3D simulations of dredged sediment disposal plumes over a realistic bathymetry using a two-phase model

The vertical propagation of a dredged spoil release and the propagation of the gravity current due to the sediment cloud collapse at the bottom is investigated in the present study. A two-phase numerical model, able to calculate the amount of the detrained material as function of the conditions under which it is disposed, is developed in Fluent. Initially, a 2D case was validated versus experimental and numerical data available in literature. The validation includes the falling time of the sediment cloud, the of the evolution of the cloud bottom as well as the time evolution of the current front. Further, a 3D two-phase model is presented that simulates the complete process of sediment release over a realistic bathymetry and during realistic flow conditions. The outcome of the 3D model shows how the material is distributed on the river bed, during and immediately after the release of sediment by a hopper dredger.