Discrete Element Simulation on Sand-Bed Collision Considering Surface Moisture Content

Abstract

The process of aeolian sand transport is an important mechanism leading to the formation and evolution of local landforms in coastal areas and desert lakes. For a long time, the role of surface moisture in incipient motion of sand grains by wind stress has been extensively studied but, in fact, sand-bed collision is the main mechanism in steady aeolian sand flow. At present, the lack of understanding of surface moisture content on sand-bed collision limits the application of aeolian sand transport models in wet coastal areas. In this paper, we adopt numerical simulations to discuss and analyze the effect of cohesive forces formed by surface moisture content on the sand-bed collision process based on discrete element method. High density contact forces appear with the surface moisture increasing, and form a closed structure around the edge of crater to resist the avulsion in horizontal direction. Under high moisture condition, even though the ejected sand grains saltate away from the surface, the tension forces will prevent from leaving. The ejected number trend with incident velocity shows some nonlinear characteristics due to the unequally distributed force chains and liquid bridges in the unsaturated sand bed surface.

Effects of Covering Layer of Sand Particles on Particle‐Bed Collision and Aeolian Sand Transport

“…Aeolian sand transport models based on these four processes have been widely used in computer simulations of two‐phase aeolian‐sand flows on the surface of Earth, Mars, and other terrestrial planets (Carneiro et al., 2011, 2013; Durán et al., 2011, 2012; Fenton et al., 2003; Huang et al., 2010; Ji et al., 2014; Li et al., 2014; Shao, 2008; Zheng, 2009). However, compared with the literature on the movement of sand particles in the air, only a few studies provide a deep understanding of the collision process between sand particles and bed surfaces owing to the variations in the physical and mechanical properties of sand particles and the interaction between multiple sand particles (Dun et al., 2022; Kok et al., 2012); this restricts the improvement of the accuracy of aeolian sand transport simulation of terrestrial planets.…”

“…of the collision process between sand particles and bed surfaces owing to the variations in the physical and mechanical properties of sand particles and the interaction between multiple sand particles (Dun et al, 2022;Kok et al, 2012); this restricts the improvement of the accuracy of aeolian sand transport simulation of terrestrial planets.…”