Weaving tangled vortex webs: vortex knots, conservation of helicity and turbulent blobs
William Irvine (U. Chicago)
Vortices imbue flow with dynamism. Ever since Kelvin’s ’vortex atom’ hypothesis, tangled vortices and their topology have occupied a fundamental place in fluid mechanics. Knottiness - aka hydrodynamic or magnetic helicity has re-emerged as a conserved quantity in ideal fluids and plasmas, offering fundamental insights and radical new approaches to flow control. Turbulence and its eddies are fundamentally a complex vortex tangle representing the ultimate example of the central role of vorticity in flow. I will talk about experimental techniques to controllably weave vortex webs on demand, from isolated vortex knots and links to isolated blobs of turbulence. Observing their lively dynamics provides fundamental insights into how helicity can be surprisingly conserved in viscous flows and how turbulence can be assembled, controlled, and endowed with tunable cocktails of conserved quantities from `vortex Lego'.
Organizer
Sriram Ganeshan (CCNY/GC-CUNY)