The trunkenness of a volume-preserving vector field
  We construct a new invariant-the trunkenness-for volume-perserving vector fields on S^3 up to volume-preserving diffeomorphism. We prove that the trunkenness is independent from the helicity and that it is the limit of a knot invariant (called the trunk) computed on long pieces of orbits. 
Pierre Dehornoy (1), Ana Rechtman (2) ((1) IF, (2) UNAM)
math.DS astro-ph.SR math.GT physics.flu-dyn physics.plasm-ph