Unsteady Mixed Convection in a Vented Enclosure Partially Filled with Two Non-Darcian Porous Layers

Author: Moraga Nelson  

Publisher: Taylor & Francis Ltd

ISSN: 1521-0634

Source: Numerical Heat Transfer Part A: Applications, Vol.57, Iss.7, 2010-01, pp. : 473-495

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Abstract

Mixed convection in a ventilated rectangular cavity with a horizontal strip occupied by two media of different permeability is studied by using the finite-volume method. The effect of the parameters that govern the problem, the Reynolds number (200-500), the Richardson number (0.1-10), the Darcy number (1.E-6-1.E-2), permeability ratio (0.01-100), aspect ratio of the cavity (1-1.5), and direction of flow with or against gravity, is investigated. From the numerical results, the influence of Darcy and Reynolds numbers on the fluid mechanics can be inferred. When the cold fluid flow is descending, the fluid-porous medium heat transfer increases because the hotter fluid is located in the upper zones of the cavity. As the aspect ratio (height/width) increases from 0.67 to 1.5, both the Nusselt number (7.5 <>< 27) and="" the="" friction="" coefficient="" increase.="" the="" friction="" coefficient="" on="" the="" walls="" is="" greater="" when="" re =" 500" and="" ri =" 10" in="" the="" two="" directions="" of="" flow.="" as="" the="" darcy="" number="" increases,="" the="" velocity="" gradients="" increase="" near="" the="" walls,="" causing="" an="" increase="" of="" the="" friction="" coefficient="">< cf>< 47).>