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Phase Change in Fluids Simulated
brendotroy writes "After decades of work by the physics and computer science communities, scientists at the University of Rochester have finally created a mathematical model that will allow scientists to simulate and understand phase changes. This discovery 'could have an impact on everything from decaffeinating coffee to improving fuel cell efficiency in automobiles of the future.'"
could have an impact on everything from decaffeinating coffee
So it's going to be used for evil!!!!!
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
Perhaps in the future, a swimming pool will hold 10,000 Litres of data by using phase changing properties to store binary computer data.
Saskboy's blog is good. 9 out of 10 dentists agree.
I doubt I'm the only one who remembers an article about some breakthrough opening the doors to making decaffinated coffee beans. So far, hasn't happened. Between this and today's other scientific breakthrough of bumblebee flight, are we any closer to a safer and smoother cup of decaf coffee?
I see this being apply to video games as the next Lens Flare fad!
Demented But Determined.
The above gives an introduction to phase change as it is considered in terms of Complexity Theory. Approaching phase change through complexity theory, even for an outsider like myself, gives insight into how far reaching are the results of insight into phase change.
"Academicians are more likely to share each other's toothbrush than each other's nomenclature."
Cohen
phase change is hardly fun. After a recent visit to TacoBell I changed a solid into both a liquid and a gas is less time than it took me to get home in my car, after which both my girlfriend and my dignity evaporated.
http://science.slashdot.org/article.pl?sid=05/11/3 0/168239&tid=126&tid=14
MEDIA CONTACT: Jonathan Sherwood (585) 273-4726, jonathan.sherwood@rochester.edu
January 6, 2006
Phase Change in Fluids Finally Simulated After Decades of Effort
Eldred Chimowitz and Yonathan Shapir
Everyone knows what happens to water when it boils--everyone, that is, except computers. Modeling the transformation process of matter moving from one phase to another, such as from liquid to gas, has been all but impossible near the critical point. This is due to the increasingly complex way molecules behave as they approach the change from one phase to another. Researchers at the University of Rochester, however, have now created a mathematical model that will allow scientists to simulate and understand phase changes, which could have an impact on everything from decaffeinating coffee to improving fuel cell efficiency in automobiles of the future. The findings have been published in Physical Review Letters.
"This problem has baffled scientists for decades," says Yonathan Shapir, professor of physics and chemical engineering at the University of Rochester, and co-author of the paper. "This is the first time a computer program could simulate a phase transition because the computers would always bog down at what's known as the 'critical slowdown.' We figured out a way to perform a kind of end-run around that critical point slowdown and the results allow us to calculate certain critical point properties for the first time."
"Critical slowdown" is a phenomenon that happens as matter moves from one phase to another near the critical point. As molecules in a gas, for instance, are cooled, they lose some of their motion, but are still moving around and bumping into each other. As the temperature drops to where the gas will change into a liquid, the molecules' motion becomes correlated, or connected, across larger and larger distances. That correlation is a bit like deciding where to go to dinner--quick and easy with two people, but takes forever for a group of 20 to take action. The broadening correlation dramatically increases the time it takes for the gas to reach an overall equilibrium, and that directly leads to an increase in computing time required, approaching infinity and bogging down as the gas crosses the point of phase change.
To illustrate the effect, imagine a perfectly pure and still lake. If you drop a pebble into this lake, its ripples would spread outward, dissipating until the lake had returned to a calm equilibrium again. But, if you were to take this impossibly perfect lake just barely above the critical point and drop your pebble, the ripples would remain as ripples much longer--likely bouncing off the distant shores. This imaginary lake would take seemingly forever to return to its calm equilibrium again.
The research team of Shapir, Eldred Chimowitz, professor in the Department of Chemical Engineering, and physics graduate student Subhranil De created a novel approach to tackle the phase-change process. They devised a computational model consisting of two separate reservoirs of fluid at equilibrium and near the critical point threshold. One reservoir was slightly more pressurized than its neighbor. The reservoirs were opened to each other and the pressure difference caused the fluids to mix. The team let the simulation run until the entire system reached thermodynamic equilibrium. By watching the rate that equilibrium returned, the team was able to calculate the behavior at the critical point. Their simulation findings match predictions and experimental results, including very precise measurements performed in microgravity on the Space Shuttle.
"In principle, it's a difficult calculation," says Chimowitz. "Fluid systems require a different class of models than the common lattice models used by researchers who have studied dynamic critical behavior. These different classes give rise to different dynamic critical exponents and we found them, for the first time, in real fluid systems."
The best known examples of phase changes are perhaps water to ice and
7h3$3 4r3n'7 7h3 Ðr01Ð$ ¥0 4r3 £00|{1n9 f0r. M0v3 4£0n9. --OB1
This is all fine and dandy but does it help us understand the physics behind it? Long before we (the human race) had any idea what gravity was, we could predict the movement of the planets... but no understanding came of this. Same here. Just because we can write a program to simulate observables doesn't mean we understand them any better. This might be a step in the right direction but it just as easily could lead us away.
In short... this does nothing for our "understanding" of phase changes.
Decaffinating coffee? Improving fuel economy?
These are not men!
Latewire
NOT work safe, and disgusting. It's hentai, with terrible body mutilation in graphic, well-drawn detail.
Can it show why lakes don't freeze from the bottom up as water approaches 0 Celsius?
Freezing water is an example of a first order phase transition, involving a transfer of latent heat across a clearly defined phase boundary. Algorithms have been able to deal with those for some time (or so I assume). The big breakthrough here is that these guys figured out how to model a second order phase transition (i.e phase transitions in a supercritical fluid) without incurring infinite CPU time.
Most people are familiar with first order phase transitions (like melting ice or boiling water) but have never seen a second order phase transition. In general first order phase transitions involve a transfer of latent heat, and are noticeably discontinuous- the two phases are easily distinguishable from each other. Second order phase transitions do not involve a latent heat transfer and there is no abrupt discontinuity during the transition, as they occur above the critical temperature and critical pressure, beyond which the liquid and gas phases are indistinguishable.
The article doesn't explain this at all, but the giveaway here is that the reporter talks about the critical point.
I would like to point out that the article is not about plain phase changes, but rather about phase changes near the critical point , where liquid and gas phases become indistinguishable. Predicting ideal phase change behaviour has been done, but the critical point poses some unique challenges.
Languages aren't inherently fast -- implementations are efficient
Could this mean we could see a light emitting fluorescent liquid tube without a 60 (or 50)Hz hum?
The effects of phase shif flickering are known to be horrible for ergonomics.
"NOT work safe, and disgusting. It's hentai, with terrible body mutilation in graphic, well-drawn detail."
Thanks for the heads up! (I had my threshold set too high...)
"Derp de derp."
The funny thing is, the ID people are pointing to the easiest thing for science to prove in regards to a creation, geology and biology. If the ID types were smart, they'd point to all the questions there are with the creation of the Universe, like what the hell happened after the Big Bang, how the hell did something as convoluted as quantum entanglement come to be...and go Clockwork Universe! There is a God!
But no, they want an interactive God and they don't want to learn physics...
About 10 years ago I was taking a CAD/CAM class and the instructor was one of these literal Bible folks, thought the world was 6000 years old and one day he said something about that. So I went home, got a chart of radioactive decay and brought it to class. Next day during a break, I asked him if he believed in the presence of radioactive Radon gas on Earth, he said, "of course I do", I pulled out the chart, said," well Radon comes from the decay of Uranium after around 4.5 billion years, therefore, the Earth is that old." He turned around and never ever mentioned his theories again.
A friend of mine learned the hard way about how water expands as it freezes and its density drops. She put water inside glass Christmas ornaments, then put them in the freezer with the idea of floating pretty ornament-icecubes in her Christmas party punchbowl. She didn't leave any room for the expansion inside the ornaments though. So just as she was readying the hors d'oeuvres for the oven, she heard small explosions in her freezer, and cautiously opened the door to find ice and thin shards of glass all over everything.
She didn't see the funny side of it at the time, but she does now. :)
Go try a Fuller's London Porter. It has flavors of coffee and chocolate. And yes, it's beer.
Coffee flavored beer is called a stout (and the lighter flavored version is a porter). Forget Guinness and Murphy's, they're far too watery. I'm talking a real stout. If you see one, grab a Great Divide Oak Aged Yeti Imperial Stout - it's a drink to behold... But warning, once you travel down the dark path of real stouts, you'll never drink a BMC beer again...
Yup--and the reason that it took 46 years? In part because the researchers involved forgot their first year calculus: they assumed that any function that is infinitely differentiable can be represented by its Taylor series. The assumption is almost always okay in practice, but not, it turned out, in this case; so they wasted decades in unnecessary confusion.
There's a lesson there for budding young scientists....
Is that a kind of metal? Or am I thinking of "phenominium"?
---GEC
I'm but the humble pupil, seeking to snatch the scratchbuilt pebble from the master's fully articulated hand