Collective behaviour in suspensions of swimming micro-organisms

Tim Pedley, DAMTP Cambridge

Suspensions of swimming micro-organisms exhibit a rich variety of collective behaviour, such as the bioconvection patterns seen for suspensions of upswimming cells that are denser than their surroundings, or the time-varying coherent structures seen in dense suspensions of swimming bacteria. Here we investigate the fluid dynamic mechanisms underlying these patterns, by means of (1) a continuum model for dilute suspensions, (2) hydrodynamic interactions between pairs of model micro-organisms, and (3) simulations and models for non-dilute suspensions. The talk will conclude with observations of ‘dancing’ algae, and other recent work if time permits.