Numerical Simulation of Chain Fountain ('Mould effect')

This video shows a simulation of a chain fountain where the chain is modeled as a series of boxes connected by hinges with angle limits. It demonstrates that smaller angle limits increase the magnitude of the effect dramatically. I was unable to reproduce the effect without the use of angle limits.

Steve Mould's explanation video:

[monotonespectrum]

Very cool, I just watched Steve Mould's video and was thinking of simulating this myself! Glad to see this works in 2D

[typha]

Two things in particular that I notice about this that I find interesting:
-One is that the chain is always a lot wigglier on the left side of the peak, this is something I have observed in experimental results, but feel like is often missing or lacking in other people's simulations.
-The second is that chains with more limited range of motion fall faster on average... which is a quirky result. :)

nice job.

[wild_lee_coyote]

If you watch closely you see the waves going back and forth adding up pushing the chain higher each time it goes back and forth. The higher angles just don’t add as much on each switch. So it’s not so much pushing off the bottom like in the paper mentioned in the other video, but pushing up on every direction change that adds a half circle to the stack.

[hankdewit]

Can you increase the sliding friction so that the chain with the large angle freedom can experience more of the oscillating effect as it picks up the chain. The low angle freedom chains have large oscillations which travel up the chain and may be part of the story. You might also try a bottle container to limit the oscillations that leave the surface. Nice work.

[franklinedwardham]

very nice job. Are you able to remove the angle constraint from all these simulations after the chain leaves the lower part of the container? That would isolate the lifting force effect when the chain leaves the from the inertial/certifugal effects at the top of the fountain.

[zaphodbeeblebrox]

It's easier to understand by imagining a weight on the lever near the pivot. The angular momentum makes the end of the lever go faster than gravity.
The chain fountain is the same thing BUT the "Mould effect" is not the whole story. When you lift up on a chain link(lever) you ALSO induce precession that causes the link to twist or the bead on the chain to spin. The spinning beads carry energy to the top of the arc where they resist turning around (like a gyroscope). They resist the pull of the falling chains.
13:10 in this video you can clearly see the chain twisting on the slack side. Each link(lever) starts to turn as it get accelerated from a standstill

[rinaw]

Very impressive. Is this a commercially available physics engine software that was used/adapted? OR your own creation? Is it an open source project?

[Sooty_Grandad]

It takes only 7 balls of the ball chain to form a full circle. That means 6 links between the 7 balls. That is 60 degree's angle limit. Guess that blows the mould effect out of the water. It is inertia that causes the chain fountain, not some trumped up !mould! effect. Simulations are only as good as those inputting the data parameters.

[typha]

I'm wondering:
A) if you could upload the video of that simulation to youtube as well as it's own video, and
B) did that simulation include a friction force between the chain an the rod?

ps. Just as a side note, I have also suggested that a having the chains draped over a "comb" or "rake" sort of situation should also remove the rod-lever effect that Mehdi describes, isolating the pulley effect that Steve described.