Condensed Matter Theory

Abstract:

Abstract:

© 2021, The Author(s), under exclusive licence to Springer Nature Limited. In the version of this Letter originally published online, the author J. M. Yeomans was incorrectly affiliated with ‘Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark’, instead of ‘Rudolf Peierls Centre for Theoretical Physics, Clarendon Laboratory, University of Oxford, Oxford, UK’. This affiliation has now been added, and other footnotes renumbered accordingly, in all versions of the Letter.

Abstract:

We use analytic arguments and numerical solutions of the continuum, active nematohydrodynamic equations to study how friction alters the behaviour of active nematics. Concentrating on the case where there is nematic ordering in the passive limit, we show that, as the friction is increased, memory effects become more prominent and +1/2 topological defects leave increasingly persistent trails in the director field as they pass. The trails are preferential sites for defect formation and they tend to impose polar order on any new +1/2 defects. In the absence of noise and for high friction, it becomes very difficult to create defects, but trails formed by any defects present at the beginning of the simulations persist and organise into parallel arch-like patterns in the director field. We show aligned arches of equal width are approximate steady state solutions of the equations of motion which co-exist with the nematic state. We compare our results to other models in the literature, in particular dry systems with no hydrodynamics, where trails, arches and polar defect ordering have also been observed.