  Surfactant distribution heterogeneities at a fluid/fluid interface trigger
the Marangoni effect, i.e. a bulk flow due to a surface tension gradient. The
influence of surfactant solubility in the bulk on these flows remains
incompletely characterized. Here we study Marangoni flows sustained by
injection of hydrosoluble surfactants at the air/water interface. We show that
the flow extent increases with a decrease of the critical micelle
concentration, i.e. the concentration at which these surfactants self-assemble
in water. We document the universality of the surface velocity field and
predict scaling laws based on hydrodynamics and surfactant physicochemistry
that capture the flow features.
