Assessment of subgrid-scale modeling for large-eddy simulation of a spatially-evolving compressible turbulent boundary layer

- Assessment of the prediction quality of three popular SGS models.
- Near-wall asymptotic behaviour for supersonic turbulent boundary layer.
- Analysis of SGS dissipation, numerical scheme and mesh resolution.

The performance of three standard subgrid-scale (SGS) models, namely the wall-adapting local eddy-viscosity (WALE) model, the Dynamic Smagorinsky model (DSM) and the Coherent Structures model (CSM), are investigated in the case of a spatially-evolving supersonic turbulent boundary layer (STBL) over a flat plate at M∞=2 and Reθ ≈ 2600. A high-order split-centered scheme is used to discretize the convective fluxes of the Navier-Stokes equations, and is found to be highly effective to overcome the dissipative character of the standard shock-capturing WENO scheme. The consistency and the accuracy of the simulations are evaluated using direct numerical simulations taken from the literature. It is demonstrated that all SGS models require a comparable minimum grid refinement in order to capture accurately the near-wall turbulence. Overall, the models exhibit correct behavior when predicting the dynamic properties, but show different performances for the temperature distribution in the near-wall region even for cases with satisfactory energy resolution of more than 80%. For a well-resolved LES, the SGS dissipation due to the fluctuating velocity gradients is found to dominate the total SGS dissipation.