Although resonant motion of particles during mass flow discharge from silos has been extensively investigated by earlier researchers, the appearance of such phenomenon during funnel flow discharge has not been emphasized. In this work, the flow behavior of particles during funnel flow discharge from flat-bottomed silos has been investigated by conducting three-dimensional Discrete Element Method (DEM) simulations. It is found that particles in the upper part of flowing zone move collectively, manifested by the oscillatory fluctuations of the velocity and the non-Gaussian characteristics of the fluctuations of individual velocity around the average. Correlation analysis and discrete Fourier transform have been performed to characterize the emission and propagation of velocity fluctuation. It is found that the observed resonant motion of particles is induced by the regular fluctuation of contact force between particles, and there exists an intermediate region in the converging part of the flowing zone. The bottom boundary of this region corresponds to the emission source from which the velocity wave propagates upward and downward. Its upper boundary coincides with that of the converging part of the flowing zone and is featured by the most violent fluctuation of contact force. The simulation results thus suggest that the discharge of granular assembly seems to be determined by the rheological behavior of particles in this intermediate region.

中文翻译：

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平底筒仓漏斗流排放过程中颗粒的波动

尽管早期的研究人员已经广泛研究了筒仓质量流排放过程中颗粒的共振运动，但并未强调漏斗流排放过程中这种现象的出现。在这项工作中，通过进行三维离散元方法 (DEM) 模拟，研究了从平底筒仓漏斗流排放过程中颗粒的流动行为。发现流动区上部的粒子集体运动，表现为速度的振荡波动和个体速度在平均值附近波动的非高斯特征。相关分析和离散傅里叶变换已经被用来表征速度波动的发射和传播。发现观察到的粒子共振运动是由粒子间接触力有规律的波动引起的，在流动区的会聚部分存在一个中间区域。该区域的底部边界对应于速度波向上和向下传播的发射源。其上界与流动区的汇聚部分重合，接触力波动最为剧烈。因此，模拟结果表明颗粒集合的排放似乎是由该中间区域中颗粒的流变行为决定的。该区域的底部边界对应于速度波向上和向下传播的发射源。其上界与流动区的汇聚部分重合，接触力波动最为剧烈。因此，模拟结果表明颗粒集合的排放似乎是由该中间区域中颗粒的流变行为决定的。该区域的底部边界对应于速度波向上和向下传播的发射源。其上界与流动区的汇聚部分重合，接触力波动最为剧烈。因此，模拟结果表明颗粒集合的排放似乎是由该中间区域中颗粒的流变行为决定的。