Sediment transport in steady turbulent boundary layers: Potentials, limitations, and perspectives for Lagrangian tracking in DNS and LES

In this paper, we discuss the applicability of the Eulerian-Lagrangian point-particle approach to predict sedimentation and resuspension phenomena in solid-liquid flows. We start from results obtained for dilute systems and we examine to which degree such results can be applied to sedimentation phenomena, in which higher concentration values will be at some point relevant. We examine critical issues in state-of-the-art direct and large-eddy simulations of sediment dynamics in turbulence, starting from concepts and ideas that were derived from a systematic study of particle transport in turbulent boundary layer and applied to several canonical flow configurations (closed/open channel with flat/wavy bottom). We focus on issues related to high sediment concentration near the boundary and we examine critically results from original modelling strategies specifically aimed at dealing with boundary conditions where concentration peaks, with inter-particle collisions and with subgrid scale models in higher Reynolds number simulations employing LES.