沙粒起跃的动态模拟

沙粒起跃规律是风沙运动微观机理研究和宏观工程应用相联系的纽带,目前进展缓慢且不成熟。本文建立了简洁的沙粒碰撞模型,构造了单颗沙粒以11.5°的碰撞角高速撞击由9000个沙粒组成的沙床的计算机实验,以10^-6秒为时间步长精细模拟了被碰沙粒起跃的全过程,对起跃沙粒的空间分布、速度大小和方向以及入射沙粒速度的影响进行了细致研究,其中起跳速度大小符合指数分布,与已知观测结果符合较好。

Simulation of Dynamic Behavior of Saltation Grains from Loose Sedimentary Beds

Saltation, as the most important motion of blown sand grains, plays a vital role in building the bridge between intrinsic mechanism exploration and engineering application of sediment research. Important progress has been made in the recent years in determining speed distribution function of the lift-off particles, especially by numerical simulation. However, there are still many problems remained. A simple but more realistic collision model for grains is presented in this paper, with which the dynamic behavior of saltation particles from loose sedimentary bed is simulated by launching a particle onto the surface. The impacting angle and time interval are fixed at 11.5° and 10^-6 second respectively. Detailed discussion of saltation velocity is made, including spatial distribution; especially the magnitude distribution fits exponential regression very well, which is in good agreement with the previous experimental result. All these results in this work are helpful for understanding saltation process in aeolian sediment transport.