Abstract: Three dimensional unsteady natural convective heat transfer in an inclined cubic enclosure with porous medium is studied numerically. The right side wall (X=1) of the enclosure is kept at a constant temperature of T_o, Temperature of the opposite vertical wall (X=0) varies by sine law with a mean value of T_o. Other walls are kept adiabatic. A Brinkman-extended Darcy model is used to describe flow through porous medium in the enclosure and the equations are solved with SIMPLE algorithm. Inclination angle α1 rotating around Y coordinate varies between 0å and 90°. Inclination angle α2 rotating around X coordinate varies between 0° and 45°. Dimensionless temperature oscillation frequency f ranges from 5° to 90π. Effects of inclination angles and temperature oscillation frequency on heat transfer are studied in detail. It shows that the maximal heat transfer is achieved at an inclined angles α1=46°, α2=45° and a temperature oscillating frequency f=45π.

Key words: time-periodic boundary conditions, porous medium, natural convection, three-dimensional numerical simulation