Assessment of wall models for coarse-mesh RANS simulations

In the present article, the applicability and accuracy of different boundary conditions for the simulation of turbulent, single-phase flows with heat transfer were assessed within the context of coarse-mesh CFD simulations for engineering applications. Standard wall functions for relevant turbulent quantities were extended to include geometry-dependent effects and implemented as boundary conditions for existing OpenFOAM solvers, along with a set of coarse-mesh wall models based on empirical correlations. The different models were tested in the simulation of numerical experiments where high-fidelity simulations can be provided and, in general, results show that the application of the new set of boundary conditions produces a satisfactory prediction of the streamwise velocity and temperature in the evaluated conditions, even when the first cell center is far from the wall. The analyzed extensions and corrections produce a better balance between accuracy and computational speed for coarse discretization, compared to traditional wall treatments.