An Experimental Study of Rectangular Surface Jets

The flow field for rectangular surface jets in a wide and deep water environment was studied using Particle Imaging Velocimetry (PIV) and a Laser Induced Fluorescence (LIF) visualization technique. Laminar and turbulent regimes were considered. Results showed that the jet spread linearly in both vertical and lateral directions. The vertical spreading rate of the rectangular jet was similar to the spreading rate of a plane surface jet. Flow visualization revealed two distinct jet regions with significantly different lateral spreading rates. Only a thin layer close to the surface was spreading at a rate much greater than the vertical spreading rate. Below this thin surface layer the jet was spreading at a rate comparable to the vertical spreading rate. The development and spreading of the thin surface layer appeared to be linked to dynamic interactions of stream wise vortices with the free surface