Circulation and trajectories of vortex rings formed from tube and orifice openings

A model for vortex ring circulation developed by the author [P.S. Krueger, An over-pressure correction to the slug model for vortex ring circulation, J. Fluid Mech. 545 (2005) 427–443] is discussed. Numerical simulations of vortex ring formation are used to provide model closure and validation data for orifice-type generators. The model results agree well with the simulation results for both tube and orifice configurations provided the jet duration is sufficiently long. For short jets, the model discrepancy is explained in terms of an interaction between the primary and stopping vortices.