Simulation of bed load transport in turbulent open channel flow

The paper reports on direct numerical simulations of a particle-laden open channel flow carried out to investigate the interaction between the dispersed and the continuous phase. The dispersed phase is represented by an immersed boundary method. The particle-particle collisions are accounted for by a physically motivated collision model. Two cases, one with shear stress below the threshold of mobilization and the other with shear stress above the threshold are considered. The different density ratios lead to different types of modification of the flow field by the formation of density-specific patterns of the particles. Light particles do not attain resting states but saltate evenly distributed in span-wise direction. Heavy particles tend to form stream-wise clusters of inactive particles. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)