Towards an Improved Wall Function Formulation for Reynolds‐Averaged Navier–Stokes Simulations of Turbulent Concentric Coaxial Pipe Flows

Concentric coaxial (annular) pipe flow is numerically investigated using a high Reynolds number (HRN) Reynolds‐Averaged Navier–Stokes (RANS) approach, given direct numerical simulation (DNS) boundary conditions. Previous work has shown that traditional wall models fail in predicting bulk quantities due to insufficient representation of the inner wall. The main objective is to assess the suitability of RANS for prediction of the flowfield if a wall function that captures the effect of the inner wall spanwise curvature at small radius ratios is provided. As a starting point, the mixing length model is used as the RANS turbulence model. The results suggest that while improved mean flow statistics can potentially be obtained, an accurate wall model representation is insufficient for capturing the mean flow in terms of the location of the velocity maximum properly.