Brazil Nuts [the dynamic behaviour of]

This is worth a look, if you ever wondered about ‘the Brazil Nut effect‘ : **LINK**

https://arstechnica.com/science/2021/04/cracking-the-case-new-study-sheds-more-light-on-the-brazil-nut-effect/

MichaelG.

MichaelG:

In my ignorance, I hadn't wondered; but I have added the phrase to my store of useful metaphors.

Well, this is NEWS - stones always rise to the surface of my garden (not a Brazil nut in sight). It doesn't matter how many times I remove them, more appear each season. It could be my neighbour - but I doubt that.

So next time I chat to some passing stranger, I can educate them and say that the stones follow the Brazil nut effect - that will impress them !!

Nearly spilt my tea!

David

The bit that impressed me was:

That's why the University of Manchester team turned to an advanced imaging technique, called time-lapse X-ray computer tomography, to follow the motion of all those jostling nuts as their container was repeatedly agitated.

What a great project: Getting to play with the toys !

MichaelG.

The stones in the garden might be due to frost heave, assuming that you are somewhere that gets reasonably hard frosts. I think the alternate freezing and thawing takes the place of shaking the can with the nuts in it. So still the same effect, just a different root cause. In some cold places the stones that come to the surface can form reasonably regular patterns like hexagons.

John

Hmmm - I suspect that lumps of lead of identical size and shape to Brazil nuts would not rise to ten surface so maybe the study is incomplete?

Other Brazil nut trivia is that they are quite highly radioactive - at least the shells are.

Don't they cover that:

" Scientists know that the size and shape of the nuts determines how much friction is produced, and their density also plays a role. "

I thought crushed walnut shells were preferred, but perhaps they're cheaper and the effect is similar...

It's logical enough when you think about it - a bunch of smaller rounded things that get under a larger rounded thing where they can't always escape sideways are more likely to reach a stable configuration than a bunch of smaller rounded things that get atop a larger rounded thing.

The best example of this I saw was at an factory that made adhesive tapes (masking tape, insulation tape). They had a new 5,000 Gallon storage tank installed in the factory yard and then re-laid tarmac over the top to re-instate the yard.

The tank rose up like a whale having 'floated' in the sand ballast and burst through the tarmac like a surfacing whale. I wish I'd had a camera.

I've noticed the same effect with dried fruit mixture. The banana slices are always on top however many times you try to get the mixed.

I think Steve's 5000 gallon tank was more to do with buoyancy rather than vibration.

Russell

It's at this point that I ponder why I've spent over 40 years working my nuts off.

Why wasn't I sat down in a university in California musing over the finer poins of nut

behaviour? Pop out the odd funding request , ponder the nuts a bit, all the while keeping

an eye on the surf reports, dirty work but I'd be dilligent.

.

Oh heck ... have they moved the University of Manchester over to California ?

MichaelG.

No but there are limits on where I'm prepared to do this ''work''