LARGE EDDY SIMULATION OF SECONDARY FLOWS OVER LONGITUDINALLY-RIDGED WALLS

In this paper, large-eddy simulations of a turbulent channel flow with longitudinal, large-amplitude, ridges are carried out. This flow exhibits large secondary recirculations in the cross-stream plane that need to be properly simulated in order to evaluate with enough accuracy the spanwise distribution of the primary as well as the secondary wall stress. Available DNS data at low Reynolds number as well as data from an experimental investigation at a moderate Reynolds number are matched. Our LES results agree satisfactorily with the DNS data at Re τ = 140, and with the experimental data at Re τ = 580. This investigation shows that the intensity and topology of the secondary flow is dependent on the Reynolds number of the flow. Unlike previous investigations, the present results have also shown that when the Reynolds number is large enough near-wall, small and intense cellular flows appear, which may produce localized secondary wall stresses. The analysis of the coherent structures that evolve in the buff...