The Strange World of Low Reynolds Numbers: How to Move at the Micron Scale.

Holger Stark, TU Berlin

At the micron scale, inertia is completely negligible in an aqueous environment. This means that microorganisms swimming in water had to invent their own strategies to move forward.

I will explain these strategies at a few examples and demonstrate that the physics at low Reynolds number allows for interesting non-linear dynamics such as synchronization and Hopf bifurcation.

In particular, I will talk about a biomimetic flagellum or cilium. This is a long elastic filament that has been used to construct an artificial swimmer or to transport fluid. I will then demonstrate how an array of cilia synchronize into metachronal waves and finally introduce how we model bacterial locomotion. Bacteria move forward with the help of a rotating bundel of helical filaments. Modeling these filaments and their actuation by a rotary motor offers interesting new insights into the problem.