Assessment of LES techniques for mitigating the Grey Area in DDES models

The slow RANS-LES transition is a well-known shortcoming in hybrid turbulence models such as DelayedDetached Eddy Simulation (DDES). The present work assesses the feasibility of 2D sensitive LES models for naturally triggering turbulence, rather than using the specifically designed techniques available in the literature. This research has been carried out with OpenFOAM, which has been used for simulating the flow in a Backward-Facing Step configuration. The results have been compared with a DNS data set, showing the good mitigation capabilities of such LES techniques. Nevertheless, other cases should be studied before extracting any relevant conclusion.