VLES turbulence modelling for separated flow simulation with OpenFOAM

In the present study, a detailed assessment investigation of Very-Large Eddy Simulation (VLES) method is performed using the open-source toolbox OpenFOAM for the simulation of turbulent separated flow. The VLES method is a unified simulation approach enabling a seamless evolution from Reynolds-Averaged Navier-Stokes (RANS) to quasi Direct Numerical Simulation (quasi-DNS) depending on the numerical resolution. Two VLES models, i.e. VLES-k-ε and VLES-k-ω, are implemented in OpenFOAM and applied in the present study. In order to assess the performance of VLES models based on the framework of OpenFOAM, four classic separated flow are selected and investigated in details, including the flow past a triangular bluff body at Re ​= ​45,000, the flow past a backward facing step at Re ​= ​40,000, the periodic hill flow at Re ​= ​10,595, and the flow past a circular cylinder at Re ​= ​41,300. The comparisons between VLES simulation results and experiments give an indication on the adequacy and accuracy of the VLES modelling method based on the OpenFOAM toolbox. The VLES-k-ω model performs slightly better than the VLES-k-ε model on a relatively low mesh resolution, especially in predicting the turbulent separation flow induced by the pressure gradient on a smooth surface. The results also demonstrate the reliability and accuracy of the VLES modelling based on OpenFOAM platform for complex separated flow simulations.