Modeling density currents with hydrostatic and non-hydrostatic solvers

Abstract:

Density currents are subaqueous analogs of rivers. They have an important role in shaping bottoms of freshwater lakes and can create leveed channels extending several kilometers on submarine fans whenever the density difference is caused by suspended sediments. Density currents are usually modeled using non-hydrostatic solvers. However, it is possible to demonstrate that both hydrostatic and non-hydrostatic solvers can correctly model velocity and density profiles. In order to do so, we employ the numerical model called Delft3D. The major difference between the two modeling approaches relies on the correct description of the interface between the density current and the ambient water. The hydrostatic solver cannot reproduce the Kelvin-Helmotz instabilities that are generated. On the contrary, the non-hydrostatic solver manages to both reproduce vertical profiles and instabilities at the interface.