Following fluctuating signs: anomalous active superdiffusion of swimmers in anisotropic media

Abstract

Active (i.e., self-propelled or swimming) particles moving through an isotropic fluid exhibit conventional diffusive behavior. We report anomalous diffusion of an active particle moving in an anisotropic, nematic background. Whilst the translational motion parallel to the nematic director shows ballistic behavior, the long-time transverse motion is super-diffusive, with an anomalous scaling $\propto t\ln t$ of the mean squared displacement with time $t$. This behavior is predicted by an analytical theory that we present here, and is corroborated by numerical simulation of active particle diffusion in a simple lattice model for a nematic liquid crystal. It is universal for any collection of self-propelled elements (e.g., bacteria or active rods) moving in a nematic background, provided only that the swimmers are sufficiently dilute that their interactions with each other can be neglected, and that they do not perform "hairpin" turns.

12 pages, 3 figures

References in corpus (11)

• Physics of Microswimmers - Single Particle Motion and Collective Behavior
• Fluid dynamics and noise in bacterial cell-cell and cell-surface scattering
• Flagellated bacterial motility in polymer solutions
• Dynamics of self-propelled Janus particles in viscoelastic fluids
• Theory of swimming filaments in viscoelastic media
• Active colloids in liquid crystals
• Enhanced active swimming in viscoelastic fluids
• Undulatory swimming in shear-thinning fluids: Experiments with C. elegans
• Liquid crystals in two dimensions: First-order phase transitions and nonuniversal critical behavior
• Locomotion and transport in a hexatic liquid crystal
• Liquid-crystal enabled electrophoresis: Scenarios for driving and reconfigurable assembling of colloids

Cited by in corpus (9)

• Inertial effects of self-propelled particles: from active Brownian to active Langevin motion
• An active approach to colloidal self-assembly
• Hydrodynamics defines the stable swimming direction of spherical squirmers in a nematic liquid crystal
• Emergence of Lévy Walks in Systems of Interacting Individuals
• Long-time anomalous swimmer diffusion in smectic liquid crystals
• Resonant diffusion of a gravitactic circle swimmer
• Inertial self-propelled particles in anisotropic environments
• Interstitial flows regulate collective cell migration heterogeneity through adhesion
• Dynamics of a simple model microswimmer in an anisotropic fluid: implications for alignment behavior and active transport in a nematic liquid crystal