Role of Marangoni forces in the velocity of symmetric interfacial swimmers

Interfacial swimmers self-propel by maintaining a surface tension gradient around them, often through the release of a surfactant. The symmetry-breaking mechanism underlying motion of symmetric swimmers is qualitatively understood but the role of Marangoni flows in self-propulsion has never been elucidated. We address this question by numerical methods, which can handle the complex couplings at play. We find that Marangoni flows play a key role near the onset of swimming but have only a modest influence at large velocities. We discuss the generality of those conclusions and their relation to experiments.