I discovered an unusual bubble structure which is unexpectedly very stable. To make it, you blow a hemispherical bubble in a pan of soap water using a straw. Then, while still blowing through the straw, withdraw the straw from the bubble. Under the right conditions, a sausage-like corrugated tube of soap film will form between the straw and the bubble. The tube collapses when you stop blowing. Without airflow, it can be proved that long cylindrical bubbles are unstable. As far as I know, nobody has studied bubble stability with airflow. <br>
I'd like to put together a contraption to blow bubbles and study them. Here's what I think I might need:
* An aquarium or fish tank to hold the setup
* An aquarium pump & rubber hose to provide airflow
* A way of measuring the airflow rate
* Some adjustable structure like 80-20 rails to mount components
* A digital camera to capture images
My current hypothesis is that the bulges in the bubble tube contain ring vortexes. This would be easy to confirm by examining the flow pattern on the surface of the bubble. I'd also like to see what the critical airflow rate is, and how the shape changes with flow rate.