Abstract:
A traditional and powerful method for studying the behavior of thin liquid sheets is to harness the analogy to elastic media. However, in rapidly evolving viscous films this analogy is broken. I will show that for this case, the film evolves through a geometrically nonlinear dynamics, where the driving mechanism is the flow of currents of Gaussian curvature, rather than the existence of an energetically preferred target metric. I will demonstrate the dynamics by studying the collapse of a rapidly depressurized bubble. The film evolves by triggering a topological instability, which is forbidden in the elastic analog and creates a moving “ridge” in the liquid film. In turn, the propagating front triggers a symmetry-breaking instability to wrinkle formation. I will discuss why these dynamics should appear in additional systems as well, such as viscous electron flows in graphene.