Rising obstacle in a one-layer granular bed induced by continuous vibrations: two dynamical regimes governed by vibration velocity
Rising obstacle in a one-layer granular bed induced by continuous vibrations: two dynamical regimes governed by vibration velocity
复制标题
连续振动引起的一层颗粒床中上升的障碍物：由振动速度控制的两种动力学状态
DOI：
10.1039/d0sm01021a
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发表时间：
2020
期刊：
影响因子：
3.4
通讯作者：
Okumura Ko
中科院分区：
文献类型：
--
作者：
Then Hui Zee;Sekiguchi Teruyo;Okumura Ko
在振动的颗粒介质中，障碍物的上升运动是一个典型的颗粒偏析问题，被称为巴西坚果效应。控制振动参数的辨识是一个长期存在的问题。最近有人指出，BN效应可以只用振动速度来表征的简单可能性。在漫长的研究历史中，这个问题一直备受争议，只有少数系统为这种简单的可能性提供了证据。在这里，我们研究了连续振动下垂直放置的单层颗粒床中障碍物的上升运动。我们发现上升运动由两种不同的状态组成，第一和第二状态都是由振动参数决定的，仅由振动速度决定。我们进一步证明了简单的标度定律，很好地描述了这两种状态。我们的研究结果支持了BN效应控制参数的简单可能性，并表明这一特征可能是普遍的。我们提出了对流和拱效应两种可能的机制，并证明了这些机制解释了我们实验数据遵循的标度定律。
The rising motion of an obstacle in a vibrated granular medium is a classic problem of granular segregation, and called the Brazil nut (BN) effect. Identification of the controlling vibration parameters of the effect is a long-standing problem. The simple possibility that the BN effect can be characterized solely by vibration velocity has recently been pointed out. The issue has become controversial over the long history of research, with only a few systems providing evidence for this simple possibility. Here, we investigate the rising motion of an obstacle in a vertically positioned one-layer granular bed under continuous vibrations. We find the rising motion is composed of two distinct regimes, and the first and second regimes are both governed, in terms of vibration parameters, solely by the vibration velocity. We further demonstrate simple scaling laws that well describe the two regimes. Our results support the emergent simple possibility for the controlling parameters of the BN effect and suggest that this feature could be universal. We propose two possible mechanisms of convection and arch effect for the two distinct regimes and demonstrate that these mechanisms explain the scaling laws followed by our experimental data.