Analysis of LES models in Stratified Flows

Hybrid RANS/LES (Reynolds Averaged Navier Stokes/Large Eddy Simulation) simulations of complex turbulent flows, such as those found in the simulation of wind farms, are reliant on the underlying physical assumptions of the RANS and LES models that are used in the hybridization. To improve the accuracy of these simulations, development of improved SGS (subgrid) models that perform well in the anisotropic turbulence found in stratified flows are desired.

Through comparisons to data from direct numerical simulations (DNS) of stratified homogenous turbulence and benchmark LES simulations of stratified flows, we study the ability of various SGS models to accurately represent the flow dynamics. The importance of both the subgrid stress tensor and the subgrid scalar flux are investigated. With a focus on the use of a tensorial eddy viscosity, we discuss the path forward to a suitable LES model for hybrid simulations of wind farms.