MIXED CONVECTION FROM A PAIR OF SIDE-BY-SIDE HEATED CIRCULAR CYLINDERS IN VERTICAL CONFIGURATION

Abstract

Mixed convection flow and heat transfer of non-Newtonian power-law fluids over a pair of side-by-side circular cylinders in aiding buoyancy are investigated numerically. The calculations are performed in an unconfined computational domain for the following range of physical parameters: Reynolds number (Re) = 1 - 40, Richardson number (Ri) = 0 - 1 and powerlaw index (n) = 0.2 - 1 for a transverse gap ratio of 1.5 at a constant Prandtl number (Pr) = 50. The extensive numerical results are presented; such as viscous, pressure and total drag coefficients, and average Nusselt number. The individual and overall drag coefficients decrease with Reynolds number and increase with Richardson number for all values of power-law index considered. The average Nusselt number increases with an increase in both Reynolds number and Richardson number, but decreases with increase in power-law index. It is observed that aiding buoyancy and shear-thinning tendency augment heat transfer characteristics. The maximum enhancement in heat transfer is found to be approximately 85% for Re = 40, n = 0.2 and Ri = 1. However, the maximum enhancement in the value of the average Nusselt number for Ri = 0 and 0.5 is found to be approximately 70% and 81% respectively. Finally, a simple heat transfer correlation is obtained for all the values of Re, n and Ri covered in this study.