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Sand transport over a barchan dune.

Charru, François and Laval, Vincent Sand transport over a barchan dune. (2013) In: 4th Conference on Marine and River Dune Dynamics (MARID IV), 15 April 2013 - 17 April 2013 (Bruges, Belgium).

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The present work investigates an important and yet unsolved issue: the relationship between the sand flux and the fluid shear stress over a spatially varying bed of particles. It is now recognized that over such a bed, the particle flux is not in equilibrium with the shear stress: there is some lag related to the particle inertia or particle settling. A confident modelling of this relaxation phenomena and the corresponding length scales, is still lacking (Charru, Andreotti and Claudin 2013). This question is investigated here from experiments on barchan dunes in a closed-conduit water flow. From visualizations with a high-speed camera and a tracking algorithm, the particle motion over the whole dune surface is determined: particle trajectories, local velocity and surface density of the moving particles, and local particle flux. The relationship between the local particle flux and local shear stress (estimated from previous analyses) is investigated. Surprisingly, the particle flux appears to be out-ofequilibrium over the whole dune surface, with saturation length much larger than expected.

Item Type:Conference or Workshop Item (Paper)
HAL Id:hal-03670432
Audience (conference):International conference proceedings
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Laboratory name:
Deposited On:18 Dec 2013 10:12

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