Abstract

A detailed study on similarities and differences of monodisperse dry and wet dense granular flow down on rough and smooth inclined planes was carried out by discrete element method simulations. Despite implementing a minimal model for capillary bridge cohesive force, all leading regimes of a granular flow, i.e. low-dissipation, high-dissipation, and oscillatory flow, can be developed in wet granular flow, similar to what we knew in the dry one. A smooth and rough based inclined planes as well as different inclination angels were used as parameters to create various flow regimes in dry and wet granular flow. In the oscillatory flow regime, the frequency of velocity profile variation is lower than that of the dry one. The velocity profile of the wet system in the low-dissipation flow regime exhibits an abrupt slope change at shear band bottom. As a measure of particle velocity fluctuations we have studied granular temperature in layers parallel to the inclined base. We found the temperature profile is increasing from the top to bottom, which means the shear band can be considered as a frozen region. By calculation of Radial Distribution Function (RDF) and using the adaptive Common Neighbor Analysis (a-CNA), the evolution of ordered/disordered structures in both dry and wet models is studied. In a wet system in the low-dissipation regime, the shear band exhibits frozen polycrystalline structure and in the bottom slice, in spite of having layered flow in the scale of one granule, we have a low fraction of crystallization. This study gives insightful key differences between wet and dry monodisperese granular flows, specifically the appearance of ordering and presence of crystalizations in different parts of high and low dissipation flow.

Graphic abstract

中文翻译：

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有序/无序单分散致密颗粒沿斜面流动：毛细管桥状态下的干介质与湿介质

摘要

通过离散元法模拟，详细研究了单分散干湿密颗粒在粗糙和光滑斜面上向下流动的异同。尽管实施了毛细管桥内聚力的最小模型，颗粒流的所有主要状态，即低耗散、高耗散和振荡流，都可以在湿颗粒流中发展，类似于我们在干流中所知道的。基于平滑和粗糙的斜面以及不同的倾角被用作参数，以在干湿颗粒流中创建各种流态。在振荡流态中，速度剖面变化的频率低于干流态。低耗散流态下湿系统的速度剖面在剪切带底部呈现陡峭的斜率变化。作为粒子速度波动的量度，我们研究了平行于倾斜底部的层中的颗粒温度。我们发现温度剖面从上到下逐渐增加，这意味着剪切带可以被认为是一个冻结区域。通过计算径向分布函数 (RDF) 并使用自适应公共邻域分析 (a-CNA)，研究了干湿模型中有序/无序结构的演变。在低耗散状态的湿系统中，剪切带表现出冻结的多晶结构，并且在底部切片中，尽管在一个颗粒的尺度上具有分层流动，但我们的结晶比例很低。这项研究给出了干湿单分散颗粒流之间深刻的关键差异，

图形摘要