Management of Two-dimensional Channel Flow with a Pair of Streamwise Vortices (Behaviour of Streamwise Vortices and Mean Velocity Field)

Abstract

An experimental study has been made on the management of a two-dimensional turbulent channel flow with a pair of streamwise vortices. A common-flow down type streamwise vortex pair, which was generated by a pair of half-delta wings mounted on the wall, was introduced into the fully developed turbulent channel flow. The half-delta wings were as high as inner layer thickness of the channel flow. The mean velocity and Reynolds shear stress distributions were measured and some properties were obtained to find meanings of the vortex generator for management of turbulent channel flow. Convective motion of the secondary current is responsible for most of the streamwise momentum transfer toward the wall in the interaction between the vortices and the shear layer. In the velocity profile averaged over spanwise extent, velocity is accelerated below the vortex center and decelerated above the vortex center. Deformation of the mean velocity profile is remained over remarkable long downstream distance of 250 times wing height which corresponds to 50 times channel half-width H.