Lattice Boltzmann simulations of active gels: spontaneously rotating droplets and self-assembled nonequilibrium cholesterics

We use the hydrodynamic theory of active gels to study the dynamics of a binary system, where a droplet of active gel is embedded into an isotropic and Newtonian, aqueous, solvent. Previous work has shown that such droplets can become self-motile if the magnitude of the active stress is large enough. In the presented work, we consider the effects of an imposed (e.g. thermodynamic) anchoring of the particle orientation to the droplet surface. In such conditions, we observe a non-equilibrium transition to spontaneously rotating states, which are powered by elastic deformations and involve a change in the droplet shape. I will characterise the mechanism underlying these rotations and how it depends on the interplay between activity, surface tension and surface anchoring.

I will also show some results for the extension of the active force dipole model to the inclusion of active torque dipoles. The interest of this study lies in the fact that many biomolecules exhibit chiral asymmetry, generating active chiral processes and torque dipoles. Our results for bulk quasi-1D and 2D show a spontaneous break of chiral symmetry, leading to a self-assembled chiral phase.