Article,
Discrete Element Method simulations of the saturation of aeolian sand transport
GEOPHYSICAL RESEARCH LETTERS, 42 (6): 2063-2070 (2015)
DOI: 10.1002/2014GL062945
Abstract
The saturation length of aeolian sand transport (L-s), characterizing
the distance needed by wind-blown sand to adapt to changes in the wind
shear, is essential for accurate modeling of the morphodynamics of
Earth's sandy landscapes and for explaining the formation and shape of
sand dunes. In the last decade, it has become a widely accepted
hypothesis that L-s is proportional to the characteristic distance
needed by transported particles to reach the wind speed (the drag
length). Here we challenge this hypothesis. From extensive numerical
Discrete Element Method simulations, we find that, for medium and strong
winds, Ls<mml:msubsup>Vs2</mml:msubsup>/g, where V-s is the saturated
value of the average speed of sand particles traveling above the surface
and g is the gravitational constant. We show that this proportionality
is consistent with a recent analytical model, in which the drag length
is just one of four similarly important length scales relevant for sand
transport saturation.
