Abstract

Mixing and segregation of binary mixtures of freely-falling grains are demonstrated in a cylindrical pipe with an obstacle. Previously, the same setup was used to spatially focus monodisperse granular materials. As each grain is dropped one at a time from a random position at the entrance of the cylindrical pipe, it may collide with a steady or oscillating obstacle and the wall. We performed a time-driven multi-scale simulation and use Routh’s impact model for collisions to show that the focusing of grains for monodisperse granular materials is dependent on the geometry of the pipe, the elastic properties of the grain, and the amplitude of oscillation of the obstacle. For binary granular mixtures, segregation may be achieved when the elastic properties of the grain species have a big difference. However, the efficiency of segregation is diminished when the amplitude of obstacle oscillation is increased, leading to granular mixing. Just as a high degree of segregation can be attained with a stationary obstacle, a high degree of mixing can be obtained with a moving obstacle.

Graphic abstract

中文翻译：

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自由下落的颗粒状物料通过垂直管道混合和分离

摘要

自由下落的颗粒的二元混合物的混合和分离在带有障碍物的圆柱管中得到证明。以前，相同的设置用于空间聚焦单分散颗粒材料。由于每种谷物每次都从圆柱管入口处的随机位置一次掉落，可能会与稳定的或摆动的障碍物和壁碰撞。我们执行了时间驱动的多尺度模拟，并使用Routh碰撞模型进行了碰撞研究，结果表明，单分散颗粒材料的颗粒聚焦取决于管道的几何形状，颗粒的弹性以及振动幅度。障碍。对于二元颗粒混合物，当颗粒物质的弹性性质差异较大时，可以实现偏析。然而，当障碍物振荡的幅度增加时，分离效率降低，从而导致颗粒混合。正如在静止的障碍物下可以实现高度隔离一样，在运动的障碍物下也可以实现高度混合。

图形摘要