06/09/2019 – R. Jeanneret – Hydrodynamics of motile and sinking microorganisms
Séminaire IUSTI – 6 sept. 2019 – 11h salle 250
Hydrodynamics of motile and sinking microorganisms
Raphaël Jeanneret – LPS, Paris
In this talk I will present the results of two independent projects regarding the physics of phytoplankton. The first project deals with a very large class of non-motile phytoplankton called diatoms. Despite lacking motility we’ll see how these elongated unicellular organisms manage to encounter each other when sinking in quiescent fluids thanks to a hydrodynamically-driven density instability (instability well-studied at the IUSTI lab a few years back!). Our results pave the way for further investigating the yet poorly understood sexual reproduction that these globally-dominant organisms must occasionally go through to ensure the survival of the population. The second project is about the self-generated flow-fields that swimming microorganisms produce when swimming near surfaces. As opposed to previous theoretical predictions, we’ll show how the presence of no-slip boundaries enhances the diversity of microbial flow-fields compared to the bulk situation. Such results should have a large impact in e.g. our understanding of the emergence of collective behaviour of active suspensions in confined situations.