Scaling laws in aeolian sand transport
Résumé
Via wind tunnel experiments on aeolian sand transport, we provide evidences that over an erodible bed the grainvelocity in the saltation layer and the saltation length are almost invariant with the wind strength, whereas over anon-erodible bed these quantities vary significantly with the air friction speed. It results that the particle transportrate over an erodible bed does not exhibit a cubic dependence with the air friction speed, as predicted by Bagnold,but a quadratic one. This contrasts with saltation over a non-erodible bed where the cubic Bagnold scaling holds.Our findings emphasize the crucial role of the boundary conditions at the bed and may have important practicalconsequences for aeolian sand transport in natural environment