Thomas Bickel- Some physical insight into Marangoni actuation

Laboratoire Ondes et Matière d’Aquitaine, Université de Bordeaux

The physical properties of the water-air interface are primarily controlled by its surface tension. The latter can be tuned by adding surfactant molecules, which preferentially adsorb at the interface and subsequently lower the surface tension. In the case where the concentration is not uniform, the resulting stresses induce a Marangoni flow in the bulk water phase. This effect can be exploited for the actuation of small particles by tuning locally the surfactant concentration. Yet, the variety of individual as well as collective dynamics that are observed experimentally remains largely unexplained. In this talk, I will present some recent theoretical predictions regarding the spreading dynamics of surfactant at the water-air interface. I will also discuss an ongoing project regarding the wake behind a self-propelled Marangoni surfer.