Detachment of Buoyant Surface Jets Discharged on Slope

Abstract

Characteristics of a buoyant surface jet discharged on a sloping bottom are reviewed and a numerical experiment is performed to evaluate the depth at the point where the jet detaches from the bottom. This calculation is important in the context of predicting dilution and spreading characteristics of buoyant discharges, for example, associated with heated discharges from power plants. The experiment is based on a direct numerical solution of the longitudinally integrated momentum equation, which takes into account entrainment and bottom friction. Results are compared with laboratory and field data reported in the literature, as well as previous empirical relations for calculating this depth. It is found that the appropriately scaled detachment depth varies with the inverse of the discharge densimetric Froude number. The scaled depth decreases with increases in either the entrainment or bottom friction coefficient, but increases with increasing slope. A minor effect of discharge aspect ratio is also shown. An equation is developed for predicting detachment depth and the results help to resolve differences seen in previous relations.