Zonal k-l based large eddy simulations

Zonal k-l based large eddy simulation (LES) approaches are presented. To reduce computational demands, near walls, Reynolds averaged Navier-Stokes (RANS) like modelling is used. The interface location for the differing models is either explicitly specified, or, based on length scale compatibility, allowed to naturally locate. With the latter approach the location is strongly grid controlled. When explicitly specified (based on turbulence physics grounds), to enhance results length scale smoothing is implemented. Using standard established LES and RANS model constants the zonal methods are shown to reproduce a satisfactory law of the wall. The approaches are implemented in both cell-vertex and cell-centred codes with similar results being found. Various other sensitivity studies are performed. These show that, as with standard LES, predictions are most sensitive to filter definition, first off wall grid node normal positions and temporal scheme order. For a non-isothermal periodic ribbed channel, the new zonal LES predictions are found to be significantly more accurate than those for an established RANS model and also LES.