Краткое описание

The massively separated unsteady flows are numerically simulated by DDES based on k-ω-SST model. The original dissipation is multiplied by a function, which is less and equal to 1, to effectively reduce the effect of numerical dissipation in the recirculation region. A very important parameter in DDES, C_DES, is recalibrated using decaying of isotropic turbulence. Two cases are simulated, where one is NACA0021 at incidence of 60 degrees and another is tandem-cylinders. In the first case, the effect of spanwise length is investigated and longer spanwise length can obtain better results; in the second case, the fully turbulent and quasi-laminar assumptions are both applied to predict the flow. The quasi-laminar assumption performs like the trip in the experiment and it can improve the results, such as velocity, TKE, and so on, in a certain extent.