Numerical simulation of turbulent sediment transport
Durán, O.; Andreotti, B.; Claudin, P. (2013). Numerical simulation of turbulent sediment transport, in: Van Lancker, V. et al. (Ed.) MARID 2013: Fourth International Conference on Marine and River Dune Dynamics. Bruges, Belgium, 15-17 April 2013. VLIZ Special Publication, 65: pp. 97-105 In: Van Lancker, V.; Garlan, T. (Ed.) (2013). MARID 2013: Fourth International Conference on Marine and River Dune Dynamics. Bruges, Belgium, 15-17 April 2013. VLIZ Special Publication, 65. Royal Belgian Institute of Natural Sciences/SHOM/Flanders Marine Institute (VLIZ): Oostende. ISBN 978-2-11-128352-7. 338 pp., more In: VLIZ Special Publication. Vlaams Instituut voor de Zee (VLIZ): Oostende. ISSN 1377-0950, more |  |
| Authors | | Top | - Durán, O.
- Andreotti, B.
- Claudin, P.
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| Abstract | Sediment transport is studied by means of two phase numerical Simulations based on a discrete element method for particles coupled to a continuum Reynolds averaged description of hydrodynamics.. We analyse the mechanisms at the grain scale in the case of bed load, in order to give support to empirical transport laws. The vertical velocities of the grains are small and sediment transport occurs in a thin layer at the surface of the static bed. Steady, or `saturated' transport is reached when the fluid borne shear stress at the interface between the mobile grains and the static grains is reduced to its threshold value. The number of grains transported per unit surface is therefore limited by the flux of horizontal momentum towards the surface. However, the fluid velocity in the transport layer remainsalmost undisturbed so that the mean grain velocity scales with the fluid shear velocity u* , eventually leading to a sediment flux scaling with the third power of u* . The influence of the grain to fluid density ratio is systematically studied to reveal the transition between sub-aqueous bedload and aeolian saltation, for which the transport law has a different scaling with u* . Based on the mechanisms identified in the steady case, we discuss the transient of saturation of sediment transport and in particular the saturation time and length. Finally, we nvestigate the exchange of particles between the mobile and static phases and we determine the exchange time of particles. |
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