Simulation of Aerodynamic Entrainment Process of Soil Crust Based on Discrete Element Method

Wind erosion is one of the main causes of dust storms and land desertification in arid and semi-arid areas, and the existence of soil crust significantly increases resistance to wind erosion. However, the aerodynamic entrainment mechanism of crusted soil, a typical continuous-discrete coupled system, requires further investigation. In this study, the discrete sand particles and the continuous soil crust characterized by the spring damping model combined with the parallel bonding model were established in discrete element method (DEM). And the effects of crust thickness and strength on aerodynamic entrainment were studied. Simulation results showed that in comparison to the discrete sand, soil crust increased the threshold friction velocity to a factor of two to seven. The linear increase of particle take-off velocity and take-off angle with friction velocity was unaffected, and the thickness of the crust did not affect the distribution law of take-off velocity, or angle, but it did lower the take-off angle of the particles by about fifty percent. These results provided new insights into the mechanisms underlying the effects of crust on wind erosion.