LAUSR

Abstract An approach to extend the near-wall treatment approach of RANS turbulence models using wall functions for rough surfaces is proposed. The formulation is consistent with the low-Reynolds number turbulence model roughness extension, leading to reduced near-wall grid spacing dependence and accurate predictions for a large range of k s + / y + values. The formulation is further extended to the temperature wall functions and heat transfer prediction is assessed. The drawbacks of using the Reynolds analogy assumption are highlighted and three thermal corrections to improve these drawbacks are also examined. In particular, the correction term by Aupoix (2015), which accounts for the effect of the wetted surface area, is incorporated in the wall function formulation. This correction term significantly improves predictions as compared to the other two thermal correction terms at the expense of adding an additional physical parameter.