Study of Aerodynamic Grain Entrainment in Aeolian Transport

Aeolian transport controls landform formations on Earth and other planets and crucially affects the atmospheric system. With elaborate wind tunnel measurements, we find that the aerodynamic entrainment rate follows a yet unreported exponential increase in the intermittent regime and only complies with the expected linear law for the condition of continuous entrainment. Subsequently, we propose a model accounting for the effects of turbulence on aerodynamic entrainment based on the distribution of local shear stress to describe the experimental results. We also provide evidence that aerodynamic entrainment can be an efficient way to directly induce a horizontal grain transport comparable to the steady and saturated saltation in unsaturated conditions and should not be ignored. Our findings substantially modify the present interpretation of surface erosion and bear thus important consequences on future soil protection techniques.