BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Carlo Barenghi (Newcastle University - UK) DTSTART:20221118T160000Z DTEND:20221118T170000Z DTSTAMP:20260423T022915Z UID:GEOTOP-A/28 DESCRIPTION:Title: Is turbulence knotted?\nby Carlo Barenghi (Newcastle University - UK ) as part of GEOTOP-A seminar\n\n\nAbstract\nVortex lines and streamlines in turbulent flows\, visualized in the experiments or in the numerics\, ap pear chaotic\, twisted\, perhaps linked or knotted. The physical meaning o f this complexity and its relation to the dynamics is still obscure. In th is lecture I shall address this problem - the geometrical and topological complexity of turbulence - in the arguably simpler context of "quantum flu ids".\n\nQuantum fluids (superfluid helium\, atomic Bose-Einstein condensa tes\, etc)are studied in the laboratory at temperatures close to absolute zero. At these low temperatures the fundamental quantum properties of matt er are not masked by thermal disorder. In particular\, any rotational mot ion is constrained by quantum mechanics to individual vortex lines of fixe d strength (phase defects of a complex order parameter)\, unlike what happ ens in ordinary fluids where vorticity is a continuous field. Quantum turb ulence\, created by stirring a quantum fluid\, is thus conceptually simple r than ordinary turbulence\, consisting of a tangle of individual vortex l ines rather than a disordered continuous vorticity field.\n\nAfter describ ing some surprising similarities between quantum turbulence and ordinary t urbulence\, I shall show how the geometry and the topology of quantum turb ulence can be quantified in a relatively simple way\, hence demonstrate th at quantum turbulence is indeed knotted. Is ordinary turbulence knotted to o?\n LOCATION:https://researchseminars.org/talk/GEOTOP-A/28/ END:VEVENT END:VCALENDAR