Partially Averaged Navier Stokes simulation of turbulent heat transfer from a square cylinder

A variable resolution modeling approach, namely the Partially-Averaged Navier Stokes (PANS) approach, is used to study heat transfer in a separated turbulent flow field. The simulations are performed to assess the applicability and effectiveness of the PANS approach. Two types of grids are compared: a structured grid with full hexahedral elements with wall functions model (SM-WF) and an unstructured grid with hybrid tetrahedral-prismatic elements with wall resolve model (UM-WR). A heated square cylinder in cross air stream at Re = 2.2 × 104 is considered and the simulations are performed using a finite volume based opensource software, OpenFOAM. It is observed that the PANS approach, with both the meshing strategies adopted, is able to predict the unsteady flow behavior around the cylinder and in the wake. But, only the wall resolve case reproduces the thermal and the Nusselt number behaviors around the cylinder as compared to experimental results. Further the wall resolve model is used to study the heat transfer phenomena at different faces of the cylinder over a complete vortex shedding cycle using the phase-averaged analysis of the shedding phenomenon. The turbulent heat fluxes are also studied to understand the effect of turbulence on convection.