Structures in Oscillating Boundary Layer Flows

Spanwise wall oscillations in turbulent shear flows can lead to a substantial reduction in skin friction, owing to the apparent disruption of near-wall vortices. However, it is as-yet unclear exactly how wall oscillations affect nonlinear flow structures in these flows, particularly in open boundary layers. This presentation will discuss flow structures responsible for the transition to turbulence in a variety of oscillating boundary layer problems, including the Stokes boundary layer (pure oscillation) and oscillations on sheared boundary layers. It will demonstrate how oscillation affects the physics of the near-wall self sustaining process, creating a new variety of turbulent dynamics.