Coherent laminar and turbulent motion of toroidal vortex bundles
  Motivated by experiments performed in superfluid helium, we study numerically the motion of toroidal bundles of vortex filaments in an inviscid fluid. We find that the evolution of these large-scale vortex structures involves the generalised leapfrogging of the constituent vortex rings. Despite three dimensional perturbations in the form of Kelvin waves and vortex reconnections, toroidal vortex bundles retain their coherence over a relatively large distance (compared to their size), in agreement with experimental observations. 
D.H. Wacks, A.W. Baggaley, C.F.Barenghi
physics.flu-dyn cond-mat.other