On the formation of the chain of ring-like vortices in a transitional boundary layer

One mechanism by which laminar flow becomes turbulence is through the insta bility of vortex interaction. The nonlinear evolution of the interactions b etween the h-vortex and the secondary closed vortex has been investigated. This nonlinear instability process leads to some fundamental changes in the topology of flows. Experimental observations are presented here showing th e formation of a chain of ring-like vortices, which generate high-frequency spikes on time traces in a transitional boundary layer.