Title: Tying and Untying Fluid Knots
Ideal fluid flows have an unusual conserved quantity, helicity, which measures the `knottedness' of the vortex lines composing a flow. In the absence of viscosity, vortex lines behave like closed pieces of unbreakable string: they may never cross, and so vortex knots stay tied. Although this concept has a long history for idealized fluids, far less is known about the behavior of vortex knots in real, non-ideal fluids. I will discuss the first experiments to study isolated vortex knots in experiment, which have revealed that -- paradoxically -- helicity may be conserved even though knots are intrinsically unstable. Finally, I will discuss recent work on knots in simulated superfluids which show similar dynamics despite the absence of viscosity.
Dustin Kleckner received his B.A. in Physics and Art from the University of Minnesota, Twin Cities in 2004. He attended UC Santa Barbara for his graduate studies, researching experimental quantum optomechanical systems in Dirk Bouwmeester's group. After receiving his Ph. D. in 2010, he moved to the University of Chicago to study soft matter physics and fluid mechanics, working in the groups of William Irvine and Sid Nagel. In 2015, he joined the faculty of UC Merced, where he is currently an assistant professor. His current research interests are in the origin of structure and geometrical effects in a wide range of systems, including fluid vortices, colloids, and other soft matter systems.
Every Friday 10:45-11:45 a.m., COB 267 (Please note the room change). Tea and cookies will be served from 10:30 - 10:45 a.m. Questions regarding the seminar series should be directed to Prof. Bin Liu