Multiple Time Scales and Coupled Mathematical Modeling of Turbidity Currents

Turbidity currents can entrain sediment from the bottom boundary, resulting in active sediment transport and rapid bed deformation, which in turn affects the evolution of turbidity currents. Yet previous mathematical models of turbidity currents are mostly based on mild bed deformation and weak sediment transport, in which the feedback impacts of sediment transport and bed deformation have been ignored to a certain extent. It so far remains unknown if this could have considerable effects on the evolution of turbidity currents. This paper extends the recent analysis of multiple time scales of subaerial sediment-laden flows to subaqueous turbidity currents. The relative time scale of bed deformation is demonstrated to delimit the applicability region of layer-averaged models for turbidity currents. Self-accelerating turbidity currents are revisited to substantiate the significance of fully coupled modeling for turbidity currents featuring active sediment transport and rapid bed deformation.