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arXiv 0706.3140cond-mat.soft
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非布朗悬浮液中的Saffman-Taylor不稳定性:指选择和不稳定化

Saffman-Taylor instability in a non-Brownian suspension: finger selection and destabilization

C. Chevalier, A. Lindner, E. Clement

摘要:

本文研究了注入空气的非布朗悬浮液中的Saffman-Taylor不稳定性。我们发现,在Hele-Shaw细胞的流动结构可以描述的有效粘度取决于体积分数。当这个粘度被用来定义的不稳定性的控制参数,牛顿流体的经典手指选择恢复。然而,当单元厚度减小到低于约10个晶粒尺寸时,该图像就失效了。颗粒的离散性质也起着决定性的作用,在早期观察到的手指不稳定。晶粒在界面处产生与晶粒尺寸成比例的扰动,因此可以被认为是“受控噪声”。由Bensimon等人早先提出的有限振幅不稳定机制允许将这种扰动与不稳定阈值的实际值联系起来。

英文摘要:

We study the Saffman-Taylor instability in a non-Brownian suspension by injection of air. We find that flow structuration in the Hele-Shaw cell can be described by an effective viscosity depending on the volume fraction. When this viscosity is used to define the control parameter of the instability, the classical finger selection for Newtonian fluids is recovered. However, this picture breaks down when the cell thickness is decreased below approximatively 10 grain sizes. The discrete nature of the grains plays also a determinant role in the the early destabilization of the fingers observed. The grains produce a perturbation at the interface proportional to the grain size and can thus be considered as a "controlled noise". The finite amplitude instability mechanism proposed earlier by Bensimon et al. allows to link this perturbation to the actual values of the destabilization threshold.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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