A. M. Ben-Arous¹, A. A. Busedra¹

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.4, pp. 255-262, 2008, DOI:10.3970/fdmp.2008.004.255

Abstract The problem of combined free and forced convection in horizontal semicircular ducts (flat wall at the bottom) with radial internal fins is investigated from a numerical point of view. The wall of the duct is assumed to have a uniform heat input along the axial direction with a uniform peripheral wall temperature (H1). The analysis focuses on the case of hydrodynamically and thermally fully-developed laminar flow. The governing equations for the velocity and temperature are solved by using a control-volume-based finite-difference approach. The fluid flow and heat transfer characteristics are found to be dependent on 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… 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 >

L. Bennamoun¹, A. Belhamri²

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.4, pp. 221-230, 2008, DOI:10.3970/fdmp.2008.004.221

Abstract This work focuses on tyipical heat and mass transfer phenomena during the processing of products in the context of the packed-bed drying method (products arranged in thick layers into dryers working in forced convection mode). The dryers are modeled as porous media at the macroscopic level. The simulations are carried out using the mass, momentum (written in the framework of the Darcy's law approximation) and energy equations applied for the different components. A diffusion model based on Fick's law is also used to take into account the drying kinetics. This approach allows monitoring of the 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 >

K. Achoubir¹, R. Bennacer², A. Cheddadi¹, M. El Ganaoui³, E. Semma^3,4

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.3, pp. 199-210, 2008, DOI:10.3970/fdmp.2008.004.199

Abstract The present work is devoted to the numerical investigation of the interaction between thermal and solutal convection in enclosures used for modeling directional solidification. The full transient Navier--Stokes, energy and species conservation equations are solved numerically by using finite volumes technique. More >

Sayavur I. Bakhtiyarov¹, Dennis A. Siginer²

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.3, pp. 163-184, 2008, DOI:10.3970/fdmp.2008.004.163

Abstract This article has no abstract. More >

Pravin Subramanian¹, Abdelfattah Zebib¹

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.3, pp. 139-162, 2008, DOI:10.3970/fdmp.2008.004.139

Abstract A theoretical and computational study of solutocapillary driven Marangoni instabilities in small spherical shells is presented. The shells contain a binary fluid with an evaporating solvent. The viscosity is a strong function of the solvent concentration, the inner surface of the shell is assumed impermeable and stress free, while non-linear boundary conditions are modeled and prescribed at the receding outer boundary. A time-dependent diffusive state is possible and may lose stability through the Marangoni mechanism due to surface tension dependence on solvent concentration (buoyant forces are negligible in this micro-scale problem). The Capillary number (Ca) provides More >

I. Ueno¹, T. Kishida²

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.1, pp. 55-60, 2008, DOI:10.3970/fdmp.2008.004.055

Abstract Phenomenon known as `tears of wine' arises on an inclined plate partially submerged in a bulk of alcohol-water mixture. This phenomenon apparently exhibits a periodic ordered structure, the flow field itself evolves quite complex feature; especially in the vicinity of the tear. In the present study, the authors paid their special attention to this unique, complex flow field of O(1 mm) with deformable surface. The flow pattern and the spatio-temporal particle behavior in the tear were reconstructed by applying three-dimensional particle tracking velocimetry (3-D PTV). More >