Hydrodynamic interactions in dense active suspensions: from polar order to dynamical clusters

Abstract

We study the role of hydrodynamic interactions in the collective behaviour of collections of microscopic active particles suspended in a fluid. We introduce a novel calculational framework that allows us to separate the different contributions to their collective dynamics from hydrodynamic interactions on different length scales. Hence we are able to systematically show that lubrication forces when the particles are very close to each other play as important a role as long-range hydrodynamic interactions in determining their many-body behaviour. We find that motility-induced phase separation is suppressed by near-field interactions, leading to open gel-like clusters rather than dense clusters. Interestingly, we find a globally polar ordered phase appears for neutral swimmers with no force dipole that is enhanced by near field lubrication forces in which the collision process rather than long-range interaction dominates the alignment mechanism.

7 pages, 4 figures

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Cited by in corpus (29)

• Computational models for active matter
• The physics of active polymers and filaments
• Clustering of microswimmers: Interplay of shape and hydrodynamics
• Which Interactions Dominate in Active Colloids?
• Active Colloidal Molecules
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• Simulating squirmers with multiparticle collision dynamics
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• Activity-controlled clogging and unclogging of micro-channels
• Particle-resolved lattice Boltzmann simulations of 3-dimensional active turbulence
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• Bodies in an Interacting Active Fluid: Far-Field Influence of a Single Body and Interaction Between Two Bodies
• Active particles with polar alignment in ring-shaped confinement
• Symmetric mixtures of pusher and puller microswimmers behave as noninteracting suspensions
• Shape dependent phoretic propulsion of slender active particles
• Collective motion in a sheet of microswimmers
• Gravity induced formation of spinners and polar order of spherical microswimmers on a surface
• Motility-induced clustering of active particles under soft confinement
• Collective behavior of squirmers in thin films
• Marangoni droplets of dextran in PEG solution and its motile change due to coil-globule transition of coexisting DNA
• Near and far-field hydrodynamic interaction of two chiral squirmers
• Long-wavelength instabilities in a system of interacting active particles
• Few-body hydrodynamic interactions probed by optical trap pulling experiment
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• Phase separation of self-propelled disks with ferromagnetic and nematic alignment
• Effect of Convection Rolls in Motility-Induced Phase Separation of Active Janus Particles