Evaluation of XY-SAS model for separated flows

Xu-Yan-scale adaptive simulation (XY-SAS) is a new one-equation scale-adaptive simulation model proposed on the basis of average vorticity. It resolves the Reynolds average navier-stokes(RANS)-large eddy simulation(LES) interface problem in detached eddy simulation (DES) with much smaller computation cost compared with pioneer SAS model. It was analyzed that XY-SAS model can provide proper damping of resolved turbulence at high wave number end of the spectrum compared with pioneer one. The limiter was removed based on mechanics analysis and this model was improved. Flat plate boundary layer and square cylinder were chosen as test cases for further evaluation of XY-SAS. The numerical results agree well with the experimental data, which proves that XY-SAS is an effective method for large scale separation flow and the model itself is complete. The model viscosity is determined adaptively according to the local flow behavior. A smooth transition is achieved from RANS to LES region.