Anomalous Scaling of Aeolian Sand Transport Reveals Coupling to Bed Rheology

Predicting 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. 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.

Automated summary

Predicting the transport rates of windblown sand is important for various scientific fields and has been studied since the 1930s. However, the underlying dynamics of many-body interactions are not yet fully understood. In this study, we use simulations and modeling to show that the coupling between grain-bed collisions and granular creep within the sand bed enhances bed erodibility. Our minimal saltation model accurately predicts the observed scaling and a new undersaturated steady transport state.