On the 15th of March, Matthieu Martin will defend his PhD entitled "Study of the clustering and dispersion effects in a suspension of microalgae: influence of hydrodynamic interactions on the dynamics of the suspension".
This PhD project started in 2014 was supervised by Salima Rafaï and Philippe Peyla at the LIPhy.
The defense will take place at 2 pm in the conference room at LIPhy.
The subject of this thesis is part of the study of the active matter. These systems are composed of "active particles" capable of organizing themselves spontaneously (phase transition), and autonomously (without application of an external field), thus creating complex dynamics such as dynamical phase transition, synchronization, instabilities etc ...Numerous studies tend to show the important role of interactions between active particles in the emergence of these dynamics. We have addressed these issues through the study of a suspension of microalgae Chlamydomonas reinhardtii. It is a model system of micro-swimmer commonly used for the study of active suspensions. We studied in particular a phenomenon of spontaneous migration of the suspension, allowing to concentrate micro-algae thanks to a light source. We then studied the dispersal process of a concentrated bloom of microalgae. In particular, we have highlighted the role of hydrodynamic interactions between micro-algae in this dispersion dynamics.