Extinction of near-bed turbulence due to self-stratification in turbidity currents: The dependence on shear Reynolds number
ABSTRACT: Turbidity currents are dense bottom flows driven by suspended sediment that occur in lakes and the ocean. Turbidity currents are self-stratifying in that the agent of the density difference, i.e., sediment, must be maintained in suspension if the flow is to be sustained. It has recently been shown using Direct Numerical Simulation that under appropriate conditions, the upward normal profile of suspended sediment may show a gradient sufficient to cause the extinction of turbulence near the bed. This extinction creates conditions favorable to the emplacement of massive turbidites, i.e., sediment deposits which show no evidence of reworking by the flow. The results were established using a shear Reynolds number of 180. Here the question of Reynolds invariance is studied by repeating the calculations with a shear Reynolds number of 400.