research: Vortex Sheets

 

Generation of a vortex dipole

 

These experiments examines the flow field in the region where a moving wall slides under a stationary one. This produces an interesting flow phenomena with relatively simple generation geometry. The data reveals that in the absence of an apparatus length scale, a vortical structure forms a the junction and appears to scale in a self-similar fashion. The transitional regime of vortex development is marked by the appearance of an instability on the perimeter of the vortical structure. The instability mechanism appears to be centrifugal in nature.

The following movies are of a vortex with the top half of the ring moving right to left:

 

• cross-section movie
• streamwise instability movie
• vorticity movie

Reference: Instability of a junction vortex - J. J. Allen and T. Naitoh Submitted for review to the Journal of Fluid Mechanics (2002) [download PDF]