The Soul of a Bubble

Blowing bubbles is a childhood joy we can all relish as adults. But what happens inside these bubbles when we breathe life into them? In this experiment, we explore the internal dynamics of a bubble. We achieve this by blowing air seeded with olive oil droplets through a soap-coated nozzle to form a bubble and using a laser sheet to illuminate the flow inside. The result is a captivating vortical motion where the incoming air jet meets the bubble's surface. This phenomenon resembles the interaction of a laminar air jet (Re ~ 200) with an expanding concave surface.