NATURAL-CONVECTION IN A POROUS CAVITY SATURATED WITH A NON-NEWTONIAN FLUID

A numerical and theoretical study is performed to analyze the steady-s tate natural convection fluid flow and heat transfer in a rectangular porous cavity filled with a non-Newtonian fluid and bounded by imperme able surfaces. The flow is modeled by utilizing the modified Darcy equ ations. Isothermal boundary conditions are considered where two opposi te vertical walls are kept at constant but different temperatures, and the horizontal walls are insulated.:The external parameters are the A R, Ra, and power-law index. Employing pure Scaling arguments, four hea t transfer modes are identified: 1) pure conduction, 2) high-Ra :conve ction, 3) distinct horizontal Boundary-layer convection, and: 4) disti nct vertical boundary-layer convection. The results obtained from the scaling arguments are verified numerically. The agreement between the results obtained from the scaling arguments and the numerical model is good. The numerical results are presented in terms of theoretical str eamlines and isotherms, tile average Nu at the hot wall, the horizonta l velocity at the vertical midplane, the vertical velocity at the hori zontal midplane, and the temperature distribution at the horizontal an d the vertical midplanes.