Ratul Dasgupta (IIT Bombay, India)

Jets and wave focussing at the air-water interface

I will present an overview of a series of studies conducted in our group where we investigate wave focussing and jets arising from the natural oscillations of an air-water interface with a large deformation. In the first part of the talk, I will show that jets can be formed when the interface is  initially deformed as an axisymmetric Bessel function (a single) mode. A weakly nonlinear theory will be presented which can capture the initiation of the jet but proves inadequate to describe the jet itself. In the second part, similar results will be demonstrated for the shape eigenmode of a pinned bubble where it will be shown that large amplitude deformations of the bubble (shape modes) can also produce similar jets. The final example will be large amplitude deformation of the interface in the shape of a cavity. Here an analytical theory which can describe wave focussing will be explicitly demonstrated. Comparisons of theory will numerical simulations will be described in all cases.