Relaxation processes in Aeolian transport
1 Institut de Physique de Rennes, UMR UR1-CNRS 6251, Université de Rennes 1, 35042, Rennes cedex, France
2 Laboratoire de Thermocinétique, Polytech. Nantes, CNRS UMR 6607, 44306 Nantes, France
3 GCGM, INSA de Rennes, Campus Beaulieu, 35043 Rennes, France
4 Laboratoire de Mécanique de Précision Appliquée, Université Ferhat Abbas Sétif 1, Algeria
Published online: 30 June 2017
We investigate experimentally the relaxation process toward the equilibrium regime of saltation transport in the context of spatial inhomogeneous conditions. The relaxation length associated to this process is an important length in aeolian transport. This length stands for the distance needed for the particle flux to adapt to a change in flow conditions or in the boundary conditions at the bed. Predicting the value of this length under given conditions of transport remains an open and important issue. We conducted wind tunnel experiments to document the influence of the upstream particle flux and wind speed on the relaxation process toward the saturated transport state. In the absence of upstream particle flux, data show that the relaxation length is independent of the wind strength (except close to the threshold of transport). In contrast, in the case of a finite upstream flux, the relaxation length exhibits a clear increase with increasing air flow velocity. Moreover, in the latter the relaxation is clearly non-monotonic and presents an overshoot.
© The Authors, published by EDP Sciences, 2017
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