Granular Dynamics - Sixty Symbols

Shaking grains and interesting physics.
With James Clewett
Visit our website at www.sixtysymbols.com/
We're on Facebook at / sixtysymbols
And Twitter at #!/periodicvideos

[@UDubFootballFan]

I don't understand half of what this channel is talking about but it's fascinating. I love learning about these complex sciences.

[@PandaBasher]

I'm going to Nottingham to study Physics this September, can't wait! These videos just make me more excited, keep them coming :)

[@avi-brown]

What are you doing now??

[@desromic]

Stunning effect! The pressure drop still blows my mind.

[@PhailingMath]

The paper and authors shown briefly at the end is "Liquid-Gas Phase Separation in Confined Vibrated Dry Granular Matter," by Roeller et al. It would be helpful to include this information in the description.

[@EmdrGreg]

This is great stuff. And the smiley face at 9:39 is a bonus.

[@Mojosbigstick]

This series continues to blow my tiny mind! Thank you for making them. I think I'll bring up granular dynamics in my job interview today.

[@bjjolley]

One of the best channels anywhere on the Internet. Consistently jaw-dropping, accessible science.

[@Acid113377]

This is one of the, if not, THE best video on sixtysymbols, thank you very much Brady!

[@gaeel330]

I really enjoyed this video, I love seeing what researchers are working on. It's interesting to watch all these little steps in various fields, each pushing human understanding just a notch further.

[@iagolima6122]

I really really love this channel. Keep up the amazing job!

[@G33RTJEH]

What part does Aero-drag play in this test? If you get the grains to resonate together, the air-resistance would probably help the formation of the clusters around the borders, where the air is to be expected to follow the surrounding walls too. Can you try the same experiment in a vacuum? Also: While the frequency was stable, the amplitude was altered, but the allowed "waivelenght" for the particles is limited. This looks like an Amplitude modulation instead of a frequency modulation.

[@robobrain10000]

Can you guys make more videos on a constant basis. We really appreciate the effort you guys put into filming them.

[@SolarWebsite]

Most of these videos are interesting and I always enjoy watching them, but this is the most interesting one I've seen in a while. What an odd and counterintuitive effects nature sometimes performs for us. Fascinating!

[@DaveAtLeeds]

Yet another top video, Brady!

[@Superminyme]

Wow, that's actually quite amazing. Just makes me think about what else is out there that we haven't even tapped in to yet.

[@marsCubed]

Totally interesting research, thanks sixtysymbols.

[@mothercromby]

I'm glad I found this because I have to admit I didn't quite understand what you meant when you explained this to me on the open day. I think I know what it's about now :)

[@errmoc5682]

I love the way the sand looks when he first turned it on. it's kind of seeing snow on the television. I find it mesmerizing

[@ZardoDhieldor]

I like the fact, that you programm a simulation where you know the whole code and however something unknown happens! :)

[@brothermaleuspraetor9505]

Very inspiring.. :Lots of ideas flowing now.. thanks :)

[@TheZooman22]

Dan J It seems like it could be connected to Cymatics .

[@Guterjuls]

another great video! Thank you sixtysymbols :)

[@toast_recon]

That's a very clever theory to fit the observation, but remember he also talked about how the effect still appears in a computer simulation, where they would not have included air as a factor (and if they had, they would have found that to be the reason for the effect). The first precaution they would take with this sort of thing would be to ensure that the effect exists in a perfect model of the grains rather than an imperfect experiment.

[@cheeseontoast14]

i love how he got so happy with the boxes, awesome!

[@msungo777]

Yes, but in the video, they are not mentioning vacuum anywhere, the simulation is mentioned as confirming that the effect works with ideally level and flat surface, not that it works without air. For all we know from the video, the simulation might have included atmosphere as well.

[@Wtf634]

@Azyashi Here's what I think happened. Remember the ideal gas law? PV=nRT or PV=mRT depending on your units. When the granules were in random motion, all the energy input from the vibrator thing = energy lost. When the granules started bouncing coherently, the "temperature" of the granules spiked up and so did the pressure. Since he said that collecting at one point will lower the pressure/temperature, all the granules started collecting there and eventually it evened out again. Unsure though.

[@bassman2914]

If I'm not mistaken, in one of these videos about granular dynamics, it was said that this doesn't seem to be explained by "normal" laws of physics. If however a computer simulation (which presumably uses normal physics) shows the same results, then it must be explainable by our currently understood laws of physics, even if we don't know how. When you think about it, the fact we can program a simulation and have things happen that we can't explain, is kind of funny, and neat.

[@TheScabbage]

0:30 His enthusiasm for his boxes is reminiscent of the Malta potatoes video.

[@njimko23]

@Ichijojichan I'm guessing the particles resonate between the top and bottom surfaces at a certain frequency and so they have a lot of kinetic energy, but if they get too crowded and start bumping into each other the resonance stops because the particles are hitting the top and bottom at random times during the up/down cycle.

[@HiAdrian]

"Hey, it's the Tetris Guy!" the audience shouts. This was very well explained imo, nice work.

[@FatLingon]

I submit that you should try shaking a much larger surface to see if the particles keep on moving in the same directions, or if they settle into islands or if other effects are observed. Also, try a round surface. Needless to say, this interests me... please do one of those longer videos, or a follow up when more is known.

[@drosprey]

Awesome job brady

[@davidwilkie9551]

Great demo of why the use of descriptive words for things you can see should be used very sparingly for those you can't see. Beads are not gas molecules, and only partially act in similar manner.

[@msungo777]

From what I can tell, this experiment is not done in vacuum, which means there are air particles in the mix to consider. One could imagine that at a certain amplitude, glass particles chaotic motion gets overtaken by the motion imparted by the piston in the axis its pushing in. The granules moving up and down together as a plane, would basically make a floating piston, that would create air streams of air particles in the mix, instead of them also behaving chaoticaly.

[@UninstallingWindows]

@EveryoneIsBoring Actually on their channel(sixtysymbols), there is a video explaining it with a different example. Basically, the more closer together the beads get, the more they collide with each other...and thus waste their energy. Less energy..less movement, less movement, less temperature/pressure, less pressure, more particles.

[@TheOtherWes]

Great video, rather interesting

[@boldger13]

Maybe the box slightly bends when vibrating violently. The misshapen box therefore encouraging the granules to migrate towards locations of concavity. Thumbs up to get the scientist to answer this post!!!

[@atrumluminarium]

Is there somewhere I can read all about this like the equations and statistics of the system? Because it actually does seem like a very interesting topic.

[@tyler7480]

So... Why does the pressure decrease when there is a higher density of particles in one area?

[@saitaro]

magic

[@jasdeepsinghgrover2470]

As the particles vibrate horizontal motion seems to be generated by oblique collisions​ and it's energy is lost in collisions​ with walls... so if at some frequency particles come into resonance and number of oblique collisions reduce (probably the particles start oscillating parallel to each other and with phase difference nπ) and only vertical collision occur then the pressure due to random horizontal motion reduces... I am not a scientist or an engineer but just guessing a probable reason

[@sansamman4619]

because there is a more exerted force on the object in a more simple way, there are more things that try to replace you.

[@TheinMoka]

Pressure decreasing due to particles being near each other has everything to do with particle interaction. In a quick thought experiment, think about what would happen if all these particles had a magical force of attraction, where they wanted to stay close together. Then it's reasonable that you would expect clumps of matter to form. In this case, the "magical force of attraction" is the energy loss due to oblique collisions between particles. (There's another sixty symbols video that discusses this in more detail).

[@glgpgpu5686]

In the less dense area, particles move faster, and therefore more motion, which is what's called 'more pressure'. In the higher density area, the particles move less (presumably losing their energy to collisions or what have you), and moving less means 'less pressure'.

[@Herstead]

Having watched a lot of Sixty Symbols and other similar videos lately the pattern reminded me of matter forming galaxies right after the big bang, but that is probably true of any group of particles that for whatever reason begin to attract one another into denser areas.

[@keystothebox]

@DemiImp Substantially different size particles may account for the behavior, therefore same sized particles that are clean are useful to rule out these issues.

[@Jack__________]

We need a follow up to this video!

[@kingofcobwebs]

No, it makes perfect sense - there will always be another octave higher to reach toward within resonance states. Although it did surprise me at first when the beads at last reached a new field of equilibrium and returned to a gaseous state - awesome.

[@ohwhererehwho]

Insightfully FASCINATING! A new phase transition is observed experimentally in a dry granular gas subject to vertical vibration between two horizontal plates. Molecular dynamics simulations of this system allow investigation of the observed phase separation to find a high-density, low temperature liquid, coexisting with a low-density, high temperature gas moving coherently. The importance of the coherent motion for phase separation was investigated using frequency modulation. Key: COHERENCE

[@HotblackDesiat042]

@thesourceofx Thanks for your input. Perhaps they are not amplifying it to the extent in which limiting occurs. I’m just curious to know if they are reaching, or passing that point in amplitude.

[@Instrumentals4Sale]

- do the patters repeat when the experiment is duplicated? - as in certain frequencies trigger spots to form in corresponding areas. Interesting video!

[@P00P0STER0US]

Good luck with your new science :) We'll check back in 5 years to see where it's going.

[@dapoa2011]

Fascinating. Please can you furnish with the title of the paper in Phys. Rev. E.?

[@pope400]

I love this guy lol

[@HotblackDesiat042]

@HotblackDesiat042 When I speak of limiting I mean the point at which the amplitude of the drive signal is sufficient to extend the piston/solenoid to its farthest extent, thus reaching its maximum stroke. Any increase in amplitude beyond that point will be clipped as the piston cannot extend farther. When the amplitude is pushed beyond this point is would be akin to a square wave feed versus the sine wave feed, as that would be the motion the grains would feel.

[@msungo777]

Basically, what that means, is that there will be wind inside the box, and as a plane of glass particles rise up, and starts falling down, the air would get pushed down, then outwards, which would carry some glass particles with them, forcing them towards edges, so the air pressure in the middle will increase, and decrease at the edges (because there would be more glass granules at the edges), and when you again increase amplitude, the forces imparted by the piston can overcome the pressure.

[@matthewburton9637]

This is so cool!

[@anrade86]

I wish I could thumb up these videos at least a thousand times each!

[@DamianReloaded]

Despite of it's simplicity, this may be one of the most amene and interesting sixtysymbols videos to watch. I agree with @Jan1515 that much of it is merit of the edition. Also because Dr. Tetris seems sounds like a lovable person. heh I wonder if it could be possible to obtain a vacuum zone with this technique in an actual gas...

[@helloitsnicko]

9:35 smiley sand face! :D Ps. Great video, really interesting stuff!

[@butterflygroundhog]

is there a reason why you cant consider the particles as being in a "liquid" at that amplitude? i think it would also be a great thing to look at the physic in a bigger environement, so you can see how the particles react without hitting two layers constantly, to check if the clumping happens again

[@daanevert7807]

+maxime therrien Yes Maxime, I agree with your suggestion to get rid of the 2 layers. I guess getting rid of 1 layer already would give a hint. Does anyone have a link of the relevant publication? Thanks.

[@Gameboygenius]

@frichikendz I'd guess at least part of the reason why that happens is because the liquid is most hot in the middle of the cup and cooler at the sides. Hot water (at least >4deg C) rises and cool water sinks, so small currents are formed which, at the surface, are moving toward the edge.

[@magicicle]

Another good looking prof

[@RobertBardos]

try it in a vaccumn. my theroy is the glass particles are round a bit like an airfoil. as they move rapidly up and down, through the medium of air, the accelerated air flowing over them would cause a pressure drop, hense the clumping tendency from lower pressure air regions. the bernulli principle in action. maybe?

[@Hemenesgard]

Please, put the paper's DOI on the discription.

[@boldger13]

@eltotoX Yes, It is by testing, flat and level but maybe they didn't test the flatness while vibrating at high oscillation. I would also like to know how they measured the level. eg Did they use digital instruments?

[@MrOldprof]

@godlyking3 Yes they would because the base of the cell throws the grains up, and they hit the top of the cell and bounce down again, in zero gravity. And so on. When gravity is present theamplitude of oscillation has to be large enough to overcome the effect of gravity so that the particles hit the top plate..

[@ActiveStorage]

as someone already mentioned, the plate they are using can not be an absolutely rigid body. So the oscillations of the plate and formation of nodes and anti-nodes are inevitable.

[@HotblackDesiat042]

@Jebus495 That's what I was assuming he meant, but I was hoping for a clarification. It does make me wonder what effect changing the gain would hold, if any. Due to the natural limiting effect of the piston (because of the limited stroke) it would be akin to changing the feed signal from a sinusoidal wave to a square wave. Thanks.

[@Ypthor]

Have you ever tried putting in some coloured beads? It might help analyse the movement of individual "particles".

[@piponwa]

Very cool physics!

[@thegreatestoffools]

Cool! Question: given the similarity of behaviour in the equilibrium state between that and gas, would it somehow be possible to make gas behave in a similar coherent, non-chaotic way? If so, how might you go about achieving that?

[@HotblackDesiat042]

@thesourceofx Okay. So my question still remains concerning the natural limiting effect from the piston/solenoid in relation to the feed signal. At what amplitude does the piston's stroke max out and limiting begin? Next, what is the equivalent structure of the feed wave when the particles go from being chaotic to coherently driven?

[@Snagabott]

Did you try the experiment with an evacuated plate? Does that change the frequency where the bubble appear/died out again?

[@VincentVonGoat]

nice. Any thoughts of mixing these experiments with a Brazilian Nut Effect? ie: beads of two differing densities

[@hingeslevers]

What a coincedence. I was just putting rice in a snare drum using a paper funnel and I was thinking about possible pattern forming when playing the drum (the drum heads are transparent) inspired by the earlier video with prof. Bowley.

[@wyvernlord23]

These patterns look amazingly similar to the super clusters in space. Could there be any correlation or no?

[@Teekles]

How does this relate to the pendulum effect? As in when you have a bunch of pendulums set up where the motion can cause horizontal movement , they align them selves to tick together. Maybe the impacts vibrating the glass has something to do with this as well (the vibration waves would have to strong enough to have overlapping waves at somewhat similar frequencies)

[@Kram1032]

Really interesting experiment. I've seen that happen before but like probably most ppl in the world, I didn't pay much attention to it - and thought the container might be sloped or wobbly, heh

[@suivzmoi]

i'd guess that at low amplitudes the granules are oscillated randomly on all three axes,so pressure in all directions are similar, producing a nice uniform distribution of particles.then at a resonant frequency of vibration in one axis (z-height movement of the piston in this case)each particle now resonates in the z axis at the expense of x/y oscillation,such that x/y pressures drop and the particles collect sideways.expectedly the pressure on the glass and baseplate must have greatly increased

[@Gameboygenius]

Have you tried redoing the experiment ona a tray with higher sides, so particles will essentially never hit the lid? What about a tray that is round? Or round and slightly conical?

[@1isaacmusic]

Chladni nodes. They propagate differently when the edge of the surface is clamped and has holes drilled in it, as opposed to a flat square plate with no holes.

[@MrSpreadsheet246]

the effect shown here is occurring not because of the change in frequency, but the change in the amplitude, therefore resonance here does not happen as for resonance you need matching frequencies.

[@pgm3]

Varying the amplitude changes the net energy into the system --wouldn't changing the frequency do the same? At what critical point does the pahse transition (chaos-->stocastic) happen? Is this a function of the phase space betweent that transition and the change "back"? How about higher energies? Do you get other phase changes at higher energies? Finally, just curious--what were you looking for when you found this phenomenum?

[@murdakah]

Perhaps you should try it in a cylindrical chamber, just for interest's sake to see where, if at all it would still clump. The pressure seems to be lower in the corners, is this true?

[@tdjdk]

Agreed, except on the random thing at the start of your comment. Nothing random. Everything still following the laws of physics. It is the human mind (the greatest pattern seeking machine ever discovered) that implies values on what it percieves as patterns

[@solace1369]

Am I understanding this correctly. The lower pressure area has a higher rate of collision. With the higher collision rate the probability that 2 or more particles will hit another at the same time increases thus transfering all that energy into a single particle which ends up pushed into the higher pressure area taking all that energy with it? In other words is the action similar to evaporation?

[@clkbateman]

What is the name/model of the camera that is on the clamp above. also what spec is it. thank you

[@TheZooman22]

Is this effect related to Cymatics in anyway? Has it been tried with a different size frame and a variation of frequency? If there is a relationship between the dimensions of the frame an the frequency, due to harmonics, it will be interesting.

[@TheeImmortalPhoenix]

Very interesting video :)

[@DemiImp]

If you have particles of many different sizes, could you use this to sort through the particles you want? Or do the different sizes interfere with this experiment?

[@Sockheadableful]

I'm wondering.... would this also apply to the expansion of the universe. When the coherency of energy is achieved in a certain state- where particles are in chaos in a certain energy caused by the pressure of the expansion to the observation we just saw with the grains.

[@Teekles]

well, the example i saw was actually metronomes aligning themselves on a board resting on two aluminum cans so that the motion of the metronome would cause the board to move relative to the cans inertial - although metronomes are certainly a type of pendulum =)

[@firelunamoon]

Fascinating.

[@TheButtDepot]

The Box Ghost was this dude's granddaddy

[@azmanabdula]

@boldger13 so even while it doing its "clump up" movement.....it is effected by our gravity? thats weird......so it is not so random......plus does the whole plate move up and down in one movement....one piston or does one side go up and the other down....and vise versa......like 2 pistons not in sync......?

[@dit-zy]

@HotblackDesiat042 @Jebus495, at the beginning he says that he is only changing the amplitude, not the frequency, because amplitude has a greater visual effect on the system, or something like that. So it's amplitude/gain, not frequency.

[@nulliplex]

What's surprising is that when matter is in a solid state (low amplitude), it clumps together and keeps that form. As it gets hotter (amplitude increases), it tends to become more uniform (gasses expand to fill the available space). But in this experiment with solid particles, it's other way around.

[@Psychodegu]

@Atveurf He said the denser areas were hotter so the pressure was lower causing other particles to collect there. If these related then the center of the star would be low pressure and have more particles, or the out side would be hotter with more partials, but less dense. Neither of these make any sense to me, but that is not my field.

[@HotblackDesiat042]

When he says "as we shake it harder" is he increasing the amplitude/gain or the frequency on the piston?

[@Kram1032]

Both harder AND faster. The frequency stays the same. But the total travelling distance increases due to higher amplitudes, which means greater distance from the "zero-level". And greater distance in equal time means faster. The force becomes stronger in that process too. The maximum accelleration increases, the mass stays the same, which means more force.

[@TomatoBreadOrgasm]

I don't think it's dull. I'm curious, though: does this say anything about the accuracy of this model being used to approximate the behavior of gases, or do gases do this, too? Is this massive (PUN) pressure increase in any way effected by gravity?

[@boldger13]

@azmanabdula If it is un-level or warped while vibrating, the grain will migrate towards the lower elevations and expose the higher elevations.

[@yorickbrown73]

@bruzewski That is amazing I quite literally thought the exact same thing

[@bl4ck0p]

@itchBob Any chance of making the simulation software available to download?

[@50rri50]

are you increasing the amplitude or the frequency of the oscillation?