The effect of modified Rayleigh number, positions and lengths of two
perpendicular heated surfaces on natural convection heat transfer was studied
numerically, where the two surfaces are embedded in square cavity filled with saturated
porous medium. All walls of the cavity are kept at constant temperature. Indirect
numerical method was used to solve the governing equations, which are: the nondimensional
Darcy flow equation as well as the non-dimensional energy equation, which
were solved numerically by finite difference method using Gauss-Seidel iteration
coupled with (Successive Under Relaxation) technique. This study covered a wide range
of modified Rayleigh number range (100-1000), nine positions and the ratios of length of
vertical surface to the horizontal (0.5,1, 2). It was found that the positions of two heated
surfaces have small effect on the heat transfer rate, but any increase in the length of two
surfaces leads to an increase in average Nusselt number, but an increase in the length of
vertical surface leads to more increase in the average Nusselt number