Study on Effects of Prandtl Number on Cross Buoyancy Flow past a Square Cylinder using OpenFOAM

The influence of Prandtl number on laminar, unsteady flow past a heated square cylinder placed in a free-stream has been studied computationally. The flow has been investigated for 0.02 < Pr < 100 at Re = 100 and Ri = 1. Effects of Prandtl number in unsteady mixed convection flow have been reported for the first time in the present study. The finite-volume based open source code OpenFOAM was used for the numerical simulations. An efficient algorithm (PIMPLE) has been used for the pressure-velocity coupling. Streamlines, isotherms, vorticity production and force coefficients have been studied in detail. The role of buoyancy on the baroclinic production has been discussed. Variation of lift coefficient with Pr was found to be quite interesting. The mean lift coefficient was found to be negative at low values of Pr but surprisingly it became positive at very high values of Pr.