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

Transient natural convective flow and hear transfer in a differentially hea ted enclosure filled with a saturated porous medium is investigated numeric ally by adopting the general flow model that accounts for both the boundary and the inertial effects in porous media. The present study covers investi gation of the fluid Rayleigh number (RA) between 1 x 10(5) and 1 x 10(9), t he 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 great er than tao. significant differences exist between the general model and th e Darc? model predictions, especially at the early transient stage. Both in the Darcy and non-Darcy regimes. the Brinkman extended,model agreed well w ith the general model. Also, it is found that Forchheimer's term is signifi cant in the transient stage, but it is of no importance at the steady state .