Drop impact on a sessile soap bubble

Abstract

The dynamics of a water droplet impacting onto a soap bubble sitting on a solid substrate was experimentally investigated using a high-speed camera. At low impact velocities, the droplet bounced on the soap bubble. Varying the size of the soap bubble, we discovered two regimes at high impact velocities. For a soap bubble larger than a critical dimensionless height of 3.18, the water droplet passed through the soap film, while the soap bubble burst as the bubble height was less than the critical value. Theoretical models were proposed for the critical impact velocities needed to reach these two regimes, with their intersection correctly capturing the critical bubble height separating them. Two mechanisms for the bursting of the soap bubble were identified depending on the location where the bursting started, either from the center below the impacting droplet or from the periphery of the soap film. Moreover, the bursting of the soap bubble could be suppressed by replacing the solid substrate below the bubble with a tube.