FULLY-DEVELOPED MIXED CONVECTION IN A HORIZONTAL CHANNEL HEATED UNIFORMLY FROM ABOVE AND BELOW

Calculations were performed for fully developed, laminar, mixed convection flow in a horizontal, parallel plate channel heated uniformly at the top and bottom plates. Spanwise conduction within the plates was considered, and calculations were performed for Pr -0.7, 0 < Ra* < 2.5 x 10*, and values of a nondimensionat conductance ratio in the range 10-s < y < IO3. It is shown that mixed convection heat transfer enhancement is restricted to the lower surface and that the attendant secondary flow induces large spanwise surface temperature variations for which the maximum temperature exceeds values associated with the upper surface. Increased conduction within the bottom plate weakens the secondary flow and decreases spanwise temperature variations. Results of the calculations have important implications in situations for which there is interest in maintaining reduced temperatures, as well as large heat transfer enhancement, at the bottom plate. © 1990 Taylor & Francis Group, LLC.