Simulation of aerodynamic entrainment with interparticle cohesions based on discrete element method,Earth Surface Processes and Landforms

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Simulation of aerodynamic entrainment with interparticle cohesions based on discrete element method
Earth Surface Processes and Landforms ( IF 2.8 ) Pub Date : 2021-03-04 , DOI: 10.1002/esp.5109
Shuming Jia _{1,

2} , Zhengshi Wang ₁

Affiliation

Aerodynamic entrainment acts as the pioneer of saltation movement and is critical for understanding the development of aeolian phenomena. In this study, air‐driven particles whose bottoms have left the bed surface were considered to be entrainment particles; this definition differs from the previous definition considering the initiation of rolling. We simulated the aerodynamic lifting of surface particles on a randomly oriented sedimentary bed using the discrete element method (DEM); we also proved that particles do not leave the bed vertically with speeds equal to the speed required to reach the height of one grain diameter, as is widely accepted. Rather, the particles were found to leave the bed at a much smaller angle and with much larger velocities with respect to the bed surface. The rate of entrainment exhibits an approximately linear dependence on the shear velocity, not a quadratic dependence, because the velocity of the entrained particles increases linearly with shear velocity. Moreover, the interparticle cohesion, which was found to increase the fluid entrainment threshold significantly, had no effect on the entrainment rate or on the take‐off velocity and angular distributions of the entrained particles. This is because the collisions between the entrained and bed particles destroy the interparticle bonds. Herein, we summarize a complete entrainment scheme based on DEM simulations, which provides a new approach for exploring the development and evolution of aeolian transportation processes.

中文翻译：

基于离散元方法的颗粒间内聚力气动夹带仿真

气动夹带是盐分运动的先驱，对于理解风沙现象的发展至关重要。在这项研究中，其底部离开床表面的空气驱动颗粒被认为是夹带颗粒。此定义与先前考虑开始滚动的定义不同。我们使用离散元方法（DEM）在随机定向的沉积床上模拟了表面颗粒的气动提升。我们还证明，粒子不会以与达到一个粒径的高度所需的速度垂直离开床的速度，这已被广泛接受。而是，发现颗粒以相对较小的角度和相对于床表面大得多的速度离开床。夹带速率表现出对剪切速度的近似线性依赖性，而不是二次依赖性，因为夹带颗粒的速度随剪切速度线性增加。此外，发现颗粒间的内聚力显着增加了流体的夹带阈值，对夹带速率或夹带颗粒的起飞速度和角度分布没有影响。这是因为夹带的颗粒和床颗粒之间的碰撞破坏了颗粒间的键。在此，我们总结了一个基于DEM模拟的完整夹带方案，该方案为探索风沙运输过程的发展和演变提供了一种新的方法。因为夹带粒子的速度随剪切速度线性增加。此外，发现颗粒间的内聚力显着增加了流体的夹带阈值，对夹带速率或夹带颗粒的起飞速度和角度分布没有影响。这是因为夹带的颗粒和床颗粒之间的碰撞破坏了颗粒间的键。在此，我们总结了一个基于DEM模拟的完整夹带方案，该方案为探索风沙运输过程的发展和演变提供了一种新的方法。因为夹带粒子的速度随剪切速度线性增加。此外，发现颗粒间的内聚力显着增加了流体的夹带阈值，对夹带速率或夹带颗粒的起飞速度和角度分布没有影响。这是因为夹带的颗粒和床颗粒之间的碰撞破坏了颗粒间的键。在此，我们总结了一个基于DEM模拟的完整夹带方案，该方案为探索风沙运输过程的发展和演变提供了一种新的方法。这是因为夹带的颗粒和床颗粒之间的碰撞破坏了颗粒间的键。在此，我们总结了一个基于DEM模拟的完整夹带方案，该方案为探索风沙运输过程的发展和演变提供了一种新的方法。这是因为夹带的颗粒和床颗粒之间的碰撞破坏了颗粒间的键。在此，我们总结了一个基于DEM模拟的完整夹带方案，该方案为探索风沙运输过程的发展和演变提供了一种新的方法。

更新日期：2021-03-24

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