The initial development of a submerged laminar round jet

Abstract

Experimental results are presented for the speed of travel of the spherical vortex at the front of a suddenly switched on, submerged, laminar jet in the Reynolds number range 80 < Re < 500. The results show that the speed of advance of the front is approximately one half of the speed of a fluid element on the axis of the steady jet. The experimental data are well correlated by an approximate model of the jet–vortex interaction in which the vortex is treated as a liquid drop with averaged properties. An auxiliary result is a new correlation for the axial variation of the velocity of a steady jet.