Investigation of Embedded Wall-Modeled LES for the Prediction of Smooth-Body Separation in a Diffuser

Abstract

Embedded Wall-Modeled LES is investigated and validated through the unsteady flow simulation of a simple diffuser flow. The near-wall turbulence in the embedded LES region is modeled by the Improved Delayed Detached Eddy Simulation, while the development of a turbulent boundary layer inside that region is aided by the Synthetic Turbulence Generator. The subjects of investigation include the flow averaging time delay for hybrid simulations based on preliminary RANS calculations, the grid sensitivity of solutions derived through the use of synthetic turbulence and the dampening of turbulent vortices towards the outflow boundary by grid stretching. During these investigations, the possibility of hybrid simulations on coarser grids through the use of local grid refinement around the synthetic turbulence injection position is analyzed.