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Avalanches Simulated With 500,000 Ping-Pong Balls

timothy posted more than 10 years ago | from the they-look-so-naughty dept.

Science 56

An anonymous reader submits "Ping-pong ball avalanche experiments have been carried out for the last three years at the Miyanomori ski jump in Sapporo, Japan, to study three-dimensional granular flows. Up to 550,000 balls were released near the top of the landing slope. The balls then flowed past video cameras positioned close to the flow, which measured individual ball velocities in three dimensions, and air pressure tubes at different heights. The flows developed a complicated three-dimensional structure with a distinct head and tail, lobes and 'eyes.' See for yourself, it's quite interesting!"

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56 comments

Hmmmm... (1)

Gogo Dodo (129808) | more than 10 years ago | (#8097066)

Re:Hmmmm... (2, Interesting)

srmalloy (263556) | more than 10 years ago | (#8100755)

Were these supposed to be the avalanche victims?
Actually, yes, but not deliberately.

I remember running across references to this research before; apparently, the research staff, as part of a press conference, decided to stand on the slope when they dumped the ping-pong balls to give the photographers some dramatic photographs. After all, they were just ping-pong balls, right? Too light to do anything, right? Well, if you look at the image sequence one [hokudai.ac.jp] ,two [hokudai.ac.jp] , and three [hokudai.ac.jp] , you'll see that the researchers discovered that while one ping-pong ball has a trivial impact, half a million of them is another thing entirely, knocking people off their feet.

Re:Hmmmm... (1)

Libertarian_Geek (691416) | more than 10 years ago | (#8102326)

Can't resist...again.....
It took balls to stand in the way.
I'm so ashamed...

Pic of project leader (1)

NiceGeek (126629) | more than 10 years ago | (#8097069)

Pic [tvacres.com]

If you don't get the joke, you're too young :)

Re:Pic of project leader (1, Funny)

Anonymous Coward | more than 10 years ago | (#8097082)

no, you're too old ;)

Re:Pic of project leader (1)

NiceGeek (126629) | more than 10 years ago | (#8097087)

Yes I'm an idiot. My memories are fuzzy :(
Mr. Moose [tvacres.com] was the ping poing ball guy.

Re:Pic of project leader (0)

Anonymous Coward | more than 10 years ago | (#8097311)

Yeh Mr Moose. Here's a better picture [sptimes.com] . Mr Rabbit conned him out of carrots. Boy that has been a long time. It's funny I can remember Mr Rogers almost as well and I never watched his show. I guess SNL should have made fun of Capt. Kangaroo then maybe we would all remember him better.

One question (-1, Troll)

Compuser (14899) | more than 10 years ago | (#8097076)

Why?

Re:One question (1)

CPD (535082) | more than 10 years ago | (#8097124)

wow! forget RTFA. try RTFP:

"to study three-dimensional granular flows"

has /. reached a new low? and yet i still read it. :)

Re:One question (2, Informative)

WhiteBandit (185659) | more than 10 years ago | (#8097144)

Yeah, you figure if he's curious enough to take the time to post "why?" he'd be curious enough to CTFL! (Click the fucking link).

Anyway, clicking around the site, this prime example of what it's all about:
My current research is concerned with the dynamics of avalanches. Avalanches are sometimes treated as a special sort of granular flow. These have been studied for a long time but because they can have solids, fluid and gaseous properties satisfactory theories do not exist except in special situations. An excellent starting point is Taguchi's Powder Page. To understand these flows better a series of experiments was started last year of ping-pong ball avalanches on a ski jump in the outskirts of Sapporo. Up to 300,000 ping-pong balls were released from the top of the landing slope and their subsequent motion analyzed using video cameras. These flows are a much simpler than real avalanches but they do have similarities and any model that cannot explain these flows will certainly fail on real avalanches. I am developing a model to predict these kind of flows.

Re:One question (1)

Compuser (14899) | more than 10 years ago | (#8129551)

I wasn't trolling actually. I did click on the link,
saw a few pictures, no description and posted the
question. If indeed they are studying granular flow then
where are equations? That page had only pics.
I assumed this was just some pathetic exuse for
buying a bunch of ping-pong balls.

wtf? (4, Funny)

kurosawdust (654754) | more than 10 years ago | (#8097083)

I am very saddened that these people never thought of using this setup to simulate something orders of magnitude more profitable - the lottery!

"Hey Bill, we've got tons of ping-pong balls and a very elaborate and sophisticated means of tracking their movement - what should we do with them?"
"Uhh, use them to predict the Powerball results and retire on private carribean islands, unique ones of which we own for every day of the month?"
"No, you fool! Avalanche research is clearly the way!"

A victim of this experiment? (5, Funny)

weeboo0104 (644849) | more than 10 years ago | (#8097136)

The only tragic victim of this experiment was this man [go.com] .

A bespecticled bunny rabbit and moose were seen running from the scene.

Re:A victim of this experiment? (1)

Cragen (697038) | more than 10 years ago | (#8098430)

Ah, R.I.P. Captain Kangaroo. He would have enjoyed the parent post. Funny, as the show was always in black and white, I never associated Mr. Green Jeans's name with his overalls. Whooo...

cragen

Re:A victim of this experiment? (1)

ckaminski (82854) | more than 10 years ago | (#8099240)

Really? I distinctly remember it being in color...

Cap'n Kanga: BW & Color (1)

UrgleHoth (50415) | more than 10 years ago | (#8101178)

Captain Kangaroo started in B&W in 1955, but went color in 1969. Check it out here [fiftiesweb.com]

Re:Cap'n Kanga: BW & Color (1)

PD (9577) | more than 10 years ago | (#8109308)

For me, the Captain was never in color. My family didn't get a color TV until 1978 when I was 10 years old.

That never stopped me from loving the Captain. I still think back to those days with a lot of fondness, and great amazement that I would crawl out of bed before 8 AM to watch him every day.

The hardest part... (4, Funny)

stefanlasiewski (63134) | more than 10 years ago | (#8097149)

I hate ping pong avalanches.

The hardest part is digging yourself out with nothing but a ping pong paddle...

They may have been prepared for ping-pong balls... (1)

weeboo0104 (644849) | more than 10 years ago | (#8097194)

but somehow I doubt their webserver is ready for the ensueing avalanche of slashdotters!

got balls? (1)

understyled (714291) | more than 10 years ago | (#8097706)

me: [reading site] oh cool, ping pong balls. shitloads of em. shitloads of anything is good. clickety. oooh lotsa videos. hrm. "The files are mostly a few MB in size." cool. interesting.. uhh sure bottom camera. clickety.. save as.. program files, fine. clickety.. 33 FUCKING MEGABYTES??

these motherfuckers got balls of steel, i say, serving 102 avi's at like 25 megs a pop. i would think doing something like that willingly implies confidence in one's ability to handle large amounts of bandwidth.

Re:got balls? (1)

illuvata (677144) | more than 10 years ago | (#8098049)

especially if you consider that one of the 20 meg avis only takes about 4 seconds

its no coincidence (-1, Troll)

Anonymous Coward | more than 10 years ago | (#8097215)

That this many ping pong balls can be found in Asia.

Hmm... (3, Interesting)

shadowbearer (554144) | more than 10 years ago | (#8097217)

This is an interesting experiment and all, but it resembles a real avalanche about as much as computer climate models resemble real weather.

A actual avalanche is orders of magnitude more complicated. It'd probably be easier, and much more informative, to simulate it on a computer, actually.

It does make for some good eye candy, tho, and I'd bet it was a whole lot of fun. As a serious scientific tool, it's probably not very effective in this day and age, given the better tools out there.

As a teaching tool, however, it has astounding potential, especially in primary education.

Just as an aside, I've witnessed a few large avalanches. I was fascinated (and horrified) at the time; the fascination came from observing the complex flows introduced by various things such as the underlying terrain, trees, assorted rocks, etc. I remember thinking the last time that it was a good demonstration of fluid flow dynamics. The horror came from watching several skiers get caught up in the snow flow. They survived, thank Guh.

(Disclaimer: IANAMathematician).

SB

Re:Hmm... (4, Interesting)

mhesseltine (541806) | more than 10 years ago | (#8097369)

From a recent article in DesignFax Magazine [manufacturingcenter.com] , you might be surprised at the kinds of things you can model using simple bouncing-ball-like objects. Everything from giant dump trucks to laser toner.

Re:Hmm... (1)

shadowbearer (554144) | more than 10 years ago | (#8105965)


That's an fascinating article; thanks. They were talking about computer software, tho (I read it in a hurry, did I miss something?)

BTW, I believe that the truck on display at the Hibbing, MN Mining Museum is a 797. It's been a while, but the scale is right.

SB

Re:Hmm... (1)

mhesseltine (541806) | more than 10 years ago | (#8106820)

No, you didn't miss anything. The article is about software simulation and cross-industry licensing. However, it is a way to show how diverse problems can be modeled using similar techniques.

Re:Hmm... (2, Informative)

pipingguy (566974) | more than 10 years ago | (#8109090)

you might be surprised at the kinds of things you can model using simple bouncing-ball-like objects

Yeah, but I think the parent was referring to the lack of thermodynamics-type stuff, like snow or ice's reaction due to the heat of friction.

Discovery.ca recently had a short spot on some kids studying freezing blown bubbles, see http://www.exn.ca/video/?Video=exn20040126-snowbub ble.asx.

Re:Hmm... (0)

Anonymous Coward | more than 10 years ago | (#8097373)

ppsshshht WHAT THE FUCK do you know?

Re:Hmm... (4, Informative)

Cecil (37810) | more than 10 years ago | (#8097750)

A actual avalanche is orders of magnitude more complicated. It'd probably be easier, and much more informative, to simulate it on a computer, actually.

The same thing could be said about an avalanche relative to most of our fluid dynamics models. It is still orders of magnitude more complicated. Which isn't to say that our models aren't quite accurate, they are. But at the same time, they're merely a 'good enough' oversimplification of what's really going on.

Fluid dynamics are an extremely difficult thing to model, and even more difficult to compute. They could challenge most of the supercomputers on the top500 list [top500.org] .

In fact, the top computer on there, Earth Simulator, (at well over double second place) has one of it's two primary objectives being the calculation of relatively simple fluid dynamics models across the Earth's entire oceans.

So, to put it summarize my point here, the best fluid dynamics models we have are extremely expensive to compute, and they are still not perfect. The best way to better understand, and therefore better model, what is happening, is still to experiment with real physics. This experiment will help us develop faster-but-still-accurate models, or extremely precise models for fluid behavior. Either way, recording the locations of each 'particle' as they flow is actually research and will provide a solid set of data for future research to build on.

Disclaimer: I work in the petroleum industry, and therefore only have experience with extremely high pressure/small scale fluid dynamics. My extrapolations may not hold true to the broader field of fluid dynamics.

Re:Hmm... (3, Interesting)

gtapang (709419) | more than 10 years ago | (#8098229)

That is true. Aside from the difficulty in simulating such systems, it is also hard to do an actual experiment that will correspond exactly to your simulation.

Furthermore, a model is exactly what it is-- an approximation of your actual complex system. There would be some details that would be left out to simplify the model while keeping the interesting phenomena intact.

Using an actual system like the ping-pong experiment would still be an approximation to an actual avalanche but it provides a reasonably controllable situation and a level of detail that would be accessible to the investigators. And it generally would proceed much faster than simulating it in a computer.

We were in a similar situation in a research involving escape panic dynamics [pnas.org] where the behaviour of agents (read: people) moving out of an enclosure were looked into. This would be akin to looking at the exit dynamics of people in a fire or in a football stadium in a a riot.

We did simulate escape panic [doi.org] but later on we used mice to look at the models in a real system [nature.com] . It turns out that the model reasonably gets some of the features of the dynamics but would miss out on things not explicitly included in the model, like herding behavior.

Re:Hmm... (1)

pipingguy (566974) | more than 10 years ago | (#8109249)

Disclaimer: I work in the petroleum industry, and therefore only have experience with extremely high pressure/small scale fluid dynamics. My extrapolations may not hold true to the broader field of fluid dynamics.

I found this interesting: Cheng Rotation Vane. [chengfluid.com]

Intuitively, it seems to make sense: if a typical flow disruption pattern is known (and contained, as within a piping system), then it should be possible to counteract that disruption pattern. Of course, the upstream conditions need to be stable for this to work.

Re:Hmm... (0)

Anonymous Coward | more than 10 years ago | (#8098770)

This is an interesting experiment and all, but it resembles a real avalanche about as much as computer climate models resemble real weather.
So it's an extremely accurate resemblance, is that what you're saying? Because modern models of weather are very, very good indeed. Skipping over your confusion about the difference between 'weather' and 'climate', that is.

Re:Hmm... (1)

shadowbearer (554144) | more than 10 years ago | (#8106116)

Actually the error rates in weather models are pretty high yet. Climate models are getting much better, but forward prediction with them is also very error prone.

No confusion, just late and the finger-brain interface was fuzzy :)

SB

Re:Hmm... (2, Insightful)

Lars T. (470328) | more than 10 years ago | (#8101970)

First of all, look at what this post [slashdot.org] quotes from the site. The problem with avalanches (for the simulator) is that they are made up of a) snow (fluffy ice crystals) and b) air. They don't act like simple fluids.

Re:Hmm... (1)

shadowbearer (554144) | more than 10 years ago | (#8106085)

The study of avalanche flow falls within a field known as Geophysical Fluid Dynamics. Yes, there are a lot of similarities; what you're describing is known as a "power snow" avalanche; "dense snow" avalanches are considerably more complicated.

Some interesting reading

avalanche.org [avalanche.org]

SB

Re:Hmm... (1)

sulli (195030) | more than 10 years ago | (#8104359)

Yes, true, the mathematics are such that it's not much of a simulation, but damn that looks like fun.

Mining Simulations (3, Interesting)

trinitrotoluene (713170) | more than 10 years ago | (#8097230)

I went to the Open House for the mining engineering program at my university (Queen's [queensu.ca] ) and one of the professors showed us how they use computer simulations to model rock interactions. The simulations modelled the behaviour and interactions of thousands of sample rock particles. Really interesting stuff. I guess this kind of test is where they get the raw data to develop these computer models.

Mining engineering is also cool because there is a required explosives and blasting course in second year.

looks like... (1)

RalfM (10406) | more than 10 years ago | (#8097497)

That picture [hokudai.ac.jp] totally looks like this animal [google.com] . Illustrating other evolutionary principles somehow?

R

Re:looks like... (1)

WayneConrad (312222) | more than 10 years ago | (#8097544)

What evoluationary principle would that be? That badgers are made of ping-pong balls falling down a ramp?

The similarity (I have to squint to see it; perhaps I'm lacking imagination) only illustrates that the brain sees patterns wherever it can. It's why people see Elvis in the fridge and hear their coffeepot talking to them.

Re:looks like... (2, Funny)

PatrickThomson (712694) | more than 10 years ago | (#8098264)

But my coffeepot does talk to me!

Re:looks like... (0)

Anonymous Coward | more than 10 years ago | (#8098777)

What evoluationary principle would that be? That badgers are made of ping-pong balls falling down a ramp?
Further research is obviously indicated in the mushroom/ball bearing and snake/beachball fields.

Re:looks like... (3, Funny)

jafuser (112236) | more than 10 years ago | (#8100288)

Maybe this means we can use badgers to predict avalanches! =)

Re:looks like... (1)

pyrote (151588) | more than 10 years ago | (#8106579)

Maybe this means we can use badgers to predict avalanches! =)
or even ... ahhh... snakes!

sorry, had to.

Re:looks like... (1)

Garridan (597129) | more than 10 years ago | (#8103357)

If by "this animal" you mean "this animal's pelt", I'd have to agree. Perhaps we could postulate some theory about badger pelts being flat. And sheets of pingpong balls sliding down ramps being flat. The possible correlations are simply stunning. We could fill a box with badgers, and try and make an avalanche. Or maybe, try and mate badgers with avalanches to make a half-badger half-avalanche mix. Ferocious little beast. Cold, too. It could be the ultimate weapon on hilly terrain. We'd finally be able to beat the Swiss with their damned knives!

Re:looks like...badgers? (0)

Anonymous Coward | more than 10 years ago | (#8110065)

Badgers? We don't need no steenking badgers!

Re:looks like... (1)

The Evil Couch (621105) | more than 10 years ago | (#8113197)

so what you're saying is Badger, badger, badger [evilcouch.com] ?

Motion plus mass equals life (0)

Anonymous Coward | more than 9 years ago | (#8136394)

We are seeing in this picture not a badger, but a manifestation of primal forces.

In old times they called them demons. Now we call it quantum phenomena.

There is a lot to learn about the universe yet.

Gotta love that Engrish (1, Funny)

pompousjerk (210156) | more than 10 years ago | (#8097540)

"Click on any of the pictures to get an enlargment."

The original ping-pong ball avalanche inventor (0, Redundant)

mbstone (457308) | more than 10 years ago | (#8097742)

Didn't Captain Kangaroo [tvacres.com] invent the Ping-Pong ball avalanche back in '55??

Great Potential (1)

Jetboy01 (550638) | more than 10 years ago | (#8097793)

This would make an excellent addition to the spectacular gameshow 'Takeshi's Castle'. The opportunities for hilarity are just endless... maybe

Avalanche Rescue (3, Funny)

fuzzybunny (112938) | more than 10 years ago | (#8098460)

This is pretty cool, sort of an "avalanche light" experience.

They could rescue people with chihuahuas carrying cans of diet pepsi.

Not very accurate (1)

spin2cool (651536) | more than 10 years ago | (#8101655)

Though it's no doubt an interesting experiment that might lead to further research, it's a long way off from modeling real avalanches.

Ice and snow crystals vaprorize, recrystalize, and form bonds in enormously complex systems, unlike ping pong balls, which just bounce off each other.

An article documenting some of the research being done on avalanche snow's state changes and shifts in stability can be found here. [sciencenews.org]

Nearby... (1)

Tablizer (95088) | more than 10 years ago | (#8103077)

Hey, you lost the ball again, Sureshot. Go find it.

Okay....wait, here it is.
And a second one!
And yet another......and another....

Oh oh, Ruuuuuuun!....

shocking.... (1)

npistentis (694431) | more than 10 years ago | (#8115330)

advanced 3d video and ping pong... its amazing this hasnt caught on earlier among the geek community!

With one order of 550,000 ping pong balls comes... (1)

Business King (599197) | more than 10 years ago | (#8121317)

... 4 merry maids, 1 golf ball collector, and a fortune cookie. Can I have sauce with that?
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