Velocity and size quantification of drops in single and collective bursting bubbles experiments

Mechanisms of droplet production from bursting bubbles have been extensively studied for single bubbles, but remain sparsely investigated in more complex collective settings. We discuss jet and film drop velocity-size relationships from physics-based mechanisms as a potential means to further differentiate between various mechanisms and correctly determine the drops origin. We report dynamical experiments of drop production by bursting bubbles in single and collective setups. In the collective bubbling experiment, subsurface quasimonodisperse bubbles are rising up to the surface where, depending on the surfactant concentration, they can either merge or assemble in rafts of monodisperse bubbles. Drop trajectories are recorded, analyzed, and shown to exhibit uniquely distinctive features for the different production mechanisms: centrifuge film drops are ejected sideways, and jet drops are ejected vertically. Different single-burst scalings are finally compared to the experimental size-velocity relationships, and reveal that drops coming from collective bubble bursting appear slower and more scattered than when coming from single bursting bubbles.

Automated summary

This study investigates the mechanisms and velocity-size relationships of droplet production from bursting bubbles in both single and collective settings. The experimental results show that droplets from collective bubble bursting have slower velocities and are more scattered compared to those from single bubble bursting.