Vortex generation at sharp edges: Two and three-dimensional effects

Vortices were generated at straight edges by an impulsively-started flow of water to determine steady and unsteady global aspects of the flow as the edge-angle was varied from 0 to 180 deg; trajectories of the vortex centers in the mid-plane during vortex generation for edge-angles 0 to 145 deg; and vorticity distributions and circulations at the nozzle in the mid-plane for edge-angles 0, 90 and 180 deg. The temporal development of the flow shows 3 phases; an initial phase, in which no vortex generates, the flow remaining attached despite the sharpness of the edge; a vortex-generating phase; and a final phase, which remains steady for a Reynolds number 3000 for nozzle-type flows and Re 10,000 for diffusor-type flows.