It is known that vortex rings formed by large stroke ratios (in a piston/cylinder arrangement) pinch off from their generating jets at a fairly constant universal time scale. In this paper we show that the hypothesis that at the pinch off the translational velocity of the ring equals the jet flow velocity near the ring is equivalent to the recently proposed idea based on a variational principle by Kelvin and Benjamin that the pinch off occurs when the apparatus is no longer able to deliver energy at a rate required for steady vortex ring existence. A formula for the propagation velocity of a thick vortex ring is also proposed and compared with available experimental data and empirical relations.
Skip Nav Destination
Research Article| March 01 2000
Energy and velocity of a forming vortex ring
Michael Shusser, Morteza Gharib; Energy and velocity of a forming vortex ring. Physics of Fluids 1 March 2000; 12 (3): 618–621. https://doi.org/10.1063/1.870268
Download citation file: