Edge-state mediated front propagation in compliant channels

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, moreover, that the dynamics of the air-fluid front are dominated by a host of unstable modes over a significant range of experimental parameters.