Experimental modeling of gravity underflow in a sinuous submerged channel

Abstract

This paper describes the results of an experimental study involving density driven gravity underflow in a submarine sinuous channel. A single bend channel with sine generated planform was constructed inside a laboratory basin. Saline density flow was released at a constant rate at the upstream end of the channel which was submerged under fresh water. Instantaneous velocity data recorded within the body of the developed current were used to derive the vertical structures of the streamwise and cross‐stream velocity. The vertical distributions of the streamwise and lateral velocity were found to vary modestly between cross sections and also within an individual cross section. The distance of the maximum velocity position from the bed was found to vary between 0.4 and 0.6 times the local current thickness. In the vicinity of the bend apex the curvature effect led to the development of two helical flow cells with one forming on top of the other. The sense of rotation of the bottom cell was similar to that observed in curved open channel flow, while the upper circulation cell had an opposite sense of rotation. Turbulent kinetic energy profiles were derived from the instantaneous velocity data. The observed turbulent kinetic energy profiles confirm some previous observations that the location of the maximum velocity in a density underflow also corresponds to significant reduction in turbulent kinetic energy.