A PANS study of fluid flow and heat transfer from a square cylinder approaching a plane wall

Abstract

Simulations were carried out to study the forced convection from a heated square cylinder placed near a plane wall boundary in a channel. The parameters that were studied are Reynolds number (Re) and the distance between the cylinder and the plane wall (gap ratio). At higher Re, turbulence modeling was performed using a dynamic PANS approach along with wall resolving approach. Simulations were carried out using a finite volume based open source software, OpenFOAM. The cylinder was kept at a constant temperature such that the difference in temperature between the incoming velocity and cylinder was small enough to treat temperature as a scalar quantity. For Re = 22000 the critical value of the gap ratio was found to be 0.3 at which the vortex shedding was completely suppressed. The face averaged value of the Nusselt number for the back face dropped below the front face value for the gap ratio lower than 0.5. The effect of Re was also studied for the gap ratio of 0.4, and it was observed that up to Re = 1000, increase in total Nusselt number from the cylinder was linear but as the wake became unsteady and turbulent the Nusselt number increased exponentially with Re. Three different flow regimes were observed in terms of Re and are investigated in detail for the heat transfer associated with it.