Numerical Simulation of Turbidity Current in Approach Channels with a Closed End

Abstract

This study aims to gain insights into turbidity currents in approach channels with a closed end. A vertical two-dimensional numerical model was introduced, which considers the viscosity of sediment and assumes rheological behavior of the very near-bed layer. The dynamic propagation of the turbidity current, both before and after it reaches the closed end, was studied. It is found that before the turbidity current reaches the closed end, the velocity of the current head is unaffected by the length of the channel, while the velocity and height of the turbidity head are decreased along the channel. When the head reaches the wall, a surge and reverse flow occur. After a quasi-stable state has formed, results show that the speed of current along the channel decreases gradually to zero speed at the closed end. The current speed increases asymptotically with the initial sediment concentration toward a limiting value at high concentrations. The depth of the turbidity current is about 0.3–0.6 times the total depth. The sediment concentration is reasonably constant along the channel. The study deepens the understanding of turbidity currents in these special channels and provides theoretical guidance for engineering practice.