Inertial collapse of liquid rings

Liquid rings can be generated in the Leidenfrost state using liquid oxygen of low boiling point ($- 183~\textdegree \mathrm{C} $) and high magnetic susceptibility, allowing one to ‘sculpt’ the liquid into a ring shape using an annular magnet. When the magnetic field is turned off, the ring shrinks back into a puddle with a constant acceleration. A potential flow approach accurately describes the dynamics of closure with an equation reminiscent of the Rayleigh–Plesset equation for the collapse of transient cavities.