Turbulent bubble rafts: self-organization and collective dynamics

We report on the collective dynamics of a turbulent bubble raft formed by a liquid jet impacting a bath of the same liquid. The jet-entrained bubbles self-organize into a floating raft with rich spatiotemporal dynamics. We track bubble trajectories and free surface wave statistics using synthetic Schlieren technique. Lagrangian tracking reveals wide-tailed accelerations, temporal correlations, and a flight-crash type behavior, reminiscent of inertial particle dynamics in hydrodynamic turbulence. These similarities are shown to arise from bubble bursts that trigger extreme raft reorganizations. Surface waves emitted by the burst-events correlate with bubble acceleration timescales, but distinct from the times scales of the collective raft motions. In contrast to classical static foams, bubble bursts deviate from power-law distributed avalanch statistics.