Turbulent channel with slip boundaries as a benchmark for subgrid-scale models in LES

Most turbulent flows cannot be calculated by direct numerical simulation (DNS) of the Navier-Stokes equations because the range of scales of motion is so large that the computational cost becomes prohibitive. In large-eddy simulations (LES), only the large eddies are resolved and the effect of the small scales on the larger ones is supplied through a subgrid-scale (SGS) model in order to overcome most of the computational cost. In this sense, the role of SGS models is to provide the missing large-scale Reynolds stresses that can not be resolved in coarser LES computational grids.