Kondo Kurumi, Ebata Hiroyuki, Inagaki Shio
Department of Physics, Kyushu University, Fukuoka, 819-0395, Japan.
Sci Rep. 2023 Aug 18;13(1):13495. doi: 10.1038/s41598-023-40774-6.
Granular materials often segregate under mechanical agitation, which differs from the expectation of mixing. It is well known that a bidisperse mixture of granular materials in a partially filled rotating cylinder exhibits alternating bands depending on the combination of the two species. The dynamic angle of repose, which is the angle that a steady avalanche makes with the horizontal, has been considered the dominant parameter that determines the segregated state. However, the previously known angle of repose condition was not always satisfied in different experimental cases. To clarify the experimental conditions, we conducted an exhaustive parameter search with three dimensionless parameters: the particle size difference normalized by the average particle size, the specific density ratio, and the ratio of the cylinder diameter to the average particle size. Additional experiments were conducted to explore the effect of the rotational speed of the cylinder. This systematic approach enabled us to predict the segregated state. Moreover, we discovered that the band width can be effectively scaled by combining these three parameters.
粒状材料在机械搅拌下常常会发生离析，这与混合的预期情况不同。众所周知，部分填充的旋转圆筒中两种粒状材料的双分散混合物会根据两种物质的组合呈现出交替的条带。动态休止角是稳定雪崩与水平面所成的角度，一直被认为是决定离析状态的主要参数。然而，先前已知的休止角条件在不同的实验情况下并不总是满足。为了阐明实验条件，我们用三个无量纲参数进行了详尽的参数搜索：以平均粒径归一化的粒径差、比重比以及圆筒直径与平均粒径之比。还进行了额外的实验来探究圆筒转速的影响。这种系统的方法使我们能够预测离析状态。此外，我们发现通过组合这三个参数可以有效地对条带宽度进行标度。
