On the Simulation of Turbulent Flows over Rough Walls Using the RANS Equations

The simulation of turbulent flows over rough walls remains one of the big challenges for computational fluid dynamics, Patel [1998]. For this type of flows, the most usual mathematical model used in engineering simulations is the Reynolds-averaged Navier-Stokes (RANS) equations using an equivalent sand-grain roughness height k_sg, see for example Aupoix [2014]. There are two main problems for the application of this approach to practical problems: the determination of the equivalent sand-grain roughness height k_sg and the incorporation of the effect of k_sg in the boundary conditions and equations of the turbulence model. This paper addresses the latter problem for three turbulence models: the Shear-Stress Transport version of the k−ω two-equation eddy-viscosity model, SST Menter et al. [2003]; the k−√kL two-equation eddy-viscosity model, KSKL Menter et al. [2006] and the SSG/LRR-ω Reynolds-Stress model, RSM Eisfeld and Brodersen [2005].