Some important physical phenomena in flows with separated turbulent boundary layers

An investigation is conducted concerning the case of a steady freestream, incompressible, two-dimensional mean flow over a streamlined or gently curved body or surface with a developed turbulent boundary layer upstream of the separation zone. Thus, in essence, the separation of the boundary layer is due to an adverse pressure gradient. Experimental chordwise distributions of the suction side velocity just outside the boundary layer for an airfoil at several angles of attack are presented in a graph. It is concluded that in the separated flow zone the velocity and pressure just outside the shear layer approach the free-streamline condition of constant pressure and velocity. In the case of trailing edge separation, there is apparent strong interaction between the wakes of the suction and pressure sides, since the thickness and velocity distribution in the considered region is controlled by both shear layers. A description is given of the attached boundary layer characteristics, the separated shear flow, and the wake flow.