Visualization of Kelvin waves on quantum vortices
  In superfluid helium, vorticity is quantized and constrained on line-like phase singularities, called quantum or quantized vortices. By visualizing the motion of sub-micron frozen particles in superfluid $^{4}$He, we directly observe for the first time the helical Kelvin waves excited after quantized vortex reconnections. We compare the data with self-similar solutions of vortex filament models. We report the results in a fluid dynamic video. 
Enrico Fonda, David P. Meichle, Nicholas T. Ouellette, Sahand Hormoz,   Katepalli R. Sreenivasan, and Daniel P. Lathrop
physics.flu-dyn cond-mat.other