Mixed Convection in an Enclosure with Different Inlet and Exit Configurations

A numerical analysis is carried out to study the performance of mixed convection in a rectangular enclosure. Four different placement configurations of the inlet and outlet openings were considered. A constant flux heat source strip is flush-mounted on the vertical surface, modeling an integrated circuit chips affixed to a printed circuit board, and the fluid considered is air. The numerical scheme is based on the finite element method adapted to triangular non-uniform mesh elements by a non-linear parametric solution algorithm. Results are obtained for a range of Richardson number from 0 to 10 at Pr = 0.71 and Re = 100 with constant physical properties. At the outlet of the computational domain a convective boundary condition (CBC) is used. The results indicate that the average Nusselt number and the dimensionless surface temperature on the heat source strongly depend on the positioning of the inlet and outlet. The basic nature of the resulting interaction between the forced external air stream and the buoyancy-driven flow by the heat source is explained by the heat transfer coefficient and the patterns of the streamlines, velocity vectors and isotherms.