Hemingway, E.J. and Cates, M.E. and Fielding, S.M. (2016) 'Viscoelastic and elastomeric active matter : linear instability and nonlinear dynamics.', Physical review E., 93 (3). 032702.
We consider a continuum model of active viscoelastic matter, whereby an active nematic liquid crystal is coupled to a minimal model of polymer dynamics with a viscoelastic relaxation time τC. To explore the resulting interplay between active and polymeric dynamics, we first generalize a linear stability analysis (from earlier studies without polymer) to derive criteria for the onset of spontaneous heterogeneous flows (strain rate) and/or deformations (strain). We find two modes of instability. The first is a viscous mode, associated with strain rate perturbations. It dominates for relatively small values of τC and is a simple generalization of the instability known previously without polymer. The second is an elastomeric mode, associated with strain perturbations, which dominates at large τC and persists even as τC→∞. We explore the dynamical states to which these instabilities lead by means of direct numerical simulations. These reveal oscillatory shear-banded states in one dimension and activity-driven turbulence in two dimensions even in the elastomeric limit τC→∞. Adding polymer can also have calming effects, increasing the net throughput of spontaneous flow along a channel in a type of drag reduction. The effect of including strong antagonistic coupling between the nematic and polymer is examined numerically, revealing a rich array of spontaneously flowing states.
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|Publisher Web site:||http://dx.doi.org/10.1103/PhysRevE.93.032702|
|Publisher statement:||Reprinted with permission from the American Physical Society: Physical Review E 93, 032702 © (2016) by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modified, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.|
|Date accepted:||24 February 2016|
|Date deposited:||29 March 2016|
|Date of first online publication:||15 March 2016|
|Date first made open access:||29 March 2016|
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