Investigation the natural convection heat transfer between two fluids inside square enclosure separated by thin plate

Fluid flow and heat transfer in a square enclosure diagonally divided by a conductive thin plate has been numerically investigated. The upper diagonal zone of the enclosure filled with a saturated porous medium while the subdiagonal zone of the enclosure filled with air as working fluids. The enclosure was heated partially from below and cold from upper surface isothermally while the two vertical surface are insulated. The governing equations are solved using finite difference methods. Results were obtained for different value of Rayleigh number (103 Ra 105) for air and different value of modified Rayleigh number (100 Ra* 500) for porous medium as well as different dimensionless length of the heated surface (0.2 , 0.4 , 0.5 and 0.6 ). The results show that the increasing in Rayleigh number in both sides of the enclosure (Ra* & Ra) causes increasing in the Nusselt number. The percentage increasing is approximately is (92% at Ra*=100, 1000 Ra105 and 71% at Ra*=500, 1000 Ra105 for S=1 ) and ( 90% at Ra*=100 , Ra=104 and 0.2S0.6 and 80% at Ra*=500 , Ra=104 for 0.2S0.6 ). The flow become multi-cellular in porous media side also the increasing in dimensionless length of the heated surface causes increasing in the Nusselt number.