基于离散元模拟的沙粒大小颗粒碰撞倾斜颗粒床的飞溅函数,Powder Technology

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基于离散元模拟的沙粒大小颗粒碰撞倾斜颗粒床的飞溅函数
Powder Technology ( IF 4.5 ) Pub Date : 2021-01-01 , DOI: 10.1016/j.powtec.2020.10.008
Xin Yin , Ning Huang , Cong Jiang , Eric J.R. Parteli , Jie Zhang

摘要这项工作的动机是缺乏与风吹沙粒碰撞到倾斜颗粒表面相关的飞溅函数模型。这个飞溅函数描述了反弹粒子的速度以及喷射粒子的数量和速度，是沙子输送和沙丘和波纹形成的理论模型的重要组成部分。虽然以前的模型将颗粒床视为水平面，但有实验证据表明床坡会影响飞溅过程。然而，由于很难通过实验研究床附近的粒子轨迹，解决单个粒子轨迹的数值模拟为阐明床坡对飞溅函数的影响提供了有用的手段。在这里，我们通过离散元方法 (DEM) 使用数值模拟来研究沙粒大小的颗粒撞击倾斜床的飞溅函数。为此，我们认为河床坡度与波纹和沙丘迎风面的坡度一致。具体而言，颗粒床与水平面之间的角度 θ 从 0° 到 15° 不等，同时考虑了宽范围的颗粒冲击速度（从 1 m/s 到 7 m/s）。此外，我们考虑的入射粒径 din 值在 120 ≤ din/μm ≤ 520 范围内，即与天然砂一致。我们获得了作为入射粒子直径和速度以及床坡度的函数的飞溅函数的所有参数的表达式。特别是，

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Splash function for the collision of sand-sized particles onto an inclined granular bed, based on discrete-element-simulations

Abstract This work is motivated by the lack of a model for the splash function associated with the collision of wind-blown sand grains onto an inclined granular surface. This splash function, which describes the velocity of rebound particles and the number and velocity of ejected particles, is an essential ingredient of theoretical models of sand transport and the formation of dunes and ripples. While previous models regarded the granular bed as a horizontal surface, there is experimental evidence that bed slopes can affect the splash process. However, since it is difficult to investigate particle trajectories near the bed from experiments, numerical simulations that resolve individual particle trajectories provide useful means to elucidate the effect of bed slope on the splash function. Here we employ numerical simulations by means of the Discrete-Element-Method (DEM) to investigate the splash function of sand-sized particles impacting onto inclined beds. To this end, we consider bed slopes consistent with those of the windward side of ripples and dunes. Specifically, the angle θ between the granular bed and the horizontal is varied from 0° to 15°, while a broad range of particle impact velocities (from 1 m/s to 7 m/s) is considered. Moreover, we consider values of incident particle diameter din within the range 120 ≤ din/μm ≤ 520, i.e., consistent with natural sand. We obtain expressions for all parameters of the splash function as a function of the incident particle diameter and velocity, and the bed slope. In particular, our simulations show that the effect of the bed slope on the splash function depends on the size of the impacting particle, which has implication for grain trajectories formative of ripples and dunes.

更新日期：2021-01-01

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