Active polar fluid flow in finite droplets

Abstract

We present a continuum level analytical model of a droplet of active contractile fluid consisting of filaments and motors. We calculate the steady state flows that result from a splayed polarisation of the filaments. We account for the interaction with an arbitrary external medium by imposing a viscous friction at the fixed droplet boundary. We then show that the droplet has non-zero force dipole and quadrupole moments, the latter of which is essential for self-propelled motion of the droplet at low Reynolds' number. Therefore, this calculation describes a simple mechanism for the motility of a droplet of active contractile fluid embedded in a 3D environment, which is relevant to cell migration in confinement (for example, embedded within a gel or tissue). Our analytical results predict how the system depends on various parameters such as the effective friction coefficient, the phenomenological activity parameter and the splay of the imposed polarisation.

9 pages, 5 figures + 4 appendices (15 pages total)

References in corpus (5)

• Spontaneous motion in hierarchically assembled active matter
• Pushing off the walls: a mechanism of cell motility in confinement
• Spontaneous Circulation of Confined Active Suspensions
• Generic phase diagram of active polar films
• Spontaneous motion and deformation of a self-propelled droplet

Cited by in corpus (15)

• Nonequilibrium Physics in Biology
• Spontaneous division and motility in active nematic droplets
• Periodic migration in a physical model of cells on micropatterns
• A mechanism for cell motility by active polar gels
• Vortex formation and dynamics of defects in shells of active nematics
• Motility of active fluid drops on surfaces
• Multiphase field models for collective cell migration
• Instabilities, motion and deformation of active fluid droplets
• Thin-Film Modelling of Resting and Moving Active Droplets
• Fingering Instability of Active Nematic Droplets
• The crucial role of adhesion in the transmigration of active droplets through interstitial orifices
• How many ways a cell can move: the modes of self-propulsion of an active drop
• Anchoring-driven spontaneous rotations in active gel droplets
• Shapes and dynamic regimes of a polar active fluid droplet under confinement
• Self-propulsion of an active polar drop