A numerical study on flow velocities, bed morphology and suspended sediment transport due to barge motion in a navigation channel

Abstract

Sediment suspension and motion due to vessel traffic in navigation channels is a challenging problem in the design and management of waterways, ports and navigation channels. This study utilised computational fluid dynamics (CFD) simulations to investigate the impact of vessel motion on bed morphology and sediment suspension. The work was carried out for a navigation channel with sloped banks, subject to motion-induced currents and waves generated by a rectangular barge with a blunt bow, towed at constant speed. A fine sand channel bottom was modelled. The simulations, consisting of six different scenarios with two bank slope angles, two tow speeds and two vessel widths, have been carried out by FLOW-3D Hydro software. It was found out that the most significant parameter affecting sediment motion is the tow speed of the vessel, which is coupled with the vessels squat. The study further shows that ship width also plays a critical role in predicting the risk of sediment accumulation in harbour and navigation channel projects, as an increase of only 15 % in vessel width results in a large increase of 72 % in the total amount of suspended sediment. An increase in bank slopes, on the other hand, is found to have a smaller effect (15 %) on the total suspended sediment concentration.