Real world sphere packing

Hi All,

Sorry for sharing this here as it's not a question, but I thought this might be interesting...

As soon as I saw this picture I remembered the circle (and sphere) packing exercises done here.

Look at the amazing patterns generated.

And if you don't know what this is, it's a picture of millions of plastic balls, being dumped over a water reservoir in LA to reduce evaporation. You can read about it: here and here.

Regards,

Omar

Replies to This Discussion

Permalink Reply by Nik Willmore on August 16, 2015 at 8:25am

As a chemist I was grabbed by it too when I saw it since it looked so much like atomic force microscope scans of microcrystalline domains.

So far, Kangaroo and Kangaroo2 are too good at equilibrating such packing of hard balls to have them lock together into stable subdomains in which "you can't get there from here" after they are jammed together.

Permalink Reply by Kim hauer on August 16, 2015 at 9:48am

It would be interesting to do a simulation. I one might be able to do this with Houdini, if one had too much time of their hands :)

http://www.digitaltutors.com/tutorial/2116-Introduction-to-Dynamic-...

Permalink Reply by Daniel Piker on August 16, 2015 at 12:12pm

Nice picture.

Geometrical frustration and granular jamming are really fascinating phenomena.

I had a quick go at simulating something in Kangaroo (I'll post a video too once it finishes uploading):

Permalink Reply by Nik Willmore on August 16, 2015 at 6:13pm

Are you saving the script secrets for some upcoming book? What force locks them together without the usual crazy kinetics that bounces around way too much all the time?

Here you also have quite an artifact of how the angle of the funnel will not allow the spheres to form a lattice while still touching the funnel under strong gravity. That's not like free floating atoms or balls in a huge reservoir. You cheated ;-).

Permalink Reply by Daniel Piker on August 17, 2015 at 9:51am

The spheres are better behaved here because of a recent improvement I made in the SphereCollide goal (it will be in the next release).

While the funnel walls and gravity are obviously different from balls floating on water, I'm not sure the basic mechanism causing regions of regularity with global disorder is so different - groups of spheres get pushed into regions of close-packed arrangements with slightly different angles, and resistance from the surroundings (funnel walls or the inertia of the expanding mass of balls) prevents these regions from rotating to align perfectly with each other. Though perhaps there is some other phenomenon at play here too.

You can see the patterns forming here:

https://www.youtube.com/watch?v=lqhF2JpZBVs

I wonder if filling it more slowly would result in larger grain size, like crystallites in metals.

Permalink Reply by Nik Willmore on August 17, 2015 at 1:57pm

Semiconductors like silicon are conductive enough in impure state to be melted with induction coils, into little black balls called atoms:

But they are smart spheres with preferred valence of four.

Permalink Reply by Daniel Piker on August 16, 2015 at 1:20pm

Permalink Reply by taz on August 17, 2015 at 12:18pm

On a semi-related note this will be happening soon (this month?) in LA. Not sure how dense the lake will be packed with multi-diameter spheres, but the visualization obviously looks a bit dubious as there is no grouping behavior.

Permalink Reply by taz on August 18, 2015 at 5:18pm

Goes up on Saturday...

Los Angeles, California (PRWEB) August 18, 2015

WHO: Esteemed press and the Los Angeles community will witness Portraits of Hope bring their largest civic art project to life.

WHAT: Spheres painted by members of the Los Angeles community will be launched into the lake at MacArthur Park to visually enhance and revitalize the iconic landmark. By rallying members of the public to work together to complete the exhibition, a sense of community has been re-installed in the heart of Los Angeles. The brightly colored floating artwork hopes to bring locals back to MacArthur Park to continue to strengthen the bond of their community. Following the exhibition, the historic spheres will be donated to continue to bring color and beauty to surrounding areas within social services such as hospitals, schools and women’s shelters.

WHEN: Saturday, August 22 , 2015; 12PM - 8PM (from 12:00pm-12:30pm, there will be a pause in installation to offer a first look to press and media)

WHERE: MacArthur Park, 2230 W 6th St, Los Angeles, CA 90057

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