Avalanches Simulated With 500,000 Ping-Pong Balls 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!"
Hmm... (Score:4, Interesting)
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
Mining Simulations (Score:3, Interesting)
Mining engineering is also cool because there is a required explosives and blasting course in second year.
Re:Hmm... (Score:5, Interesting)
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... (Score:3, Interesting)
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:Hmmmm... (Score:3, Interesting)
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.