Title: Thread pinch-off: asymmetric cones in viscous flow.
Speaker: Wendy Zhang
Speaker Info: University of Chicago
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Dynamic singularities are ubiquitous. They arise in mathematical models of phenomena as grand as star formation or as familiar as the pinching of a thread of honey as it is being added to tea. Thread pinch- off allows one to study dynamics close to a singularity in a simple context which is also accessible to experiments. Recent works have revealed that a viscous thread close to pinch-off looks self-similar--- the thread profile looks the same if the lengthscales are rescaled appropriately. Surprisingly, the presence of even small amounts of viscous dissipation in the surrounding can dramatically alter the self- similar profile. In particular, when no exterior viscous dissipation is present, the thread profile is symmetric about the point of pinch-off. When small amounts of exterior viscous dissipation are present, the thread profile becomes severely asymmetric. The precise origin of this asymmetry remains a puzzle.Date: Friday, January 25, 2002