Large eddy simulation of sediment transport in open-channel flow

Abstract

Large Eddy Simulation (LES) is used to investigate the 3D-transport of sediment suspension in an open channel flow at a Reynolds number based on the frictional velocity.An Eulerian model was employed to represent the fluid and the sediment phases. The subgrid-scale fluid stresses were modeled with the Smagorinsky model, whereas subgrid-scale sediment fluxes were based on a gradient approach. To avoid tuning constants, a dynamic procedure was applied. A two-way coupling between sediment and fluid improved the computational description of sediment transport. Sediment concentration profiles and the statistics of sediment fluxes are presented and compared with the Rouse profile and the RANS solution. The results obtained agree well with the theory and with measurements. The LES results also indicate that the assumption of a constant Schmidt number, as is mostly assumed in RANS simulations is erroneous.