MAXIMUM DENSITY EFFECTS ON NATURAL-CONVECTION IN A VERTICAL ANNULUS FILLED WITH A NON-DARCY POROUS-MEDIUM

This article numerically studies the problem of natural convection in a porous medium saturated with cold water, under density inversion, wi thin a vertical annulus. In modeling the flow in the porous medium the non-Darcy effects, which include the Forchheimer inertia and Brinkman viscous effects are taken into account. The governing equations are s olved numerically by the finite difference method using the modified s trongly implicit procedure. The effects of the inversion parameter The ta(m), radius ratio R, aspect ratio AR, Forchheimer inertia parameter Fc/Pr, and Darcy number parameter Da on the heat transfer and fluid f low characteristics are discussed in detail. Results show that both th e inversion parameter and radius ratio have a significant influence on the flow structure and heat transfer rate in the annulus. It is also found that the mean Nusselt number decreases as the Forchheimer inerti a parameter or the Darcy number increases. Moreover, the results obtai ned here are also compared and favorably agree with numerical results and with experimental data.