Effect of thermal buoyancy on a fluid flowing past a pair of side-by-side square bluff-bodies in a low-Reynolds number flow regime

Abstract

In this research article, we have analyzed the effect of thermal stratification of shear layers due to mixed convection heat transfer past a pair of side-by-side square cylinders in a confined domain, an extended part of our recent study [A. Sanyal and A. Dhiman, “Wake interactions in a fluid flow past a pair of side-by-side square cylinders in presence of mixed convection,” Phys. Fluids 29, 103602 (2017)]. Investigations from the studies of instantaneous and time-averaged isotherms revealed the actual stretches of the temperature gradient in streamwise and transverse extents at Re = 1–40, Ri = 0–1, s/d = 0.7–10, and Pr = 50. The effects of “baroclinic production,” embedded in the transport of vorticity, were rigorously analyzed through the determination of local period-averaged vorticity flux at a certain cross section in the near-field downstream. The study also revealed the underlying flow physics pertaining to the variations in period-averaged wall vorticity and the local Nusselt number. The transport of vorticity has been explained in terms of the vortex structure formulations, and because of the absence of any such similar studies for multiple bluff-body arrangements, the study has been thoroughly correlated from the cases of single bluff-body flow. In an attempt to control several flow regimes by slightly changing the flow and thermal parameters, it is found that chaotic flow cannot exist beyond a certain value of s/d. However, an abnormality was noted in terms of the flow bifurcations at s/d = 1.5 at the juncture of flow transition from unseparated to a separated steady flow for the first time and this is solely attributed to the effect of thermal buoyancy in the flow field.