A DDES Model with Subgrid-scale Eddy Viscosity for Turbulent Flow

Abstract

The original (delayed) detached-eddy simulation ((D)DES), a widely used and efficient hybrid turbulence method, is confronted with some flaws containing grid-induced separation (GIS), log-layer mismatch (LLM), and slow RANS-LES transition. A novel hybrid turbulence model, namely production-limited eddy simulation (PLES), depleting the production through introducing the subarid-scale eddy viscosity is proposed. The simulation data of the zero-pressure gradient boundary layer proves that a good performance in mitigating the GIS issue is obtained from the PLES model. The results of the channel flows reveal that the PLES model has eliminated the LLM of the velocity. A good conformity is given for the backward-facing step flow in the PLES simulation, which proves that the PLES model is validated for complex flow. More turbulent scales in the shear layer are captured by the PLES model, which testifies that the PLES model has a faster RANS/LES switch than the IDDES model. The PLES model has a good performance in predicting the cylinder flow with coarser grid resolution. Due to the new LES mode, the PLES model behaves better than the IDDES model in simulating the cylinder flow. Furthermore, the PLES model allows one to use different LES model in the LES portion for other complex flows.