Interaction between boundary layer and wakes of different bodies

Measurements of mean velocity and Reynolds stresses have been made when the wakes of a streamlined body and a bluff body interact with the boundary layer on a flat wall. The streamlined body is the NACA 0012 airfoil, and the bluff body is a rectangular cylinder. The two bodies have the same drag and are placed such that at the initial station behind the wake-producing body, the lower edge of the wake in the two cases is at the same height above the bottom wall. It is found that though at the initial station the bluff-body wake is narrower and shallower than the airfoil wake, the level of turbulent fluctuations is higher in it, which causes faster mixing, and the velocity profile becomes monotonic earlier in the bluff-body case. Thus, for the same drag, the mixing is faster with a bluff body than with a streamlined body. © 1990 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.