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Issue 34, 2014
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Aggregation and segregation of confined active particles

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We simulate a model of self-propelled disks with soft repulsive interactions confined to a box in two dimensions. For small rotational diffusion rates, monodisperse disks spontaneously accumulate at the walls. At low densities, interaction forces between particles are strongly inhomogeneous, and a simple model predicts how these inhomogeneities alter the equation of state. At higher densities, collective effects become important. We observe signatures of a jamming transition at a packing fraction ϕ ∼ 0.88, which is also the jamming point for non-active athermal monodisperse disks. At this ϕ, the system develops a critical finite active speed necessary for wall aggregation. At packing fractions above ϕ ∼ 0.6, the pressure decreases with increasing density, suggesting that strong interactions between particles are affecting the equation of state well below the jamming transition. A mixture of bidisperse disks segregates in the absence of any adhesion, identifying a new mechanism that could contribute to cell sorting in embryonic development.

Graphical abstract: Aggregation and segregation of confined active particles

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The article was received on 29 Apr 2014, accepted on 23 Jun 2014 and first published on 24 Jun 2014

Article type: Paper
DOI: 10.1039/C4SM00927D
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Soft Matter, 2014,10, 6477-6484

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    Aggregation and segregation of confined active particles

    X. Yang, M. L. Manning and M. C. Marchetti, Soft Matter, 2014, 10, 6477
    DOI: 10.1039/C4SM00927D

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