Transient natural convection in differentially heated porous enclosures (vol 3, pg 165, 2000)

Abstract

Transient natural convective flow and hear transfer in a differentially heated enclosure filled with a saturated porous medium is investigated numerically by adopting the general flow model that accounts for both the boundary and the inertial effects in porous media. The present study covers investigation of the fluid Rayleigh number (RA) between 1 x 10(5) and 1 x 10(9), the Darcy number (DA) of 1 x 10(-6) to 1 x 10(-2) for aspect ratio, and the inertial parameter and modified Prandtl number of unity. For DA > 1 x 10(-6), it is found that if the modified Rayleigh number (Ra-m = Ra.Da) is greater than tao. significant differences exist between the general model and the Darc? model predictions, especially at the early transient stage. Both in the Darcy and non-Darcy regimes. the Brinkman extended,model agreed well with the general model. Also, it is found that Forchheimer's term is significant in the transient stage, but it is of no importance at the steady state.