Aiding-BuoyancyMixed Convection from a Pair of Side-by-Side Heated Circular Cylindersin Power-Law Fluids.

Mixed-convectionflow and heat transfer of non-Newtonian power-law fluids over a pairof side-by-side circular cylinders in aiding buoyancy are investigatednumerically. The calculations are performed in an unconfined domainfor the following range of physical control parameters: Reynolds number(Re) = 1–40, Richardson number (Ri) = 0–1, and power-law index (n) = 0.2–1for a transverse gap ratio of 1.5 at a constant Prandtl number (Pr) of 50. Extensive numerical results are presented, suchas viscous, pressure, and total drag coefficients, average Nusseltnumber, and transition from a steady to a time-periodic regime. Theoverall drag coefficient and its components decrease with the Reynoldsnumber and increase with the Richardson number for all values of thepower-law index considered. The average Nusselt number increases withan increase in both the Reynolds and Richardson numbers but decreaseswith an increase in the power-law index. It is observed that aidingbuoyancy and shear-thinning tendency augment heat-transfer characteristics.The maximum enhancement in heat transfer is found to be approximately85% for Re= 40, n= 0.2, and Ri= 1. However, the maximum enhancement in the value ofthe average Nusselt number for Ri= 0 and 0.5 isfound to be approximately 70% and 81%, respectively. Finally, a simpleheat-transfer correlation is obtained for the values of Re, n, and Ricovered in this study. [ABSTRACT FROM AUTHOR]