Effect of Prandtl number on heat transfer from tandem square cylinders immersed in power-law fluids in the low Reynolds number regime

In this work, forced convection heat transfer from two square cylinders in tandem arrangement to power-law and Newtonian fluids has been investigated. The governing differential equations (continuity, momentum and energy balance) have been solved numerically. The results reported herein encompass wide ranges of the pertinent dimensionless parameters, namely, Prandtl number, 0.71 ⩽ Pr ⩽ 100, Reynolds number, 0.1 ⩽ Re ⩽ 40, power-law index, 0.2 ⩽ n ⩽ 1 and centre-to-center cylinder spacing, 2 ⩽ L/d ⩽ 6, albeit limited results were also obtained for L/d = 24 to retrieve the limiting case of non-interacting cylinders. The range of the center-to-center gap between the two cylinders is such that it corresponds to strong to virtually no interactions between the two cylinders. Furthermore, the range of Reynolds number is such that the flow is expected to be steady. The detailed heat transfer characteristics are interpreted in terms of the isotherm patterns in the close proximity of each cylinder and the variation of the local Nusselt number on the surface of each cylinder. Finally, the surface averaged values of the Nusselt number are expressed in terms of Reynolds number, power-law index and Prandtl number for center-to-center distances L/d = 2, 4 and 6. These results are also expressed in terms of the usual Colburn j-factor as a function of the Reynolds number and power-law index over the range of conditions spanned here.