Physicists Turn The Cheerio Effect Inside Out
If you’ve ever managed to try Cheerios, you may have noticed how those last few Cheerios in the cereal bowl seem to cluster together in the centre and along the edges. It’s called the “Cheerios effect.” Now an international team of physicists has discovered a reverse Cheerios effect. They described their results in a new paper in the Proceedings of the National Academy of Sciences.
The Cheerios effect may not be an especially exotic phenomenon — we also see it in pollen floating atop a pond, and the foamy heads of beer — but the actual physical mechanisms at work weren’t clearly outlined until a 2005 paper in the American Journal of Physics. The culprits: buoyancy, surface tension, and something called the “meniscus effect.”
Buoyancy is what determines whether something will sink or float, while surface tension is a property arising from water molecules pulling on one another in a dance of mutual attraction. The liquids
The original Cheerios effect led to advanced materials and insight into how galaxies collapse via gravity. Its inverse also has lots of potential applications, according to co-author Lorenzo Botto of Queen Mary University of London. “[T]he physical phenomena we have highlighted in this paper suggest ways to design surfaces that prevent fogging or control heat transfer,” he said. This would make it possible to “create car windows that are always transparent despite high humidity or surfaces that improve heat management in conditioners or boilers.”
[Proceedings of the National Academy of Sciences]