Foams have unique properties that distinguish them from ordinary liquids and gases, and are ubiquitously observed in nature, both in biological systems and industrial products. Foams are known to eventually collapse over time; given their wide-range industrial application, understanding how bubbles in a foam collapse is an important aspect for product longevity and tailoring physical properties. Previously, it was shown that droplets are emitted during the collective bubble collapse, however the mechanism of the droplet emission in a foam is not yet clearly understood. It is directly related to the stability of the foam, thus we quantitatively investigate collapse dynamics in liquid films in a foam, and identify some unique features. When one film breaks, we see that the oscillation of the vertical Plateau border to which it is connected induces anomalous liquid transport from the edge of the border to the center. Once a crack appears near the border and a collapse front is formed, we find that the curvature of the front reverses as it migrates, followed by the emergence and emission of droplets. We elucidate the origins of this behavior and discuss the stability of foams, establishing how the characteristic time scales of the process relate to each other.

中文翻译：

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泡沫中液膜破裂的动力学和机理

泡沫具有独特的特性，使其与普通的液体和气体区别开来，并且在生物系统和工业产品的自然界中普遍存在。泡沫会随着时间的流逝最终崩溃。考虑到它们在工业上的广泛应用，了解泡沫如何破裂是确保产品寿命和调整物理性能的重要方面。以前，已经表明在集体气泡破裂期间会散发出小滴，但是还不清楚泡沫中液滴散发的机理。它与泡沫的稳定性直接相关，因此我们定量研究了泡沫中液膜的塌陷动力学，并确定了一些独特的功能。当一部电影破裂时，我们看到与之相连的垂直高原边界的振荡引起了从边界边缘到中心的异常液体传输。一旦裂纹出现在边界附近并且形成了坍塌的前沿，我们发现前沿的曲率随着其迁移而反向，随后液滴的出现和发射。我们阐明了这种行为的起源，并讨论了泡沫的稳定性，确定了该过程的特征时间尺度是如何相互关联的。