Physics Colloquium: Barriers to front propagation and active transport in laminar fluid flows
Tuesday, October 10 at 3:15pm
Regents Hall, 109 3700 O St. NW
Tom Solomon, Department of Physics, Bucknell University
Abstract: We present experiments on the effects of vortex-dominated flows on the spreading of the excitable Belousov-Zhabotinsky chemical reaction and on the motion of bacteria. The results of these experiments have applications for a wide range of systems including microfluidic chemical reactors, cellular-scale processes in biological systems, and blooms of phytoplankton in the oceans. To predict the behavior of reaction fronts, we adapt tools used to describe chaotic fluid mixing in laminar flows.In particular, we propose "burning invariant manifolds" (BIMs) that act as one-way barriers that locally block the motion of reaction fronts and "smooth swimming" bacillus subtilus. These ideas are tested and illustrated experimentally in a chain of alternating vortices, a spatially-random flow, vortex flows with imposed winds, a three-dimensional, nested vortex flow, and a hyperbolic microfluidic flow.
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