Boundary Condition Effects on Laminar Natural Convection of Power-Law Fluids in a Square Enclosure Heated from below with Differentially Heated Horizontal Walls

Abstract

Two-dimensional steady-state laminar natural convection of power-law fluids in square enclosures with differentially heated horizontal walls (heated from below) subjected to constant wall temperature (CWT) and constant wall heat flux (CHWF) boundary conditions has been analyzed in detail based on computational simulations and a detailed scaling analysis. The effects of power-law exponent n ranging from 0.6 to 1.8 on the thermal transport have been investigated for nominal values of Rayleigh number in the range 103–105 and a Prandtl number range of 10–105. It is found that the mean Nusselt number Nu increases with increasing (decreasing) values of Rayleigh number (power-law exponent) for both CWT and CWHF configurations because of the strengthening of convective transport. In contrast, the mean Nusselt number Nu remains insensitive to changes in Prandtl number Pr in the range 10–105. It has been found that the Nu values for the CWHF configuration remain smaller than the corresponding values in the case ...