A hybrid RANS/LES calculation of turbulent channel flow

LES of wall-bounded flows with the no-slip boundary conditions is limited to moderate Reynolds numbers; wall modeling is necessary for high-Reynolds-number flows. One of approaches to better wall modeling is the hybrid RANS/LES modeling. In this study a hybrid modeling is applied to a channel flow calculation; the kappa-epsilon RANS model is used near the wall whereas the one-equation subgrid-scale model is adopted for the LES away from the wall. A mismatch of the mean velocity profile appears between the RANS and LES regions. To improve the velocity profile two values of the velocity component are defined at the boundary between the two regions. As a result the mismatch is removed and better velocity profiles are obtained.