Transient natural convection in porous square cavity heated and cooled on adjacent walls

Transient natural convection in a square cavity filled with a porous medium is studied numerically. The cavity is assumed heated from one vertical wall and cooled at the top, while the other walls are kept adiabatic. The governing equations are solved numerically by a finite difference method. The effects of Rayleigh number on the initial transient state up to the steady state are investigated for Rayleigh number ranging from 10 to 2 10 2. The evolutions of flow patterns and temperature distributions were presented for Rayleigh numbers, Ra= 10 2 and 10 3. It is observed that the time taken to reach the steady state is longer for low Rayleigh number and shorter for high Rayleigh number.