title: Swimming droplets driven by a surface wave.
abstract: Self-propelling motion is ubiquitous for soft active objects such as crawling cells, active filaments, and liquid droplets moving on surfaces. Deformation and energy dissipation are required for self-propulsion of both living and non-living matter. From the perspective of physics, searching for universal laws of self-propelled motions in a dissipative environment is worthwhile, regardless of the objects' details. In this article, we propose a simple experimental system that demonstrates spontaneous migration of a droplet under uniform mechanical agitation. As we vary control parameters, spontaneous symmetry breaking occurs sequentially, and cascades of bifurcations of the motion arise. Equations describing deformable particles and hydrodynamic simulations successfully describe all of the observed motions. This system should enable us to improve our understanding of spontaneous motions of self-propelled objects.
authors.affiliation: Department of Physics, Graduate School of Science, Chiba University, Yayoi-cho, Chiba, 263-8522, JAPAN.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ebata
authors.affiliation: Department of Physics, Graduate School of Science, The University of Tokyo, Hongo, Tokyo 113-0033, JAPAN.
authors.forename: Masaki
authors.initials: M
authors.lastname: Sano