Anomalous scaling of aeolian sand transport reveals coupling to bed rheology

Abstract

Authors: Thomas Pähtz, Katharina Tholen, Sandesh Kamath, Eric Parteli, Klaus KroyTitle: Anomalous scaling of aeolian sand transport reveals coupling to bed rheologyPredicting transport rates of windblown sand is a central problem in aeolian research, with implications for climate, environmental, and planetary sciences. Though studied since the 1930s, the underlying many-body dynamics is still incompletely understood, as underscored by the recent empirical discovery of an unexpected third-root scaling in the particle-fluid density ratio [1]. Here, by means of grain-scale simulations and analytical modeling, we elucidate how a complex coupling between grain-bed collisions and granular creep within the sand bed yields a dilatancy-enhanced bed erodibility. Our minimal saltation model robustly predicts both the observed scaling and a new undersaturated steady transport state that we confirm by simulations for rarefied atmospheres [2].[1] Pähtz, Durán, Scaling laws for planetary sediment transport from DEM-RANS numerical simulations, https://arxiv.org/abs/2203.00562[2] Tholen, Pähtz, Kamath, Parteli, Kroy, Anomalous scaling of aeolian sand transport reveals coupling to bed rheology , Physical Review Letters, accepted.