The PANS k − ε model in a zonal hybrid RANS-LES formulation

A new approach to use the partially averaged Navier-Stokes (PANS) model as a hybrid RANS-LES model is presented. It is evaluated in fully developed channel flow and embedded LES in a hump flow. For the channel flow, the two RANS-LES interfaces are parallel to the walls. In the URANS region, fk is set to one. In the LES region, fk is set to a constant value (the baseline value is fk = 0.4) or it is computed. It is found that the new model gives good results for channel flow for a large span of Reynolds numbers (4 000 ≤ Reτ ≤ 32 000). In the channel flow simulations, three different grids are used in the wall-parallel planes, 322, 642 and 1282, and the model yields virtually grid-independent flow fields and turbulent viscosities. Embedded LES is used for the hump flow which is well predicted. The RANS-LES interface is normal to the flow from the inlet. RANS is used upstream of the interface. Downstream this interface, RANS is used near the wall and LES is used away from the wall