Transport characteristics of aeolian sand near different thresholds

Abstract

The characteristics of wind-blown sand have mainly been derived from steady and continuous sediment transport studies. However, aeolian sand transport exhibits spatiotemporal variability near the threshold, with intermittent transport becoming prominent. This study employs three-dimensional numerical simulations to explore the transport characteristics of wind-blown sand near different thresholds. The results demonstrate varying transport capacities close to the rebound and impact entrainment thresholds, which are 0.38 and 0.7 times the fluid threshold respectively, driven by distinct entrainment mechanisms. Aerodynamic entrainment predominates near the rebound threshold, which shows that the ratio of aerodynamic entrainment particles to splash entrainment particles exceeds 100 with Shields number 0.003. However, splash entrainment becomes dominant when wind velocity surpasses the impact entrainment threshold. The differences in particle energy associated with these entrainment modes alter the transport dynamics of aeolian sand. Understanding these near-threshold behaviors is crucial to comprehensively understanding aeolian processes and accurately mitigating wind erosion hazards.