Particle-size segregation patterns in a partially filled triangular rotating drum
Particle-size segregation patterns in a partially filled triangular rotating drum
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DOI：
10.1017/jfm.2023.1022
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发表时间：
2024-01
影响因子：
3.7
通讯作者：
E. S. F. Maguire;T. Barker;M. Rauter;C. Johnson;J. Gray
中科院分区：
文献类型：
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作者：
E. S. F. Maguire;T. Barker;M. Rauter;C. Johnson;J. Gray
本文采用全耦合颗粒流分离模型(Barker等人，《流体力学》，第909卷，2021，A22页)模拟了三角形旋转转鼓内颗粒分布的发展过程。将结果与双分散和三分散颗粒混合物在不同组成和填充高度下形成的实验图案进行了比较。在所有情况下，模拟和实验之间的一致性都非常好。实验图案是在透明的前壁和后壁之间的狭窄间隙中产生的。这阻止了三维运动，但也对流动施加了摩擦力，使其变得更薄、更快。这促进了偏析，因为它同时增加了剪切速率并减少了局部压力。为了获得正确的流动动力学和分离，在二维模拟中加入了平均侧壁阻力，并在OpenFOAM中进行了计算。自由表面的雪崩形成了一个边界层，在这个边界层内发生了所有的偏析。雪崩下游的物质不断地沉积到下面的固体颗粒中，颗粒与滚筒一起旋转，最终沿着雪崩的上游重新卷进雪崩。颗粒状区域不断变化的几何形状(随着滚筒的旋转)意味着雪崩正在不断地调整其长度、位置和深度。这产生了一种复杂的准周期流动，当它与颗粒大小分离结合在一起时，只需两次转鼓就能在固体旋转的颗粒体中产生令人惊叹的图案。
Abstract In this paper a fully coupled particle-size segregation model for granular flows (Barker et al., J. Fluid Mech., vol. 909, 2021, p. A22) is used to simulate the development of the patterns in a triangular rotating drum. The results are compared with the experimental patterns formed with bidisperse and tridisperse granular mixtures, and with varying compositions and fill heights. In all cases the agreement between the simulations and experiments is remarkably good. The experimental patterns are generated in a narrow gap between transparent front and back sidewalls. These prevent three-dimensional motion, but also impose friction on the flow, making it thinner and faster than it would otherwise be. This promotes segregation, as it simultaneously increases the shear rate and reduces the local pressure. To obtain the correct flow dynamics and segregation, width-averaged sidewall friction is incorporated into the two-dimensional simulations, which are performed in OpenFOAM$^{\circledR}$. The free-surface avalanche forms a boundary layer within which all the segregation occurs. Material in the lower reach of the avalanche is continuously deposited into an underlying solid body of grains, which rotates with the drum, and is eventually re-entrained into the avalanche along its upper reach. The changing geometry of the granular region (as the drum rotates) implies that the avalanche is constantly adjusting its length, position and depth. This generates a complex quasi-periodic flow, which when combined with particle-size segregation generates amazing patterns in the solid rotating granular body after only two drum rotations.