Analysis of turbulence suppression in sediment-laden saline currents

SHRINGARPURE, MRUGESH; CANTERO, MARIANO I.; BALACHANDAR, S.

Procedia Engineering

Elsevier

Año: 2015 vol. 126 p. 16 - 23

The present work extends the results of Cantero et al.[1] and Shringarpure et al.[2] to the cases of sediment-laden saline currents.The flow is modeled as a channel flow where the forcing is exerted by salinity and suspended sediments. The resulting set ofequations are solved by direct numerical simulation (DNS) for shear Reynolds number Re τ = 180. The DNS results show that byincreasing the forcing due salinity, the flow can be held in a turbulent state whereby large sediment particles can be maintained insuspension. Typically, such large sediment particles would not be able to sustain the flow by themselves. The DNS results alsoshow that for large sediment loads there is a transition to total turbulence suppression. This transition is abrupt and is caused bysmall changes in the sediment load. Here, salinity can be interpreted as a fraction of sediments that are fine enough that theirsettling velocity is negligible. Thus, the case of sediment-laden saline currents is physically equivalent to a simplified bi-dispersemodel where the fine sediments do not settle. Finally, this work shows that the original results by Cantero et al.[1] and Shringarpureet al.[2] hold when they are reinterpreted under the light on an effective settling velocity.