Author(s): C. Braun; M. Garcia-Villalba; M. Uhlmann
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Keywords: No Keywords
Abstract: The hydrodynamic forces acting on the particles that form a rough bed are studied via direct numerical simulation of a turbulent open channel flow. The roughness elements have a spherical shape and are distributed in a single layer with cubical packing. The Reynolds number based on the bulk velocity, Ub, and the effective water depth, h eff, is Reb=3750. The particle Reynolds number based on the sediment diameter, D, and the friction velocity is D+= 79. The particle forces are analysed systematically by a statistical approach and compared to experimental results from the literature. Although different flow conditions were used in the experiments and the simulations, similar features for the mean force generating mechanism are obtained when scaled with the particle diameter and the bulk velocity. This indicates that significant features of the average force generating mechanism are persistent over a wide range of flow parameters, despite the remaining uncertainties related to the onset of sediment transport.
Year: 2009