V. Haslavsky, E. Miroshnichenko, E. Kit, A. Yu. Gelfgat

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.3, pp. 209-234, 2013, DOI:10.3970/fdmp.2013.009.209

Abstract Experimental and numerical observations of oscillatory instability of melt flow in a Czochralski model are compared, and a disagreement observed at small crystal dummy rotation rates is addressed. To exclude uncertainties connected with flow along the free surface, the latter is covered by a no-slip thermally insulating ring. Experiments reveal an appearance of oscillations at temperature differences smaller than the numerically predicted critical ones. At the same time, a steep increase of the oscillations amplitude is observed just beyond the computed threshold values. By increasing the dummy rotation gradually, we are able to qualitatively confirm the numerically predicted flow destabilization.… More >

A. Rtibi¹, M. Hasnaoui¹, A. Amahmid¹

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.2, pp. 183-207, 2013, DOI:10.3970/fdmp.2013.009.183

Abstract In this paper we present an analytical and numerical study of Soret convection in an inclined rectangular porous layer saturated with a binary fluid and subject to uniform heat fluxes. In the problem formulation, the Darcy model is considered and the results are presented for wide ranges of R_T (50 ≤ R_T ≤ 1000), θ(0°≤θ≤180°) and φ(-1 ≤ φ ≤ 1) for Le = 10, where R_T, θ, φ, and Le are the thermal Darcy-Rayleigh number, the cavity inclination, the separation parameter, and the Lewis number, respectively. An analytical solution, derived on the basis of the parallel flow approximation, is… More >

E. A. El-Abeedy¹, A. A. Busedra¹

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.2, pp. 153-167, 2013, DOI:10.3970/fdmp.2013.009.153

Abstract Fully developed laminar mixed convection in inclined semicircular ducts is investigated numerically for the specific case of uniform heat input along the axial direction and uniform peripheral wall temperature, H1. The duct is considered over a variety of orientations (rotations) of its cross section, ranging from 0° (flat wall horizontally facing upward) to 180° (flat wall horizontally facing downward) with increment of 45° and a fixed inclination of its axis (with respect to the direction of gravity). In particular, the following conditions are considered: inclination α = 20°, 300 ≤ Re ≤ 1000, Pr = 4 and Gr = 1… More >

A. Maougal¹, R. Bessaïh²

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.1, pp. 35-59, 2013, DOI:10.3970/fdmp.2013.009.035

Abstract The present study is a numerical investigation of the irreversibility and heat transfer properties of a steady laminar mixed flow in a square cavity, filled with a saturated porous medium and heated by a discrete set of heat sources. The continuity, Navier-Stokes, energy and entropy generation equations have been solved by a finite volume method. Both heat transfer irreversibility and fluid friction irreversibility have been taken into account in the computations of entropy generation. Simulations have bee carried out for Reynolds number Re=20, 40, 80, 100, 200, Darcy number, Da=10^-5-10^-1, Prandtl number, Pr=0.015, 0.7, 10, 103, and aspect ratio, D/H… More >

M. M. Shemirani¹, M. Z. Saghir²

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.1, pp. 11-21, 2013, DOI:10.3970/fdmp.2013.009.011

Abstract Producing homogeneous single bulk crystals requires a good understanding of the thermo-solutal behavior in the solvent region. This study explores simulation of the growth of large diameter single bulk crystals of silicon and germanium alloy from its melt utilizing Bridgman method. Both thermal and solutal diffusion of silicon and germanium in the molten SiGe alloy are of interest. It was observed that the diffusion dominates the transport phenomenon in the solvent region especially in the first 25 mm of the model due to having a Pe_T <<1. It was also found that the control of both radial and axial applied… More >

Walid Hassen¹, Mohamed Naceur Borjini², Habib Ben Aissia¹

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.4, pp. 381-396, 2012, DOI:10.3970/fdmp.2012.008.381

Abstract In this work we consider the problem related to the electro-thermo-convection of a dielectric fluid in a rectangular enclosure placed between two electrodes. This layer is subjected simultaneously to the injection of electric charges and to a thermal gradient. The influence of the electric Rayleigh number (200 - 1000) on the structure of the flow, the density of electric charge and heat transfer is investigated. An oscillatory flow is observed and discussed in detail. More >

F.Z. Ferahta^1,2, S. Bougoul¹, M. Médale², C. Abid²

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.3, pp. 339-352, 2012, DOI:10.3970/fdmp.2012.008.339

Abstract A numerical study is carried out to evaluate the thermal performances of a solar collector. As it is well known, that the thermal losses of such systems are mainly of a convective nature, the study is concentrated in particular on the features of natural convection that is activated in the air domain delimited by the upper glass and the lower absorber of the solar collector. The efficiency of such a system depends essentially on both the temperature difference and the distance between the absorber and the glass. Since the temperature difference remains an uncontrolled variable (because it depends on the… More >

Nadia Dihmani¹, Samir Amraqui¹, Ahmed Mezrhab^1,2, Najib Laraqi³

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.3, pp. 311-322, 2012, DOI:10.3970/fdmp.2012.008.311

Abstract Natural convection with surface radiation heat transfer is investigated numerically in a vented vertical channel heated asymmetrically. The numerical solution is obtained using a finite volume method based on the SIMPLER algorithm for the treatment of velocity-pressure coupling. Concerning the radiation exchange, in particular, the working fluid is assumed to be transparent, so that only the solid surfaces (assumed diffuse-grey) give a contribute to such exchange. The effect of Rayleigh numbers and rib width (for Pr=0.7 air fluid) on the heat transfer and flow structure in the channel is examined in detail. Results are presented in terms of isotherms, streamlines,… More >

Y. Amirouche¹, R. Bessaïh²

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.3, pp. 295-310, 2012, DOI:10.3970/fdmp.2012.008.295

Abstract This paper summarizes a series of computational results originating from the simulation of three-dimensional turbulent natural convection occurring in a vertical channel containing 5 cubic aluminum heated sources (mimicking a set of electronics components equally spaced in the vertical direction). A three-dimensional, conjugate heat transfer model with appropriate boundary conditions is used. In particular, the governing equations are solved by a finite volume method throughout the entire physical domain. Calculations are made for distinct values of: the Rayleigh number, the ratio (air/solid) of thermal conductivities and other geometrical parameters (in order to examine the influence of such variables on the… More >

A. Arid¹, T. Kousksou¹, S.Jegadheeswaran², A. Jamil³, Y. Zeraouli¹

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.3, pp. 257-276, 2012, DOI:10.3970/fdmp.2012.008.257

Abstract A two-dimensional numerical model has been developed to investigate the phase-change of ice near 4 °C in a rectangular cavity. The enthalpy-porosity model is reformulated in terms of conservation equations of mass, momentum and heat to account for the evolution the solid/liquid interface. Constant and time-dependent (with sinusoidal law) temperature boundary conditions are considered. Results confirm the possibility to control the typical dynamics of ice melting in a square cavity near the density inversion point by means of a wall temperature which varies in time (with given amplitude and frequency). More >