Maximum Velocity Decay in a Submerged Laminar Jet Issuing from a ‘Long Tube

Abstract

Decay of the maximum velocity of an incompressible, axisymmetric, submerged, laminar free jel is related to the second derivative of the velocity profile at the centre line by using the momentum equation along the jet axis with boundary layer approximations. Using this decay relation and the experimental fact that the velocity profile near the jet axis remains parabolic it is shown that maximum velocity decay is linear in the developing region. The length of the developing region and the location of the virtual origin are obtained by matching the maximum velocity variations at the boundary between the developing and fully developed regions. These values are compared with the results of conventional jet matching schemes and with other information available in the literature.