Hydrodynamic length-scale selection and effective viscosity in microswimmer suspensions

Abstract

A universal characteristic of mesoscale turbulence in active suspensions is the emergence of a typical vortex length scale, distinctly different from the scale-invariance of turbulent high-Reynolds number flows. Collective length-scale selection has been observed in bacterial fluids, endothelial tissue and active colloides, yet the physical origins of this phenomenon remain elusive. Here, we systematically derive an effective fourth-order field theory from a generic microscopic model that allows us to predict the typical vortex size in microswimmer suspensions. Building on a self-consistent closure condition, the derivation shows that the vortex length scale is determined by the competition between local alignment forces and intermediate-range hydrodynamic interactions. Vortex structures found in simulations of the theory agree with recent measurements in Bacillus subtilis suspensions. Moreover, our approach correctly predicts an effective viscosity enhancement (reduction), as reported experimentally for puller (pusher) microorganisms.

5 pages, 4 figures

References in corpus (9)

• Spontaneous motion in hierarchically assembled active matter
• Meso-scale turbulence in living fluids
• Fluid dynamics and noise in bacterial cell-cell and cell-surface scattering
• Non-equilibrium clustering of self-propelled rods
• Fluid Flows Created by Swimming Bacteria Drive Self-Organization in Confined Suspensions
• Hydrodynamics of self-propelled hard rods
• Mesoscopic Turbulence and Local Order in Janus Particles Self-Propelling under an AC Electric Field
• Minimal continuum theories of structure formation in dense active fluids
• Effective Viscosity of Dilute Bacterial Suspensions: A Two-Dimensional Model

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• Which Interactions Dominate in Active Colloids?
• Derivation of a hydrodynamic theory for mesoscale dynamics in microswimmer suspensions
• Clustering and phase separation of circle swimmers dispersed in a monolayer
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• Actively crosslinked microtubule networks: mechanics, dynamics and filament sliding
• Anomalous diffusion and Lévy walks distinguish active from inertial turbulence
• Swimming trajectories of a three-sphere microswimmer near a wall
• Analytical approach to chiral active systems: suppressed phase separation of interacting Brownian circle swimmers
• State diagram of a three-sphere microswimmer in a channel
• Self-enhanced mobility enables vortex pattern formation in living matter
• Dynamical density functional theory for circle swimmers
• Emergence and melting of active vortex crystals
• Towards an analytical description of active microswimmers in clean and in surfactant-covered drops
• Multi-species dynamical density functional theory for microswimmers: derivation, orientational ordering, trapping potentials, and shear cells
• Particle-scale statistical theory for hydrodynamically induced polar ordering in microswimmer suspensions
• Motility-Induced Clustering and Meso-Scale Turbulence in Active Polar Fluids
• Frequency-dependent higher-order Stokes singularities near a planar elastic boundary: implications for the hydrodynamics of an active microswimmer near an elastic interface
• Active Flows on Curved Surfaces
• Ising-like critical behavior of vortex lattices in an active fluid
• Delayed feedback control of active particles: a controlled journey towards the destination
• Memory-based mediated interactions between rigid particulate inclusions in viscoelastic environments
• Giant vortex dynamics in confined active turbulence
• Asymmetric pattern formation in microswimmer suspensions induced by orienting fields
• Swimming suppresses correlations in dilute suspensions of pusher microorganisms
• Nonstationary models for liquid crystals: A fresh mathematical perspective
• Dynamics of a microswimmer-microplatelet composite
• Time scales of inertial motion in the collective dynamics of underdamped active phase field crystal systems
• Mean field approach of dynamical pattern formation in underdamped active matter with short-ranged alignment and distant anti-alignment interactions
• Stochastic motion under nonlinear friction representing shear thinning
• Turbulence-induced clustering in compressible active fluids
• Enhanced velocity fluctuations in interacting swimmer suspensions
• Pattern selection and the route to turbulence in incompressible polar active fluids
• Statistics for an object actively driven by spontaneous symmetry breaking into reversible directions
• Flocking turbulence of microswimmers in confined domains
• Self-sustained patchy turbulence in shear-thinning active fluids
• Oscillating edge current in polar active fluid
• Optimal Turbulent Transport in Microswimmer Suspensions
• Dynamics of a simple model microswimmer in an anisotropic fluid: implications for alignment behavior and active transport in a nematic liquid crystal
• Stable and unstable flow regimes for active fluids in the periodic setting