Fête de la science 2016: Cycle(s) de vie – Les rouages du monde

CNRS Nord – Pas de Calais
Gare Saint Sauveur, Lille – October 8 and 9, 2016

Stand Nage de micro-organismes: fluides visqueux et réversibilité temporelle
Stefano Berti and Enrico Calzavarini

Micro-organisms feel ordinary fluids like water the same way macroscopic organisms feel very viscous ones. This means that, at micron scales, swimming takes place in a low-Reynolds-number medium. In such environments, to achieve propulsion it is necessary to break time reversibility and this implies that not all sequences of elementary movements allow to swim. By realising simple macroscopic experiments in very viscous fluids we discuss some common swimming strategies adopted by micro-organisms. 

More details in our poster [pdf]

Our stand. On the left, a laminar demixer: Taylor-Couette setup (realised by Polytech’Lille’s student Florent Delmotte), filled with glycerol. On the right, containers filled with water (low viscosity) and glycerol (high viscosity) to test swimming efficiency of simple mechanical organisms (bathtub toys) at very different Reynolds numbers.
Enrico performing a simple experiment to illustrate the time reversibility of low-Reynolds-number fluids by mixing and demixing dye and glycerol in the Taylor-Couette system.
A movie showing the laminar demixer experiment.