EPL, 85 (2009) 18008
DOI: 10.1209/0295-5075/85/18008

Spontaneous flow states in active nematics: A unified picture

S. A. Edwards and J. M. Yeomans

The Rudolf Peierls Centre for Theoretical Physics - 1 Keble Road, Oxford, OX1 3NP, UK, EU

s.edwards1@physics.ox.ac.uk

received 21 October 2008; accepted in final form 1 December 2008; published January 2009
published online 13 January 2009

Abstract
Continuum hydrodynamic models of active liquid crystals have been used to describe dynamic self-organising systems such as bacterial swarms and cytoskeletal gels. A key prediction of such models is the existence of self-stabilising kink states that spontaneously generate fluid flow in quasi-one dimensional channels (VOITURIEZ R. et al Europhys. Lett., 70 (2005) 404). Using simple stability arguments and numerical calculations we extend previous studies to give a complete characterisation of the phase space for both contractile and extensile particles (i.e. pullers and pushers) moving in a narrow channel as a function of their flow alignment properties and initial orientation. This gives a framework for unifying many of the results in the literature. We describe the response of the kink states to an imposed shear, and investigate how allowing the system to be polar modifies its dynamical behaviour.

PACS
87.10.-e - Biological and medical physics: General theory and mathematical aspects.
83.80.Xz - Liquid crystals: nematic, cholesteric, smectic, discotic, etc.
47.60.-i - Flow phenomena in quasi-one-dimensional systems.

© EPLA 2009