Nonequilibrium phase transition in the sedimentation of reproducing particles.
We study numerically and analytically the dynamics of a sedimenting suspension of active, reproducing particles, such as growing bacteria in a gravitational field. In steady state we find a nonequilibrium phase transition between a "sedimentation" regime, analogous to the sedimentation equilibrium of passive colloids, and a "uniform" regime, in which the particle density is constant in all but the top and bottom of the sample. We discuss the importance of fluctuations in particle density in locating the phase-transition point, and report the kinetics of sedimentation at early times.
SUPA and School of Physics, The University of Edinburgh, Mayfield Road, Edinburgh, EH9 3JZ, United Kingdom.
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Barrett-Freeman
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Evans
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Marenduzzo
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Poon