Three-dimensional modeling of density current. II. Flow in sinuous confined and uncontined channels

Abstract

The evolution of a density current in meandering subaqueous channel is studied using a three-dimensional numerical model. The objective of the study is to gain insight into the effect of curvature on the structure of a density-driven flow. The model is applied to three different cases: confined flow in a curved and in a sinuous channel, and uncontined flow in a sinuous channel. Similar to open channel flow, the primary flow structure is only nominally affected by channel curvature. At the apex of a channel bend, different layers of the density current display a varied but considerable degree of superelevation. In the confined flow cases, a strong circulation cell forms near the channel bottom and additional weaker cells develop near the top of the current. The strength of the bottom dominant cell is found to be similar to that of the single circulation cell observed in the subaerial environment. Significant flow stripping occurs towards the outside overbank area in the uncontined case. Due to the dominant effect of stripping, the secondary flow becomes muted and only one circulation cell develops near the channel bottom in this case. The size and strength of this cell is relatively small.