Regensburg 2016 – scientific programme

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BP: Fachverband Biologische Physik

BP 30: Microswimmers I (Joint Session with DY)

BP 30.6: Talk

Tuesday, March 8, 2016, 11:15–11:30, H47

Dimensionality matters in the collective behaviour of active emulsions — •Corinna Maaß, Carsten Krüger, and Stephan Herminghaus — MPI for Dynamics and Self-Organization, 37077 Göttingen, Germany

Microswimmer systems like plankton constitute an important part of our ecosystem. The description of such systems is complex, as it involves large numbers of agents, long range hydrodynamic interactions and nontrivial boundary conditions like turbulent flows and complex interfaces. They exhibit rich and sometimes puzzling behaviour like the high species diversity referred to in the Plankton Paradox, or self organised bioconvection of gravitactic bacteria. This complexity makes them hard to treat analytically and numerically. Large scale simulations usually have dimensional restrictions or exclude hydrodynamic interactions, which has to be considered in comparisons with natural systems. Simple, tunable artificial swimmer systems can help bridging this gap.

Our experimental system consists of an active emulsion of self propelling liquid crystal droplets under variable microfluidic confinement and with tunable buoyancy. While changing the system's geometry from a quasi 2D confinement to a full 3D bulk reservoir, we observe a pronounced transition from only transient local aggregation over line formation to a large scale clustering phase stabilised by self-generated convection patterns. We studied this clustering behaviour in more detail with respect to reservoir height and buoyancy.