JET BEHAVIOUR IN SHALLOW RECEIVING WATER.

A brief description is given of research carried out using physical model facilities to examine some of the characteristics of turbulent jet entering shallow receiving water. Two outfall situations which are common in practice, the non-buoyant slot jet and the buoyant round jet, have been investigated. Hot-film anemometry in the first case, and a system of thermistors in the second, were used to quantify the various mixing processes. In both situations it is shown that the mixing characteristics (e. g. the jet centre-line location, the centre-line velocity, or the lateral spread rates) are, in many circumstances, significantly different from those of the free (deep-water) jet. The slot jet investigation illustrates that, in addition to jet entrainment, the physical effect of induced vortex action is important and is responsible, in part, for the particular jet behaviour in shallow receiving water conditions. These effects are also evident in the buoyant round jet.