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SUMMARY:Macroscopic bundles of vortex rings in superfluid helium - Wacks\,
  D (Newcastle University)
DTSTART:20121206T153000Z
DTEND:20121206T154500Z
UID:TALK41889@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:It is well known that two co-axial vortex rings can leap-frog 
 about each other. By direct numerical simulation\, we show that in superfl
 uid helium the effect can be generalised to a large number of vortex rings
 \, which form a toroidal bundle. The bundle can be shown to be robust\, tr
 avelling a significant distance compared to its diameter\, whilst simultan
 eously becoming linked and eventually turbulent. We also discuss the effec
 t of friction at non-zero temperatures\, and show how in this case the pre
 sence of normal fluid rotation is necessary for the stability of the bundl
 e.\n
LOCATION:Seminar Room 1\, Newton Institute
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