Brief communication A revised slug model boundary layer correction for starting jet vorticity flux

The flux of vorticity from a piston-cylinder vortex generator is commonly approximated using a model in which the fluid efflux is treated as a uniform slug of fluid with negligible boundary layer thickness. Shusser et al. (2002) introduced a correction to the slug model that accounts for boundary layer growth within the cylinder. We show that their implemented boundary layer solution contains an error, leading to an underestimate of the calculated boundary layer growth. We present a corrected model that agrees more closely with experimental measurements of starting jet vorticity flux and vortex ring core thickness.