A fluidized bed is basically a suspension of granular material by an ascending fluid in a tube, and it has a rich dynamics that includes clustering and pattern formation. When the ratio between the tube and grain diameters is small, different behaviors can be induced by high confinement effects. Some unexpected and curious behaviors, that we investigate in this paper, are the crystallization and jamming of grains in liquids with velocities higher than that for incipient fluidization, supposed to maintain the grains fluidized. In our experiments, performed in a vertical tube of transparent material, different grains, water velocities, resting times, and velocity decelerations were used. An analysis of the bed evolution based on image processing shows that, after a decreasing flow that reaches a velocity still higher than that for incipient fluidization, grains become organized in lattice structures of high compactness, where they are trapped though with small fluctuations. These structures are initially localized and grow along time, in a similar manner as happens in phase transitions and glass formation. After a certain time, if the liquid velocity is slightly increased, jamming occurs, with grains being completely blocked and their fluctuation disappearing. We show that different lattice structures appear depending on the grain type. Our results provide new insights into fluidization conditions, glass-like formation and jamming.

中文翻译：

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狭窄流化床中的结晶和堵塞

流化床基本上是由管中上升的流体悬浮的颗粒材料，它具有丰富的动力学，包括聚集和图案形成。当管径与晶粒直径之比较小时，高限制效应会引起不同的行为。我们在本文中研究的一些意外和奇怪的行为是颗粒在液体中的结晶和堵塞，其速度高于初始流化的速度，应该保持颗粒流化。在我们的实验中，在透明材料的垂直管中进行，使用了不同的颗粒、水速、静止时间和速度减速。基于图像处理的床层演化分析表明，在流速下降，流速仍高于初始流化时，晶粒组织成高度致密的晶格结构，尽管波动很小，但仍被困住。这些结构最初是局部的，并随着时间的推移而增长，其方式与相变和玻璃形成中发生的方式类似。一定时间后，如果液体速度稍有增加，就会发生堵塞，颗粒被完全堵塞，波动消失。我们表明根据晶粒类型出现不同的晶格结构。我们的结果为流化条件、玻璃状形成和堵塞提供了新的见解。这些结构最初是局部的，并随着时间的推移而增长，其方式与相变和玻璃形成中发生的方式类似。一定时间后，如果液体速度稍有增加，就会发生堵塞，颗粒被完全堵塞，波动消失。我们表明根据晶粒类型出现不同的晶格结构。我们的结果为流化条件、玻璃状形成和堵塞提供了新的见解。这些结构最初是局部的，并随着时间的推移而增长，其方式与相变和玻璃形成中发生的方式类似。一定时间后，如果液体速度稍有增加，就会发生堵塞，颗粒被完全堵塞，波动消失。我们表明根据晶粒类型出现不同的晶格结构。我们的结果为流化条件、玻璃状形成和堵塞提供了新的见解。