Forced Convection in Cross Flow of Power Law Fluids Over a Pair of Circular Cylinder in Tandem Arrangement

Forced convection heat transfer characteristics for the flow of incompressible power law fluids over a pair of cylinders (of equal diameters) in tandem arrangement have been studied numerically in the two-dimensional, steady cross-flow regime. The field equations have been solved using a finite volume method based solver (FLUENT 6.2) over the ranges of conditions as follows: power law index (n = 0.4, 1, 1.8), Reynolds number (Re = 1, 40), Prandtl number (Pr = 1, 100), the gap between the two cylinders (G = 2) and for two thermal boundary conditions, namely constant temperature or heat flux prescribed on the surface of the two cylinders. While the upstream cylinder shows heat transfer characteristics similar to that of an isolated cylinder, the downstream cylinder displays a complex dependence on the relevant dimensionless parameters. Both the wake interference and power-law rheology influence the heat transfer characteristics to varying extents. Generally, the upstream cylinder shows higher values of the average Nusselt number than the downstream cylinder. However, the average Nusselt number values for both cylinders are seen to be smaller than that for a single cylinder otherwise under identical conditions. With reference to Newtonian fluids, the shear-thinning behaviour promotes heat transfer whereas shear-thickening lowers it.