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Capillary surfers
Active systems have recently attracted considerable interest for the possibility of extending statistical mechanics to incorporate non-equilibrium phenomena, as their constituents locally consume energy in order to move or exert forces on each other. There has been extensive work on dissipation and inertia-dominated active systems (e.g. bacterial suspensions and fish schools, respectively), but our understanding of the intermediate regime between these two extremes is currently limited.
We introduce capillary surfers, a new fluid-mediated active system that has the potential to bridge the gap between dissipation- and inertia-dominated regimes. Surfers are wave-driven particles that self-propel and interact on a vibrating fluid interface via an extended field of surface waves. A surfer’s speed and interaction with its environment can be tuned broadly through the particle, fluid, and vibration parameters. The wave nature of interactions among surfers allows for multistability of interaction modes and promises a number of novel collective behaviors.