Performance of two equation turbulence models for prediction of flow and heat transfer over a wall mounted cube

This paper deals with the CFD predictions of the three dimensional incompressible flow over a wall mounted cubic obstacle placed in fully developed turbulent flow along with the heat transfer calculations. Reynolds number considered in this study is 1870 based on cube height, h and bulk velocity Ub. Our main objective is to find out the appropriate two equation turbulence model for the complex flow structure which involves recirculation, separation and reattachment. We have used standard k–ε, low-Reynolds number k–ε, non-linear k–ε model, standard k–ω and improved k–ω models to solve the closure problem. The non-linear k–ε model and improved k–ω models along with standard models are validated with bench mark problem – flow through a backward facing step (BFS). Results showed that the improved k–ω model is giving overall better predictions of the flow field especially recirculation zone, mean streamwise velocity, and turbulent characteristics when compared to those by standard eddy viscosity models. The non-linear k–ε model is giving better prediction when compared to standard k–ε and low Reynolds number k–ε models. The complex vortex structure around the cube causes large variation in the local convective heat transfer coefficient. The maximum of the heat transfer coefficient occurred in the proximity of the reattachment points and the minimum is found at the recirculation zone.