Vertical structure of continuous release saline and turbidity currents

Abstract

This paper reports new experimental results on the mean velocity, excess fractional density, and turbulence structures of conservative and particulate density currents. Experiments were conducted in a laboratory flume consisting of a ramp followed by a horizontal bed. Instantaneous point velocity along the body of a continuous, developed underflow was measured using two 16 MHz Acoustic Doppler Velocity Probes (ADV). Mean velocity, turbulent kinetic energy (TKE) and Reynolds stress components have been derived from the instantaneous velocity data. The normalized mean velocity, Reynolds stress, and TKE profiles have been derived and plotted in different groups corresponding to saline and particulate gravity currents over sloping and horizontal beds. The Reynolds‐averaged velocity shows excellent similarity collapse in these plots, while the Reynolds stress and the TKE profiles display good similarity in the wall‐bounded shear flow region. Vertical profiles of the TKE display two peaks separated by a zone of low turbulence around the position of the maximum velocity. The ratio of the maximum to the layer‐averaged TKE is found to be approximately 1.5. The TKE at the low turbulence zone between the peaks is approximately 50% of the depth‐averaged value.