There was some controvery on the internet recently about the explanation behind the so-called chain fountain effect. This is where a chain pouring out of a cup suddenly lifts up over the edge against gravity. I came across the idea watching a video by ElectroBoom

I found myself quite intrigued by the problem, especially since I felt like a simple computer simulation should be able to provide the answer. I set to making a Unity applet to test it. I've put this applet online for you to try and come to your own conclusions.


tl;dr I believe that Steve Mould is right in his levering off the bottom of the cup explanation. I did not think so at first, but working out the simulations has convinced me this is the case.

Fountain forces example

Here's hoping I can convince Steve or Mehdi to actually take a look!






So I did get a response from Steve! Here it is.

This is great!
Thanks for making it and sharing it with me. It's really fun to play with and it does seem to support my view which is nice.
Weirdly, when I've opened it just now the controls are missing from the left.

All the best


I haven't been able to find any technical problems. I was also hoping Steve might want to use the app in his argument but I assume he'd want to ask before doing that. In any case I am happy he found and liked it.