DNS of Turbulent Boundary Layer with Time-Periodic Blowing through a Spanwise Slot

Abstract

Direct numerical simulations are extended to see the effects of time-periodic blowing frequency from a spanwise slot on a turbulent boundary layer. The time-periodic blowing frequency is given in a range 0≤f+≤0.08 at a fixed blowing amplitude of A+=0.5. The effects of the blowing frequency are scrutinized by examining the phase- or time-averaged turbulent statistics. A most effective blowing frequency is obtained at f+=0.03, where the maximum increases of Reynolds shear stress, streamwise vorticity fluctuations and energy redistribution are made. The phase-averaged stretching and tilting terms are studied for analyzing the increase of streamwise vorticity fluctuations which is closely related to turbulent coherent structures.