Time-averaged active model-splitting hybrid RANS/LES*

We discuss progress in the development and validation of a new approach for hybrid RANS/LES simulations.  Referred to as the time-averaged active model-splitting approach (TAMS) , it has been specifically constructed to overcome challenges associated with existing hybrid approaches related to LES/RANS blending techniques and inconsistencies between the resolved and modeled turbulence.  The new approach is based on a hybridization strategy in which the RANS and LES components act through separate models formulated using the mean and fluctuating velocity, respectively, as approximated by time averaging over the local turbulent timescales.  Further, resolved fluctuating turbulent energy is actively transferred from the modeled to the resolved scales in regions identified to be capable of resolving more turbulence. Finally, the model makes use of an anisotropic LES model that is intended to represent the effects of grid anisotropy with potential to directly account for grid heterogeneity as well. The approach is demonstrated on fully-developed, incompressible channel flow with encouraging results.