Applicability of LES to the turbulent wake of a rectangular cylinder—Comparison with PIV data

Abstract

The applicability of the large eddy simulation (LES) technique to wake flows past a bluff body should be clarified in order to improve numerical accuracy for the estimation of aerodynamic forces and pressures acting on a bluff body. Here, we conduct both LES and particle image velocimetry (PIV) measurement for turbulent flows past rectangular cylinders with a depth/breadth ratio ranging from D/B=2.00 to 3.00 at Re=2000 and 20,000, which sensitively change turbulence structures due to flow separation and reattachment. For LES, we use the dynamic Smagorinsky-type SGS (sub-grid scale) model. First, at Re=2000 where pure turbulent viscosity without numerical viscosity is realized, the accuracy of the SGS modeling for the prediction of not only aerodynamic characteristics but also turbulence statistics in the wake of rectangular cylinders is examined in comparison with PIV data. Furthermore, at Re=20,000 where the numerical dissipation must be incorporated, we clarify the unfavorable effects of the numerical dissipation on the turbulence structures in the wake.