Propagation of active nematic-isotropic interfaces on substrates

Abstract

Motivated by results for the propagation of active-passive interfaces of bacterial Serratia marcescens swarms [Nat. Comm., 9, 5373 (2018)] we use a hydrodynamic multiphase model to investigate the propagation of interfaces of active nematics on substrates. We characterize the active nematic phase of the model and discuss its description of the statistical dynamics of the swarms. We show that the velocicity correlation functions and the energy spectrum of the active turbulent phase of the model scale with the active length, for a range of activities. In addition, the energy spectrum exhibits two power-law regimes with exponents close to those reported for other models and bacterial swarms. Although the exponent of the rising branch of the spectrum (small wavevector) appears to be independent of the activity, the exponent of the decay changes with activity systematically, albeit slowly. We characterize also the propagation of circular and flat active-passive interfaces. We find that the closing time of the circular passive domain decays quadratically with the activity and that the structure factor of the flat interface is similar to that reported for swarms, with an activity dependent exponent. Finally, the effect of the substrate friction was investigated. We found an activity dependent threshold, above which the turbulent active nematic forms isolated islands that shrink until the system becomes isotropic and below which the active nematic expands, with a well defined propagating interface. The interface may be stopped by a fricion gradient.

References in corpus (13)

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• Meso-scale turbulence in living fluids
• Hydrodynamic fluctuations and instabilities in ordered suspensions of self-propelled particles
• Active matter
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• Biphasic, Lyotropic, Active Nematics
• Correlation lengths in hydrodynamic models of active nematics
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• The propagation of active-passive interfaces in bacterial swarms
• Curvature-dependent tension and tangential flows at the interface of motility-induced phases
• Active nematic-isotropic interfaces in channels
• Active Matter Invasion

Cited by in corpus (14)

• Active Turbulence
• Fingering Instability of Active Nematic Droplets
• Microbial Active Matter: A Topological Framework
• Dispersion of activity at an active-passive nematic interface
• Active nematics on flat surfaces: from droplet motility and scission to active wetting
• Asymmetric fluctuations and self-folding of active interfaces
• Scaling regimes of active turbulence with external dissipation
• Director alignment at the nematic-isotropic interface: elastic anisotropy and active anchoring
• Anisotropic disclination cores in nematic liquid crystals modelled by a self consistent molecular field theory
• Equilibrium morphology of tactoids in elastically anisotropic nematics
• Effect of anisotropy on the formation of active particle films
• Turbulence to order transitions in activity patterned active nematics
• Phase Separation in Mixtures of Nematic and Isotropic Fluids
• Conservation laws and slow dynamics determine the universality class of interfaces in active matter