The PANS k–εk–ε model in a zonal hybrid RANS–LES formulation

• Evaluated in fully developed channel flow and embedded LES in a hump flow.
• fkfk is either constant or computed.
• For channel flow it gives good results for a large span of Reynolds numbers (4000⩽Reτ(4000⩽Reτ ⩽ 32,000).
• Three grids are used in the wall-parallel planes (322,642322,642 and 12821282); the model gives grid-independent results.
• The turbulent viscosity is also grid-independent (same on the three grids 322,642322,642 and 12821282).

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, fkfk is set to one. In the LES region, fkfk is set to a constant value (the baseline value is fk=0.4fk=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 (4000⩽Reτ4000⩽Reτ ⩽ 32,000). In the channel flow simulations, three different grids are used in the wall-parallel planes, 322,642322,642 and 12821282, 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.