A new very large eddy simulation model for simulation of turbulent flow

Among various hybrid RANS/LES methodologies, Speziale's Very Large Eddy Simulation (VLES) is one that was early proposed and is a unified simulation approach that can change seamlessly from RANS to DNS depending on the numerical resolution. The present study proposes a new improved variant of the original VLES model. The advantages are achieved in two ways: (1) RANS simulation can be recovered near the wall which is similar to the Detached Eddy Simulation (DES) concept; (2) An LES subgrid scale model can be reached by the introduction of a third length scale, i.e. integral turbulence length scale. Thus the new model can provide a proper LES mode between the RANS and DNS limits. This new methodology is implemented in the standard $k-\epsilon$ model and Wilcox's $k-\omega$ model. Applications are conducted for the turbulent channel flow at $Re_{\tau}=395$ and turbulent flow past a square cylinder at $Re=22000$. Results are compared with previous studies. It is demonstrated that the new method is quite effective in resolving the large flow structures, and can give satisfactory predictions on a very coarse mesh