NUMERICAL INVESTIGATION OF NATURAL CONVECTION IN A POROUS ENCLOSURE WITH A FLUSH MOUNTED HEATER ON THE BOTTOM WALL

Abstract

In the present study, natural convection flows in a porous enclosure with a heater on the bottom wall have been investigated numerically. To change the heat transfer in the cavity, a heater is placed at different locations on the bottom wall of the cavity, while the top wall is considered to be cold and the vertical walls are kept adiabatic. The governing equations are obtained by applying the Brinkman extended Darcy flow Model and Boussinesq approximation to characterize heat flow paths along with the heat transfer rate. Finite element method is used to solve the dimensionless governing equations with the specified boundary conditions. The parameters leading the problem are the Rayleigh number (Ra), Darcy number (Da), Thermal conductivity ratio of porous media (k), Prandlt number (Pr), length and location of the heater. To observe the effects of the heater locations at various length of heater on natural convection in the cavity, three different locations of heater at bottom wall for various heater length with different values of Ra varying in the range 104 to 106 are considered. Simulated results are presented in terms of streamlines, isotherms and average Nusselt number at the hot wall in the cavity for the mentioned parameters. The results show that the length, locations of the heater and Rayleigh number have significant effect on the flow and thermal fields as well as the rate of heat transfer from the heated wall.