Active matter refers to collective, ordered states of matter in ensembles of particles with intrinsic motion and alignment interactions. Examples span biological systems, like bird flocks and bacterial swarms, down to cellular tissues and subcellular systems, e.g. cytoskeletal filaments. These active systems exhibit large-scale orientational ordering in analogy with liquid crystals of different discrete rotational symmetries (polar, nematic, triatic..). At sufficiently high activity, the orientational order is locally punctuated by the spontaneous nucleation of topological defects which induce long-range elastic distortions and persistent flows.
Spontaneous flows in active liquid crystals
We study the spontaneous active flows induced by topological defects in thin active films with nematic or polar order. Using hydrodynamic models of active liquid crystals, we investigate the effect of incompressibility constraint, the role of hydrodynamic screening length and inhomogeneous activity on the flow profiles and defect dynamics.
We develop a discrete model for aggregates of cells interacting through their cell polarities study the interplay between flow, topology and geometry during the early tissue morphogenetic processes.
