Transient free convection in a square cavity filled with a porous medium

Transient free convection in a two-dimensional square cavity filled with a porous medium is numerically studied in this paper. The left vertical wall is suddenly heated to a constant temperature Th, while the right wall is suddenly cooled to a constant temperature Tc by equal amount relative to an initially uniform temperature distribution. Both the horizontal walls are adiabatic. The finite volume numerical method is used to solve the non-dimensional governing equations. The results are obtained for the initial transient state up to the steady state, and for Rayleigh number values of 102–104. It is observed that the average Nusselt number showing an undershoot during the transient period and that the time required to reach the steady state is longer for low Rayleigh number and shorter for high Rayleigh number.