Comparative Analysis of Hybrid Turbulence Models

A numerical study was performed to evaluate two dynamic hybrid models (DHM). The two DHM's investigated are based upon Speziale's damping function and a function based on the turbulent kinetic energy spectrum. Each model computes a sub-filter turbulent viscosity defined by combining a local effective filter length scale with a standard two-equation turbulent viscosity formulation. The efficiency of the DHM is attributed to the dynamic calculation of the sub-filter cutoff length scale.

Evaluation of the hybrid turbulence models was performed by simulating backward facing step using three varying grid resolutions. All simulations were executed using the open source solver CAELUS. Effectiveness of each model was established using experimental measurements along with LES and DNS solutions available in the literature. Additionally, DES, DDES, and IDDES simulations were executed to show consistency with current hybrid models. It was shown that the dynamic hybrid turbulence models demonstrated a consistency the existing hybrid models in the fine grid limit as well as an increase in model effectiveness as the grid was coarsened.