Natural convection heat transfer in an inclined porous cavity under time-periodic boundary conditions with positive/negative inclined angles

The unsteady natural convection in an inclined porous cavity with positive or negative inclined angles is studied numerically for the sinusoidal oscillating wall temperature on one side wall and constant average temperature on the opposing side wall. This system has no temperature difference between the opposing two side walls in a time-averaged sense, as studied by Kalabin et al. for a square enclosure. The flow field is modeled using the Brinkman-extended Darcy model. The effects of positive/negative inclined angles of the enclosure and oscillation frequency of wall temperature are studied for Ra 106, Da 10-3, 0.6, and Pr 1. The results demonstrate that the direction of heat flux is always from the lower side wall toward the upper side wall irrespective of the angles of inclination being positive or negative.