Front-propagating systems provide some of the most fundamental physical examples of interfacial instability and pattern formation. However, their nonlinear dynamics are rarely addressed. Here, we present an experimental study of air displacing a viscous fluid within a collapsed, compliant channel - a model system for pulmonary airway reopening. We show that compliance induces fingering instabilities absent in the rigid channel and we present the first experimental observations of the counter-intuitive 'pushing' behaviour previously predicted numerically, for which a reduction in air pressure results in faster flow. We find that pushing modes are unstable and moreover, that the dynamics of the air-fluid front involves a host of transient finger shapes over a significant range of experimental parameters.

中文翻译：

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顺从通道中的前端传播动力学

前向传播系统提供了界面不稳定性和图案形成的一些最基本的物理例子。然而，它们的非线性动力学很少得到解决。在这里，我们展示了空气置换塌陷的顺应性通道内的粘性流体的实验研究 - 肺气道重新开放的模型系统。我们表明顺应性会导致刚性通道中不存在的指法不稳定性，并且我们提出了先前以数字方式预测的反直觉“推动”行为的第一个实验观察结果，为此，气压的降低会导致更快的流动。我们发现推动模式是不稳定的，此外，空气-流体前沿的动力学涉及大量实验参数范围内的瞬态手指形状。