Flow Visualization in Complex Turbulent Flows

Angled injection of submerged laminar plane jets into a turbulent boundary layer developed along a vertical wall of a large recirculating water channel was visualized. The mixing layers associated with the jet and their interaction with the boundary layer and resulting transition mechanisms in the generation of turbulence are described. A recirculation bubble region related to separation is revealed, and primary systematic transverse vortex structures formed in the outer mixing layer of the jet are characterized. A physical model is proposed which describes the initiation, the formation, and the coalescence of vortices as part of a transition process in the development of turbulence.