Papers by Author: K. Bouhadef

Abstract: This paper presents a numerical study of mixed convection heat and mass transfer in horizontal rectangular channels partially filled with porous medium. The main contribution of this research is to characterize how the porous block will create a heterogeneity that will induce a change on the Poiseuille-Rayleigh-Benard (PRB) fluid circulation dynamics. For a broad range of dimensionless parameters, which control the mixed convection, we show that the effect of the insertion of the porous block changes the thermal and solutal boundary layers; we find that the exchanges are intensified near the sidewalls in the porous region compared to upstream and downstream of the porous medium; and inversely in the core region. We describe, also, the onset of the longitudinal rolls at both upstream and downstream of the porous region. And finally, we compared the heat transfer, for different positioning of the porous medium with the purely fluid mixed convection.

Abstract: A two dimensional mathematical model has been developed to simulate the coupled heat and mass transfer in a porous medium undergoing a strong exothermic reaction. The problem has received a lot of interest due to its relevance in a wide variety of engineering applications such heat pipes, nuclear reactors, drying technologies, catalytic reactors and others. The fluid flow is modelled via the Darcy-Brinkman-Forchheimer equation. This model is solved numerically by the finite volume method, and the code is validated by comparing with previously published works. The influence of the exothermic chemical reaction on the heat and mass transfer in the porous medium is discussed. The effects of pertinent parameters such as the Biot number, the Reynolds number and the Frank-Kamenetskii number were analyzed. Quantitative and qualitative results are presented. Comparisons with other works in the literature are performed and excellent agreement between the results is obtained.

Abstract: The contribution of this work is to characterize the travelling wave’s appearance and to generalize the behavior of Poiseuille-Rayleigh-Benard (PRB) systems for a broad range of dimensionless parameters, which control the double diffusive mixed convection. The numerical results consist to analyzing the flow regimes of the steady longitudinal thermoconvectives rolls for the case of purely thermal mixed convection and for both thermal and mass diffusion. The passage from an opposed volume forces to cooperating one at fixed Rayleigh (Ra), Reynolds (Re) and Lewis (Le) numbers, affects considerably the birth and the development of the longitudinal rolls R//. The distribution of the heat and mass transfer, presented by the average Nusselt and Sherwood numbers, is also examined.

Abstract: The problem of unsteady natural convection heat transfer in a vertical opened porous cylinder submitted to a sinusoidal time variation temperature on the lateral wall has been investigated numerically. The widely used Darcy flow model without flow establishment at the cylinder exit has been used. In the case of constant wall temperature, two types of flows were obtained, with and without fluid recirculation, depending on the filtration Rayleigh number (Ra), the aspect ratio (A) and the Biot number (Bi) have been obtained. The obtained heat transfer, in case of low dimensionless oscillations amplitude (XA<0.5), shows a non significant enhancement (less than 5%) in comparison to the constant wall temperature case.