Assessment of Local Blowing and Suction in a Turbulent Boundary Layer

Abstract

Effects of local blowing or suction from a spanwise slot on a turbulent boundary layer flow are investigated using the direct numerical simulation technique. Three different blowing or suction velocities are imposed on the slot keeping blowing or suction flow rate constant. The recoveries of mean wall pressure for the different blowing velocities collapse well on the same recovery line. However, each wall pressure recovers just after the slot for suction. In the blowing case, the relaxation of rms wall pressure fluctuations and pressure gradient after the slot is seen and the relaxation distance from the slot center is nearly constant for three different blowing velocities. In the suction case, the flow recovers from the immediate rear of the slot. These features are also observed in three-dimensional views of the near-wall vortices.