithm here developed is very efficient, eliminating the drawbacks of standard and iterative coupling procedures. Stability and accuracy features are improved by the adoption of different time steps in each sub-domain of the… More >

M. Kröger¹, M. Müller², J. Nievergelt²

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.5, pp. 559-570, 2003, DOI:10.3970/cmes.2003.004.559

Abstract We present a novel method for generating starting polymer structures for molecular simulations in the dense phase. The work describes the ingredients of an algorithm for the creation of large, dense or diluted amorphous polymeric systems close to equilibrium and provides measures for its quality. The model systems are made of semiflexible (wormlike) repulsive multibead chains. The key feature of the method is its efficiency, in particular for large systems, while approaching given local and global chain characteristics. Its output has been proven to serve as an excellent basis for subsequent off-lattice molecular dynamics computer simulation. By combining chain growing… More >

Dongwoo Sheen¹, Sangwon Seo², Jinwoo Cho³

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.1, pp. 21-30, 2003, DOI:10.3970/cmes.2003.004.021

Abstract The reconstructing optimal microstructures of given homogenized coefficients of steady diffusion equation is studied. In the reconstruction, the governing equation of level set function is approximated by adding viscosity term and the numerical procedure for the evolution of the level set function for the solution is examined. The numerical experiments of reconstruction are obtained by applying a finite element method with locally fitted mesh. More >

M.A. Golberg¹, C.S. Chen²

CMES-Computer Modeling in Engineering & Sciences, Vol.2, No.1, pp. 87-96, 2001, DOI:10.3970/cmes.2001.002.087

Abstract The purpose of this paper is to develop a highly efficient mesh-free method for solving nonlinear diffusion-reaction equations in R^d, d=2, 3. Using various time difference schemes, a given time-dependent problem can be reduced to solving a series of inhomogeneous Helmholtz-type equations. The solution of these problems can then be further reduced to evaluating particular solutions and the solution of related homogeneous equations. Recently, radial basis functions have been successfully implemented to evaluate particular solutions for Possion-type equations. A more general approach has been developed in extending this capability to obtain particular solutions for Helmholtz-type equations by using polyharmonic spline… More >

A. Khechiba¹, Y. Benakcha¹, A. Ghezal¹, P. Spetiri²

FDMP-Fluid Dynamics & Materials Processing, Vol.14, No.2, pp. 137-154, 2018, DOI: 10.3970/fdmp.2018.04054

Abstract This work investigates the dynamic behavior of a pulsatile flow electrically conducting through porous medium in a cylindrical conduit under the influence of a magnetic field. The imposed magnetic field is assumed to be uniform and constant. An exact solution of the equations governing magneto hydro-dynamics (MHD) flow in a conduit has been obtained in the form of Bessel functions. The analytical study has been used to establish an expression between the Hartmann number, Darcy number and the stress coefficient. The numerical method is based on an implicit finite difference time marching scheme using the Thomas algorithm and Gauss Seidel… More >

Kentaro Doi^1,2, Yuzuru Chikasako¹, Satoyuki Kawano^1,3

FDMP-Fluid Dynamics & Materials Processing, Vol.11, No.1, pp. 1-26, 2015, DOI:10.3970/fdmp.2015.011.001

Abstract Propylene carbonate (PC) and ethylene carbonate are known as good candidates of organic solvents to be used in Li-ion rechargeable batteries, since Li⁺ ions exhibit preferable charge-discharge characteristics with such solvents. On the other hand, polar solvents usually form solvation shells with solute ions, and cause a drastic reduction of ionic conductivity. Along these lines, there has been a curious question why the diffusion coefficient D_Li of Li⁺ strongly depends on the salt concentration. In the present study, a theoretical model is developed on the basis of the Langevin equation in which the interactions between ions and solvent molecules are… More >

J.R. Lin¹, L.M. Chu², T.L. Chou³, L.J. Liang³, P.Y. Wang³

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.2, pp. 163-177, 2014, DOI:10.3970/fdmp.2014.010.163

Abstract We investigate the influence of non-Newtonian micropolar fluids on the dynamic characteristics of wide tapered-land slider bearings. The study is carried out on the basis of the micro-continuum theory originally developed by Eringen (1966). Analytical expressions for the linear dynamic coefficients are provided and compared with earlier results in the literature. In particular, direct comparison with the Newtonian fluid-lubricated tapered-land bearings by Lin et al. (2006) indicates that the use of non-Newtonian micropolar fluids can lead to a significant increase in the values of stiffness and damping coefficients. Such improvements are found to be even more pronounced for larger values… More >

L. Bennamoun¹, A. Belhamri², A. Ali Mohamed

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.2, pp. 177-192, 2009, DOI:10.3970/fdmp.2009.005.177

Abstract This study focuses on the interplay between drying kinetics (encountered in typical industrial processes and particularly in the context of solar drying) and the possible variation of external (e.g., environmental) conditions. Theoretical models of these behaviours are introduced. Experimental results confirmed by simulation are also presented. Variation of the thermo physical properties of air is taken into account in terms of variation of viscosity, density and coefficient of diffusion. In particular, this coefficient is calculated from experimental data and expressed as a function of the wet bulb air temperature. When external conditions are modified and, as a natural consequence, also… More >

D. Cherrared¹, E. G. Filali¹

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.2, pp. 127-151, 2013, DOI:10.3970/fdmp.2013.009.127

Abstract Our study deals with the characterization of the flow and related heat transfer in a smooth, circular minichannel. A duct with a sudden (sharp-edged) contraction is also considered. Prediction of the pressure loss coefficient in this case is obtained via the commercial code CFX 5.7.1. This code is based on the finite volume method for the solution of the Navier-Stokes and offers several turbulences models (in this study we use the shear stress turbulence model - SST). The numerical results are compared with experimental results obtained for a configuration similar to those considered in the numerical study. The numerical algorithm… More >