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arXiv · 1304.2875

Confinement Stabilizes a Bacterial Suspension into a Spiral Vortex

Hugo Wioland·Francis G. Woodhouse·Jörn Dunkel·John O. Kessler·Raymond E. Goldstein
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Abstract

Confining surfaces play crucial roles in dynamics, transport and order in many physical systems, but their effects on active matter, a broad class of dynamically self-organizing systems, are poorly understood. We investigate here the influence of global confinement and surface curvature on collective motion by studying the flow and orientational order within small droplets of a dense bacterial suspension. The competition between radial confinement, self-propulsion, steric interactions and hydrodynamics robustly induces an intriguing steady single-vortex state, in which cells align in inwardly-spiralling patterns accompanied by a thin counterrotating boundary layer. A minimal continuum model is shown to be in good agreement with these observations.

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Hugo Wioland, Francis G. Woodhouse, Jörn Dunkel, John O. Kessler, Raymond E. Goldstein. 2013-04-10. Confinement Stabilizes a Bacterial Suspension into a Spiral Vortex. https://doi.org/10.1103/physrevlett.110.268102

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