Grey Area Mitigation for Detached-Eddy Simulations Using Volume Forcing
Résumé
Hybrid RANS/LES (HRL) models use LES in complex regions and RANS otherwise. However, HRL models have issues when dealing with the transition between RANS and LES areas. The goal of this paper is to propose a solution to the lack of a mechanism in the DES model for transferring the modelled turbulent kinetic energy (TKE) to the resolved scales. The presented approach uses a volume forcing which amplifies existing velocity fluctuations. It aims at compensating for the modelled TKE dissipated by reinjecting it as resolved kinetic energy, so that the total TKE is unaffected. This solution's effectiveness is evaluated on a turbulent boundary layer over a flat plate, a case where DES is highly sensitive to mesh refinement. Different meshes and time steps are tested to assess the impact of the method on the flow. This approach shows a clear improvement on the turbulent quantities compared to the DES model.
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