Berlin 2018 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 37: Active Matter (joint session BP/CPP/DY)
BP 37.2: Vortrag
Freitag, 16. März 2018, 09:45–10:00, H 1058
Statistical physics and hydrodynamics of passive/active mixtures — •Raphaël Jeanneret1, Arnold Mathijssen2, and Marco Polin3 — 1IMEDEA-UIB, Esporles, Spain — 2Stanford University, Stanford, US — 3Warwick University, Coventry, UK
In this talk I will present a series of experimental and theoretical results regarding the dynamics of passive particles in liquid bath of active ones. The active particles act here, via the flows they generate, as localized and erratic sources of momentum for the passive beads leading to non-trivial dynamics. Beyond their exciting features for the physicist, active/passive systems are worth studying quantitatively for applications as diverse as the transport of passive entities in cells, biogenic mixing (i.e. mixing of the ocean by living creatures), virus infection, cargo transport (e.g. drug delivery) or self-assembly (e.g. via motility-induced phase separation). The model system I consider is composed of the motile micro-alga Chlamydomonas reinhardtii, a model organism at numerous levels, and polystyrene beads. I will first show that the effective diffusion of micron-sized beads embedded in homogeneous suspensions of algae is greatly enhanced compared to their thermal counterpart. I will then demonstrate how this coarse-grained dynamics can be understood from the near-field hydrodynamics of the swimming organisms via hydrodynamical entrainment events. Finally I will talk about recent results regarding systems of weakly Brownian colloids in spatially heterogeneous suspensions of algae and show how our findings can be used to induce the spontaneous demixing of the two kinds of particles.