Enhanced diffusion due to active swimmers at solid surfaces
Condensed Matter journal club
Enhanced diffusion due to active swimmers at solid surfaces
- Event time: 11:30am
- Event date: 12th November 2010
- Speaker: Vincent Martinez (Formerly School of Physics & Astronomy, University of Edinburgh)
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
Event details
We consider two systems of active swimmers moving close to a solid surface, one being a living
population of wild-type E. coli and the other being an assembly of self-propelled Au-Pt rods. In both situations
we have identified two different types of motion at the surface and evaluated the fraction of the population that
displayed ballistic trajectories (active swimmers) with respect to those showing diffusive-like behaviour. We studied the
effect of this complex swimming activity on the diffusivity of passive tracers also present on the surface. We found that the tracer diffusivity is
enhanced with respect to standard Brownian motion and increases linearly with the activity of the
fluid, defined as the product of the fraction of active swimmers and their mean velocity. This result can be understood in terms of series of elementary encounters between the active swimmers and the
tracers.
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Given the diversity of research in the CM group, chosen topics vary widely. We tend to stick to high-impact journals - Nature, Science, PNAS and PRL have been popular - but this is not prescriptive..