# Active matter invasion of a viscous fluid: Unstable sheets and a no-flow theorem.

@article{Miles2019ActiveMI, title={Active matter invasion of a viscous fluid: Unstable sheets and a no-flow theorem.}, author={Christopher J. Miles and Arthur A. Evans and Michael J. Shelley and Saverio E. Spagnolie}, journal={Physical review letters}, year={2019}, volume={122 9}, pages={ 098002 } }

We investigate the dynamics of a dilute suspension of hydrodynamically interacting motile or immotile stress-generating swimmers or particles as they invade a surrounding viscous fluid. Colonies of aligned pusher particles are shown to elongate in the direction of particle orientation and undergo a cascade of transverse concentration instabilities, governed at small times by an equation that also describes the Saffman-Taylor instability in a Hele-Shaw cell, or the Rayleigh-Taylor instability in…

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