Numerical Investigation of Turbidity Currents Flowing Through Minibasins on the Continental Slope

Abstract

Abstract Numerical investigation of the dynamics of turbidity currents flowing through a series of minibasins is conducted. A two-dimensional vertical-structure-resolving finite-volume model is developed to solve the Reynolds-averaged Navier-Stokes equations along with the sediment mass conservation equation in a non-orthogonal grid system. In addition, the Exner equation of bed sediment conservation is solved to study changes in the bed level. The model is verified against three laboratory experiments conducted by Lamb et al. (2004) and Lamb et al. (2006) to study the dynamics of continuous-feed turbidity currents and the depositional characteristics in a minibasin. Simulation results show that the sediment deposition pattern predicted by the model is in reasonably close agreement with the measurements. The model successfully captures draping of sediment over the initial bed irregularities. Vertical distributions of concentration profiles are also found to be in good agreement with the measured data. Field-scale investigation is carried out by considering two minibasins in a series. It is observed that the inflow condition of a continuous-feed turbidity current can strongly influence the bed morphology of the minibasin. For the same inflow velocity and suspended-sediment concentration, larger sediment particles in the inflow cause overall deposition while smaller sediment particles lead to erosion.