Two-dimensional plastic flow of foams and emulsions in a channel: experiments and lattice Boltzmann simulations
Two-dimensional plastic flow of foams and emulsions in a channel: experiments and lattice Boltzmann simulations
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DOI：
10.1017/jfm.2015.28
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发表时间：
2015-02
影响因子：
3.7
通讯作者：
B. Dollet;A. Scagliarini;M. Sbragaglia
中科院分区：
文献类型：
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作者：
B. Dollet;A. Scagliarini;M. Sbragaglia
摘要为了理解复杂流体的流动剖面，一个关键的问题是在宏观水平上表现出协同性流动行为的塑性重排之间的空间相关性的出现。本文在Hele-Shaw几何条件下，对Poiffille流动中的塑性事件速率进行了实验测量。与独立测量的速度分布的相关性是量化的，通过查看的速度分布的本地化长度和塑性事件的空间分布的本地化长度之间的关系。为了补充泡沫中研究的协同机制与其他软玻璃态系统，我们比较实验与基于晶格玻尔兹曼方法，这是有和没有壁摩擦进行的致密乳液的模拟。最后，前所未有的结果分布的塑性事件的方向表明，有一个非平凡的相关性与潜在的局部剪切应变。这些特征以前没有报道过局限泡沫，进一步支持最初用于浓缩乳液的协同机制的想法（Goyon等人，Nature，vol.454，2008，pp. 84-87），在其他软玻璃质材料的行为中具有相似之处。
Abstract In order to understand the flow profiles of complex fluids, a crucial issue concerns the emergence of spatial correlations among plastic rearrangements exhibiting cooperativity flow behaviour at the macroscopic level. In this paper, the rate of plastic events in a Poiseuille flow is experimentally measured on a confined foam in a Hele-Shaw geometry. The correlation with independently measured velocity profiles is quantified by looking at the relationship between the localisation length of the velocity profiles and the localisation length of the spatial distribution of plastic events. To complement the cooperativity mechanisms studied in foam with those of other soft glassy systems, we compare the experiments with simulations of dense emulsions based on the lattice Boltzmann method, which are performed both with and without wall friction. Finally, unprecedented results on the distribution of the orientation of plastic events show that there is a non-trivial correlation with the underlying local shear strain. These features, not previously reported for a confined foam, lend further support to the idea that cooperativity mechanisms, originally invoked for concentrated emulsions (Goyon et al., Nature, vol. 454, 2008, pp. 84–87), have parallels in the behaviour of other soft glassy materials.