Asymmetric pattern formation in microswimmer suspensions induced by orienting fields

Abstract

This paper studies the influence of orienting external fields on pattern formation, particularly mesoscale turbulence, in microswimmer suspensions. To this end, we apply a hydrodynamic theory that can be derived from a microscopic microswimmer model [Phys. Rev. E 97, 022613 (2018)]. The theory combines a dynamic equation for the polar order parameter with a modified Stokes equation for the solvent flow. Here, we extend the model by including an external field that exerts an aligning torque on the swimmers (mimicking the situation in chemo-, photo-, magneto- or gravitaxis). Compared to the field-free case, the external field breaks the rotational symmetry of the vortex dynamics and leads instead to strongly asymmetric, traveling stripe patterns, as demonstrated by numerical solution and linear stability analysis. We further analyze the emerging structures using a reduced model which involves only an (effective) microswimmer velocity field. This model is significantly easier to handle analytically, but still preserves the main features of the asymmetric pattern formation. We observe an underlying transition between a square vortex lattice and a traveling stripe pattern. These structures can be well described in the framework of weakly nonlinear analysis, provided the strength of nonlinear advection is sufficiently weak.

References in corpus (38)

• Novel type of phase transition in a system of self-driven particles
• Active Particles in Complex and Crowded Environments
• The hydrodynamics of swimming microorganisms
• The Mechanics and Statistics of Active Matter
• The World of the Complex Ginzburg-Landau Equation
• Flocks, herds, and schools: A quantitative theory of flocking
• Physics of Microswimmers - Single Particle Motion and Collective Behavior
• Dynamical clustering and phase separation in suspensions of self-propelled colloidal particles
• Active Brownian Particles. From Individual to Collective Stochastic Dynamics
• Meso-scale turbulence in living fluids
• Hydrodynamic fluctuations and instabilities in ordered suspensions of self-propelled particles
• Fluid dynamics of bacterial turbulence
• Emergent behavior in active colloids
• Fluid Flows Created by Swimming Bacteria Drive Self-Organization in Confined Suspensions
• Collective motion and nonequilibrium cluster formation in colonies of gliding bacteria
• Active nematics on a substrate: giant number fluctuations and long-time tails
• Tuned, driven, and active soft matter
• Gravitaxis of asymmetric self-propelled colloidal particles
• Hydrodynamics of self-propelled hard rods
• Transport powered by bacterial turbulence
• Shearing active gels close to the isotropic-nematic transition
• Mesoscopic Turbulence and Local Order in Janus Particles Self-Propelling under an AC Electric Field
• Spontaneous flow states in active nematics: a unified picture
• Light control of the flow of phototactic microswimmer suspensions
• Minimal continuum theories of structure formation in dense active fluids
• Vortex arrays and meso-scale turbulence of self-propelled particles
• The role of correlations in the collective behaviour of microswimmer suspensions
• Derivation of a hydrodynamic theory for mesoscale dynamics in microswimmer suspensions
• Hydrodynamic length-scale selection and effective viscosity in microswimmer suspensions
• Turbulence and turbulent pattern formation in a minimal model for active fluids
• Pattern formation in active particle systems due to competing alignment interactions
• Vortex dynamics and Lagrangian statistics in a model for active turbulence
• Photofocusing: Light and flow of phototactic microswimmer suspension
• Particle-scale statistical theory for hydrodynamically induced polar ordering in microswimmer suspensions
• Non-linear rheology of active particle suspensions: Insights from an analytical approach
• Phase chaos in the anisotropic complex Ginzburg-Landau Equation
• Stratified spatiotemporal chaos in anisotropic reaction-diffusion systems
• Ordered and Disordered Defect Chaos

Cited by in corpus (12)

• Self-enhanced mobility enables vortex pattern formation in living matter
• Multi-species dynamical density functional theory for microswimmers: derivation, orientational ordering, trapping potentials, and shear cells
• Traveling band formation in feedback-driven colloids
• Ising-like critical behavior of vortex lattices in an active fluid
• Transport and phase separation of active Brownian particles in fluctuating environments
• Emergent pattern formation of active magnetic suspensions in an external field
• Pattern selection and the route to turbulence in incompressible polar active fluids
• Active dipolar spheroids in shear flow and transverse field: Population splitting, cross-stream migration and orientational pinning
• Vortex pattern stabilization in thin films resulting from shear thickening of active suspensions
• Geometric frustration and pairing order transition in confined bacterial vortices
• Rheologically tuned modes of collective transport in active viscoelastic films
• Optimal Turbulent Transport in Microswimmer Suspensions