Comparisons of Three Improved DES Methods on Unsteady Flows Past Tandem Cylinders

Three advanced DES-type models coupled with adaptive dissipation scheme, DDES-2003/2006 and IDDES, are applied to predict the unsteady flow past tandem cylinders. The main differences among them are the shield functions and length scales, which leads to significant differences in mean turbulence kinetic energy, root mean square of pressure, instantaneous vorticity, and so on. The computational results are compared with almost all available measurements. These three models show good capability for the massive separation flows. IDDES performs relatively better than other two SST-DDES models. Furthermore, IDDES matches well with the measurements with trips on the rear cylinder surface.