E.J. Sellountos¹, A. Sequeira¹

CMES-Computer Modeling in Engineering & Sciences, Vol.23, No.2, pp. 127-148, 2008, DOI:10.3970/cmes.2008.023.127

Abstract In this work a hybrid velocity-vorticity scheme for the solution of the 2D Navier-Stokes equations is presented. The multi-region Local Boundary Integral Equation (LBIE) combined with Radial Basis Functions (RBF) interpolation is used for the solution of the kinematics and the multi-region BEM for the solution of the transport kinetics. The final system of equations is in band form for both methods. The issue of RBF discontinuities is resolved by constructing the RBF matrix locally in every region. The kinematics integral equation is used in three different forms, for coupling the velocity field on the More >

Nagalinga Rajan, Soumyendu Raha¹

CMES-Computer Modeling in Engineering & Sciences, Vol.23, No.2, pp. 91-116, 2008, DOI:10.3970/cmes.2008.023.091

Abstract The article describes a numerical method for time domain integration of noisy dynamical systems originating from engineering applications. The models are second order stochastic differential equations (SDE). The stochastic process forcing the dynamics is treated mainly as multiplicative noise involving a Wiener Process in the Itô sense. The developed numerical integration method is a drift implicit strong order 2.0 method. The method has user-selectable numerical dissipation properties that can be useful in dealing with both multiplicative noise and stiffness in a computationally efficient way. A generalized analysis of the method including the multiplicative noise is More >

Q.W. Ma¹

CMES-Computer Modeling in Engineering & Sciences, Vol.23, No.2, pp. 75-90, 2008, DOI:10.3970/cmes.2008.023.075

Abstract In the MLPG_R (Meshless Local Petrove-Galerkin based on Rankine source solution) method, one needs a meshless interpolation scheme for an unknown function to discretise the governing equation. The MLS (moving least square) method has been used for this purpose so far. The MLS method requires inverse of matrix or solution of a linear algebraic system and so is quite time-consuming. In this paper, a new scheme, called simplified finite difference interpolation (SFDI), is devised. This scheme is generally as accurate as the MLS method but does not need matrix inverse and consume less CPU time More >

L. Parussini¹, V. Pediroda²

CMES-Computer Modeling in Engineering & Sciences, Vol.23, No.1, pp. 29-52, 2008, DOI:10.3970/cmes.2008.023.029

Abstract In this paper different Polynomial Chaos methods coupled to Fictitious Domain approach have been applied to one- and two- dimensional elliptic problems with multi uncertain variables in order to compare the accuracy and convergence of the methodologies. Both intrusive and non-intrusive methods have been considered, with particular attention to their employment for quantification of geometric uncertainties. A Fictitious Domain approach with Least-Squares Spectral Element approximation has been employed for the analysis of differential problems with uncertain boundary domains. Its main advantage lies in the fact that only a Cartesian mesh, that represents the enclosure, needs More >

G. Accary¹, S. Meradji², D. Morvan², D. Fougère²

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.4, pp. 263-270, 2008, DOI:10.3970/fdmp.2008.004.263

Abstract In the literature, only few references have dealt with mixed-convection flows in the low Mach number approximation. For this reason, in the present study we propose to extend the standard 3D benchmark for mixed convection in a rectangular channel heated from below (Medale and Nicolas, 2005) to the case of large temperature variations (for which the Boussinesq approximation is no longer valid). The Navier-Stokes equations, obtained under the assumption of a low Mach number flow, are solved using a finite volume method. The results, corresponding to the steady-state case of the benchmark, lead to the More >

R. Henda¹, W. Quesnel², Z. Saghir³

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.4, pp. 237-244, 2008, DOI:10.3970/fdmp.2008.004.237

Abstract The transient thermal behavior of a two-dimensional circulating porous bed is analytically investigated. A one-energy equation model, representing both the gas and solid phases via a unified temperature, is employed to describe the thermal behavior of the circulating bed. The latter is essentially a tube and shell heat exchanger commonly used in technologically important applications. The model equation is transformed into a simpler set of partial differential equations using an analytical procedure. The analytical solution, based on the method of separation of variables and the principle of superposition, is formulated for the calculation of the More >

Munther Issa K,ah¹, Jean-Luc Meunier²

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.4, pp. 231-236, 2008, DOI:10.3970/fdmp.2008.004.231

Abstract Multi-walled carbon nanotubes (MWCNTs) have been produced by chemical vapor deposition using acetylene as a hydrocarbon source at 700 \textdegree C. The Monel substrates coated with MWCNTs can be used later as cathodes in the Physical Vapor Deposition (PVD) systems to produce CNTs embedded in diamond-like carbon (DLC) film. This new method of generating MWCNTs on Monel substrates without using any catalyst is very simple and uses very little power compared to other CNTs generating techniques. Embedded CNTs in a crystalline carbon coat was observed on mirror-like polished Monel substrates at 700 \textdegree C but More >

A.A. Ivanova¹, V.G. Kozlov^1,2,3, D.A. Polezhaev¹, D. Pareau³, M. Stambouli³

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.3, pp. 211-220, 2008, DOI:10.3970/fdmp.2008.004.211

Abstract The problem for the optimization of mass-transfer on the interface of two immiscible liquids by means of vibrational hydromechanics is studied experimentally. A new vibrational cell of Lewis's type expressly conceived for such purposes is described. Flow is generated by activators in the form of disks inducing translational axial oscillations near the opposite end faces of the cavity. It is shown that such vibrating disks can lead to the onset of a large-scale toroidal whirlwind effectively mixing the liquid throughout the volume. According to the experiments, in particular, axisymmetrical radial flows are generated on both More >

V. Shevtsova^1,2, A. Mialdun¹, C. Ferrera^1,4, M. Ermakov^3,4, J. M. Montanero⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.1, pp. 43-54, 2008, DOI:10.3970/fdmp.2008.004.043

Abstract Dynamic free surface deformations induced by buoyant and thermocapillary convection in liquid bridges of 5cSt silicone oil are studied experimentally and numerically. The experiments are performed in ground conditions and static deformation is unavoidable. Convective motion starts in the liquid bridge as soon as ΔT ≠ 0 and initially leads to a stationary dynamic deformation of the free surface. Oscillatory motion starts at a critical value of ΔT and causes oscillations of the interface. The final supercritical shape of the free surface is a result of the static shape with superimposed subcritical stationary and oscillatory dynamic deformations. More >

Shuwang Li¹, Xiangrong Li¹, John Lowengrub^1,2, Martin Glicksman³

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.1, pp. 27-42, 2008, DOI:10.3970/fdmp.2008.004.027

Abstract In this paper, we suggest a deterministic mechanism for the generation and development of side-branches in dendritic growth. The present authors investigated recently [Glicksman, Lowengrub, and Li (2006)] the existence of such a deterministic branching mechanism induced through the Gibbs-Thomson-Herring (GTH [Herring (1951)]) anisotropic capillary boundary condition. In this paper, we focus our study on an anisotropic kinetic boundary condition. We develop and apply accurate boundary integral methods in 2D and 3D, in which a time and space rescaling scheme is implemented, that are capable of separating the dynamics of growth from those of morphology More >