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首页> 外文期刊>Journal of Geophysical Research, D. Atmospheres: JGR >Particle dynamics method simulations of stochastic collisions of sandy grain bed with mixed size in aeolian sand saltation
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Particle dynamics method simulations of stochastic collisions of sandy grain bed with mixed size in aeolian sand saltation

机译：风沙盐化过程中混合尺寸沙粒床随机碰撞的粒子动力学模拟。

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This paper presents a statistical approach to predict the behavior of liftoff grains on the basis of simulation of random collisions between incident grains and the mixed sand bed by means of the particle dynamics method (PDM). In the simulation a two-dimensional sand bed of grain-grain contact between the mixed size grains, which are simplified by circular disks, is stochastically generated by a random number generator and the “particle cooling” technique. After the diameter distribution of incident grains is divided into n subregions of representative diameters, first, the collisions are simulated for each representative diameter of incident grains with an incident velocity impacting the mixed sand bed, for which the information about liftoff grains may be gained at the end of collisions. After that a statistic approach is proposed to get the average values of velocity and number of the ejecting and rebounding grains as well as the probability density function (pdf) of liftoff velocity in terms of magnitude and angle. In order to guarantee steady state of the statistical quantities, 110 samples of the random collisions of each representative diameter of grains with an incident velocity but different (or random) contact position are taken in a case study in which the average diameter of the grains is the same as that of the uniform sand grains employed by Anderson and Haff (1991). The numerical results show that there are notable differences in the statistical quantities between them, and some of the results obtained here are in good agreement with the measurement data of multiple grain size. Finally, the pdf of initial velocity in terms of both magnitude and angle is derived on the basis of the simulation results.
机译：本文利用粒子动力学方法（PDM），通过模拟入射颗粒与混合砂床之间的随机碰撞，提出了一种统计方法来预测剥离颗粒的行为。在模拟中，通过随机数生成器和“粒子冷却”技术随机生成了混合颗粒之间的二维沙床，这些颗粒通过圆盘简化了混合。将入射颗粒的直径分布划分为代表直径的n个子区域后，首先，针对入射颗粒的每个代表直径模拟碰撞，其中入射速度会影响混合砂床，为此可以在以下位置获得有关剥离颗粒的信息：碰撞的结束。此后，提出了一种统计方法来获取速度和弹起和反弹的晶粒数的平均值，以及在幅度和角度方面的提离速度的概率密度函数（pdf）。为了保证统计量的稳定状态，在一个案例研究中，对110个具有代表性的晶粒的随机碰撞进行了采样，每个晶粒的入射速度均具有入射速度，但接触位置不同（或随机）。与Anderson和Haff（1991）使用的均匀砂粒相同。数值结果表明，它们之间的统计量存在显着差异，并且此处获得的一些结果与多种晶粒尺寸的测量数据非常吻合。最后，根据仿真结果得出了初始速度的pdf（大小和角度）。

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