Here be the fruits of my critical-fall in soap films investigation. Apologies for my delay in adding these final images, there are just soo many neat Photographs! From these images I present ten in the gallery below. These patterns form as a thin soap film – think blowing bubbles at a wedding – gets thinner…
I have here drawn a thin film up out of a reservoir of soap solution to create a vertical rectangular film. As the film gets thinner, the white light used to illuminate it experiences destructive interference that causes the beautiful spectrum of colors. Various surface tension and buoyancy forces create specific swirling patterns of rising and falling fluid flow. I’ll say more below.
an image in gallery below
- to open a slider menu, these images really need to be seen
- to appreciate the details. Enjoy!
The primary phenomenon of this investigation is critical-fall, which can be described by the branching and ballooning patterns. This results from the stability of a very thin portion of the film, known as the ‘black film’, because it is transparent and appears black. This black film grows and ‘eats away’ at the thicker film, eventually replacing it. But first it creates the complex patterns of drops, balloons, lakes, rivers, trees… choose your metaphor.
Additionally there are some neat examples of marginal regeneration and Marangoni convection. The triangle image shows the creation of a vortex – whirlpool! – using a LEGO tire spun by a motor. I hope to expand on that experiment someday.
I hope you enjoy, and I would be happy to answer any questions about my setup, and investigation and research of soap films, including the various physics and flow principles involved. I wrote a little paper about criticall fall (direct link) which you can read at the University of Colorado Flow Vis Website. Further, if you have information to share about critical-fall I would love to hear about it!