Elastic amplification of the Rayleigh-Taylor instability in solidifying melts
Elastic amplification of the Rayleigh-Taylor instability in solidifying melts
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DOI：
10.1073/pnas.2020701118
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发表时间：
2021-03-09
影响因子：
11.1
通讯作者：
Brun, P-T
中科院分区：
文献类型：
--
作者：
Jambon-Puillet, Etienne;Piechaud, Matthieu Royer;Brun, P-T
伴随的熔体的机械变形和凝固与广泛的现象有关。例子包括棉花糖的制备，金属的雾化，玻璃纤维的制造，以及在火山爆发中形成被称为贝利头发的细长结构。通常，在凝固过程中的类固体变形被忽略，因为熔体在其初始的类液体形式下更具延展性。在这里，我们展示了如何在凝固过程中的弹性变形，即，而熔体响应为非常软的固体（G类似于100 Pa），可导致形成先前未知的周期性结构。也就是说，我们通过瑞利-泰勒不稳定性在旋转圆柱体外部涂覆的液体弹性体熔体薄层上产生液滴阵列。然后，随着熔体固化并通过其凝胶点，旋转速度增加，液滴拉伸成头发。持续的固化最终使材料硬化，将这些弹性变形永久地“冻结”成图案化的固体。使用实验，模拟和理论，我们证明，我们的两步模式的形成可以合理化时，结合从流体力学，弹性和统计学的工具。因此，我们的研究提供了一个框架来分析多步图案形成过程，并利用它们来组装复杂的材料。
The concomitant mechanical deformation and solidification of melts are relevant to a broad range of phenomena. Examples include the preparation of cotton candy, the atomization of metals, the manufacture of glass fibers, and the formation of elongated structures in volcanic eruptions known as Pele's hair. Usually, solid-like deformations during solidification are neglected as the melt is much more malleable in its initial liquid-like form. Here we demonstrate how elastic deformations in the midst of solidification, i.e., while the melt responds as a very soft solid (G similar to 100 Pa), can lead to the formation of previously unknown periodic structures. Namely, we generate an array of droplets on a thin layer of liquid elastomer melt coated on the outside of a rotating cylinder through the Rayleigh-Taylor instability. Then, as the melt cures and goes through its gelation point, the rotation speed is increased and the drops stretch into hairs. The ongoing solidification eventually hardens the material, permanently "freezing" these elastic deformations into a patterned solid. Using experiments, simulation, and theory, we demonstrate that the formation of our two-step patterns can be rationalized when combining the tools from fluid mechanics, elasticity, and statistics. Our study therefore provides a framework to analyze multistep pattern formation processes and harness them to assemble complex materials.