Pressure-driven changes to spontaneous flow in active nematic liquid crystals

Joshua Walton, Geoffrey McKay, Michael Grinfeld, Nigel J. Mottram

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4 Citations (Scopus)
63 Downloads (Pure)


We consider the effects of a pressure gradient on the spontaneous flow of active nematic liquid crystal in a channel, subject to planar anchoring and no-slip conditions on the boundaries of the channel. We employ a model based on the Ericksen-Leslie theory of nematics, with an additional active stress accounting for the activity of the fluid. By directly solving the flow equation, we consider an asymptotic solution for the director angle equation for large activity parameter values and predict the possible values of the director angle in the bulk of the channel. Through a numerical solution of the full nonlinear equations, we examine the effects of pressure on the branches of stable and unstable equilibria, some of which are disconnected from the no-flow state. In the absence of a pressure gradient, solutions are either symmetric or antisymmetric about the channel midpoint; these symmetries are changed by the pressure gradient. Considering the activity-pressure state space allows us to predict qualitatively the extent of each solution type and to show, for large enough pressure gradients, that a branch of non-trivial director angle solutions exists for all activity values.
Original languageEnglish
Article number51
Number of pages14
JournalEuropean Physical Journal E - Soft Matter
Issue number8
Early online date4 Aug 2020
Publication statusE-pub ahead of print - 4 Aug 2020


  • liquid crystals
  • swimming microorganisms
  • continuum models and theory of liquid crystal structure


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