Expérimental et théorique
The green microalga Chlamydomonas Reinhardtii is a model microorganism, representative of uni- cellular and bi-flagellate eukaryotes. A dense solution of these microalgae spontaneously destabilises to form plumes. Surprisingly, currents generated in these convection cells are up to 10 times faster than the swimming speed of a single microalgae itself. The wavelength that naturally appears in this pattern is proportional to the depth of the solution, and the plumes are statistically steady. But, what happens when the thickness of the solution is not constant? How do convection cells interact? Is there any net propulsion of the pattern? The project aims at characterising and modelling the dynamics, through experimental macro- and microscopic observations. Mesoscopic scale will be accessed by numerical simulations, which will overall validate a model by comparison to experimental results.