Phoretic and hydrodynamic interactions of weakly-confined autophoretic particles

Abstract

Phoretic particles self-propel using self-generated physico-chemical gradients at their surface. Within a suspension, they interact hydrodynamically by setting the fluid around them into motion, and chemically by modifying the chemical background seen by their neighbours. While most phoretic systems evolve in confined environments due to buoyancy effects, most models focus on their interactions in unbounded flows. Here, we propose a first model for the interaction of phoretic particles in Hele-Shaw confinement and show that in this limit, hydrodynamic and phoretic interactions share not only the same scaling but also the same form, albeit in opposite directions. In essence, we show that phoretic interactions effectively reverse the sign of the interactions that would be obtained for swimmers interacting purely hydrodynamically. Yet, hydrodynamic interactions can not be neglected as they significantly impact the magnitude of the interactions. This model is then used to analyse the behaviour of a suspension. The suspension exhibits swirling and clustering collective modes dictated by the orientational interactions between particles, similar to hydrodynamic swimmers, but here governed by the surface properties of the phoretic particle; the reversal in the sign of the interaction tends to slow down the swimming motion of the particles.

15 pages, 4 figures, to appear in J. Chem. Phys

References in corpus (12)

• The hydrodynamics of swimming microorganisms
• Self-motile colloidal particles: from directed propulsion to random walk
• Designing phoretic micro- and nano-swimmers
• Hydrodynamics of self-propulsion near a boundary: predictions and accuracy of far-field approximations
• Self-propulsion of pure water droplets by spontaneous Marangoni stress driven motion
• 'Fuelled' motion: phoretic motility and collective behaviour of active colloids
• Dynamic clustering and chemotactic collapse of self-phoretic active particles
• Phoretic self-propulsion at finite Péclet numbers
• Self-assembly of Active Colloidal Molecules with Dynamic Function
• Chemotactic and hydrodynamic effects on collective dynamics of self-diffusiophoretic Janus motors
• Self-diffusiophoresis induced by fluid interfaces
• Active and driven hydrodynamic crystals

Cited by in corpus (1)

• Modeling chemo-hydrodynamic interactions of phoretic particles: a unified framework