Instabilities, motion and deformation of active fluid droplets

Abstract

We consider two minimal models of active fluid droplets that exhibit complex dynamics including steady motion, deformation, rotation and oscillating motion. First we consider a droplet with a concentration of active contractile matter adsorbed to its boundary. We analytically predict activity driven instabilities in the concentration profile, and compare them to the dynamics we find from simulations. Secondly, we consider a droplet of active polar fluid of constant concentration. In this system we predict, motion and deformation of the droplets in certain activity ranges due to instabilities in the polarisation field. Both these systems show spontaneous transitions to motility and deformation which resemble dynamics of the cell cytoskeleton in animal cells.

9 + 6 SI pages, 6 figures

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• Tractionless Self-Propulsion of Active Drops
• Fingering Instability of Active Nematic Droplets
• Self-consistent sharp interface theory of active condensate dynamics
• How many ways a cell can move: the modes of self-propulsion of an active drop
• Anchoring-driven spontaneous rotations in active gel droplets
• Stability of the interface of an isotropic active fluid
• Immersed Boundary Simulations of Active Fluid Droplets
• Self-organization and shape change by active polarization in nematic droplets
• A computational model of self-organized shape dynamics of active surfaces in fluids
• What is active wetting?