Understanding the Dynamics of Soap Bubble Pinch-off Courtney Cromartie, Daniel Lathrop, Sonali Shukla

Inspiration for Project Soap Film Topology Talk with Keith Moffatt Unfolding a mobius strip Singularities in catenoids

What About a Blown Bubble?

Stages of Pinch-off

Apparatus Design

Experimental Set-up High-speed video camera 2,000 fps, 140 x 160 pixel frame Pressurized Air Designed a valve system to control the delivery of air to the nozzle External Triggering Device Provided precision control timing of camera and air burst

Optimizing Bubble Dynamics Soap Solution 60 ml distilled water, 10 ml Dawn dishwashing liquid, 3 ml glycerol Careful balance of pressure and air burst length to produce: Symmetric Single-pinch off events Consistently

Edge Tracing & Image Analysis z - z0 = (internal wall location) – (location of internal collapse)

Controlling Forces Proposed that surface tension and kinetic energy of fluid control the process of pinch- off Dimensional Analysis of force equality uncovers a 2/3’s power law between length and time.

Preliminary Results from 10 Events Later Stages of Collapse Early Stages of Collapse

Closing Thoughts Kinetic Energy and Surface Tension likely play a role in the early stages of pinch-off A camera with a higher frame rate and better resolution would yield more definitive results close to pinch-off

Special Thanks To: Daniel Lathrop & Sonali Shukla UMD TREND Program National Science Foundation