Plateau-Rayleigh instability in a torus: formation and breakup of a polymer ring

A liquid jet can break up into a stream of droplets as a result of the Plateau-Rayleigh instability. The droplet formation decreases the jet's surface area and hence its free energy. Here we present the results of experiments in an unconventional geometry where this instability can be observed: a toroidal section. We discuss the formation of these polystyrene toroids with nanometer length scales. The constraints imposed by this geometry affect its observed instability in comparison to a simple linear jet. Specifically, we show that the additional curvature imposed by the torus can have a significant impact on the energy minimization route.