Tuesday, July 23, 2013

1307.5721 (M. Leoni et al.)

Synchronisation and liquid crystalline order in soft active fluids    [PDF]

M. Leoni, T. B. Liverpool
We introduce a phenomenological theory for a new class of soft active fluids, with the ability to synchronise. Our theoretical framework describes the macroscopic behaviour of a collection of interacting anisotropic elements with cyclic internal dynamics and a periodic phase variable. This system (i) can spontaneously undergo a transition to a state with macroscopic orientational order, with the elements aligned: a liquid crystal, (ii) attain another broken symmetry state characterised by synchronisation of their phase variables or (iii) a combination of both types of order. We derive the equations describing a spatially homogeneous system and also study the hydrodynamic fluctuations of the soft modes in some of the ordered states. We find that synchronisation can promote the transition to a state with orientational order; and vice-versa. Finally, we provide an explicit microscopic realisation: a suspension of micro-swimmers driven by cyclic strokes.
View original: http://arxiv.org/abs/1307.5721

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