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

Abstract

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 (10 ≤ Ra ≤ 10) 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≤ Ra≤10 and 71% at Ra=500, 1000≤ Ra≤10 for S=1 ) and ( 90% at Ra=100 , Ra=10 and 0.2≤S≤0.6 and 80% at Ra=500 , Ra=10 for 0.2≤S≤0.6 ). 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.