Sand erosion with a traversing circular jet

Trailing suction hopper dredgers (TSHDs) are the workhorses of the dredging industry. These ships trail a draghead over the seabed to excavate soil. It is now common for TSHDs to be equipped with water-jet assisted dragheads to enhance their production. These jets are vital for efficient dredging and are used to fluidise the soil. This reduces forces on the cutting teeth and makes the sand–water mixture more suitable for upward transport through the suction pipe. This research focuses on understanding the interaction of a horizontally moving, vertical jet with a (non-cohesive) sand bed. The aim is to predict the jet production, which is the mass flux of fluidised sand. Experiments have been executed at the Dredging Laboratory of the Delft University of Technology. The results were compared to an existing jet production formula. The formula states that the mass flux of fluidised soil is linearly dependent on the jet momentum flux. It is a simple and practical formula; however, it has not been validated thoroughly. More investigation was therefore needed. On average, the formula was shown to be in fairly good agreement with the experiments.