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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?
Now when they start talking about "phase shifting" on Star Trek, it's not just technobabble - it's science!
52 Weeks, 52 Religions with John Hummel
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
precisely because of the difference between density properties of ice and water.
Otherwise every bit of liquid water would have stopped being liquid and that's all she wrote 'cause we wouldn't be here.
MSBPodcast.com The opinions expressed here are my own. If you don't like 'em... Think up your own stuff.
Parent said: So given that this is about natural phenomena (like Bee flight -- see previous), can we expect to see ID and anti-ID arguing about what this means? Or can we just stick to the physics and call it that?
And got rated insightful. This comment (except for the 'see previous' part) could be applied to every slashdot article ever posted in the science section and wouldn't be terribly offtopic.
Is Intelligent Design the new karma whoring goodness?
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.
They killed Star Trek.
Rob
Could this be used also to better apply physics to videogames? Perhaps enhancing weather simulations for RTS games or physics properties for FPS games?
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
Oh man, there ought to be a hall of fame for comments like that...ow...ow...ow...
While multiphase flow has existed for quite some time, this is quite an interesting development. The article was thin on details of their experimental setup, but I would be interested to see their cfd code (if they wrote their own) or if they used a commercial code. Also, I am curious as to their meshing strategy. Lastly, how did they verify their results? My best guess would be to let the simulation run in a transient state until it reached a steady state point and then correlate that to a measurement in quality of the fluid over time, and then compare progressions? My experience is with mainly single-phase flows, but eventually I will need to look into this area.
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.
No.
From now on, every conversation in the U.S. that regards science in any way must stoop to a lowest common denominator argument, and all statements that are backed by empirical evidence must have the caveat, "but, only if science is right," in front of them.
One would think that when the Catholic church came out and said, "dude, we don't like Intelligent Design either," that things would have died down a bit.
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.
But that's the point of ice4... the crystal lattice is denser than regular ice, as well as liquid water. The real reason ice4 doesn't work is that it is a less stable lattice, with greater energy stored in the H-bonds... entropy tells us regular ice is more stable.
"Trolls they were, but filled with the evil will of their master: a fell race..." -- J.R.R. Tolkien on Olog-hai
Given infinite time, both the spontaneous emergence of life AND the spontaneous emergence of an intelligent designer who creates life in His Own Image(TM) are going to happen sometime:-).
Friends don't help friends install M$ junk.
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."
I want to see a system that can model solid particles, liquids and gases within the same system so that I can finally model biosolids digester gas mixing. So far I have not come across anything that can do it, and so there is no way to tell if a gas mixing system works or not, until you take the digester off-line and shovel out the grit. From what I can tell, they are generally designed using a mixture of experience and guesswork.
If my call is important, why am I talking to a recording?
From that enthusiastic report I gather they will receive the Nobel Prize eventually. I think the man who wrote a groundbreaking chemist program in the 1960's also received the prize some years ago. Wake up, hackers, there is still hope.
Is the transition between gas and plasma a phase transition of the same kind? I wonder if this research would help with fusion? I imagine there is a lot more going than a simple phase transition (e.g. gravitational and electromagnetic effects) but it might be one part of the puzzle.
Beer is the grossest tasting thing ever. Same with most alcoholic drinks. Any drink, remove the alcohol, I can almost gaurantee it'll taste better. But the alcohol's there for the "special effects" it does to your body. I'm pretty sure many may object to what I just said and what I'm about to say, but I can somewhat understand why people would drink beer (obviously for the alcohol content and not the taste), but I can not find any reason why anyone would drink non-alcoholic beer.
HD Trailers
just sound like a bloody new fansy name for
Newton's Law of Heating/Cooling
Of course, at least according to our current state of knowledge, we've only got the one universe, which does not have an infinite extent in the time direction. However, I will grant that the question isn't 100% closed, and if one manages to create one's own universe, the rules pretty much go out the window :)
Damn....some more buzz words I can use in my PowerPoint presentations.
Given infinite time, we must have an infinite number of universes:).
Not to mention the exactly accurate account of the creation of this universe, along with an infinite number of variations that are slightly to horribly wrong 8-0.
And you wonder why the IDrs are so concerned about the long range implications of Mr. Darwin's realization...
You mean Ice-9.
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
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.
...in the coffin of Intelligent Caffeination.
It's a corollary of Godwin's Law: "As any slashdot discussion about science grows longer, the probability of a comparison involving Intelligent Design approaches 1"
of course, biting monkeys is not to everyone's taste - Konrad Lorenz
Or the press release comes first? I am interested in seeing something more meaty. I have found some related papers but not a specific one. That or just lazy.
Slashdot: Where nerds gather to pool their ignorance
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. :)
What was your grade?
I feel fantastic, and I'm still alive.
Owned!
"which does not have an infinite extent in the time direction."
Don't need it if you have infinite extent in 3D space (a reasonable assumption), everything that can happen is happening right now, not once but an infinite number of times. God is outside the Universe so the question of wether God can exist or not is philosophical.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
A comment can't be modded Troll, Flamebait, AND Offtopic unless it gets some points first. Seing as how ID pertains only to biological systems, I haven't a clue what gp is talking about.
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....
Oops. That's what I get for posting hours past my bedtime.
"Trolls they were, but filled with the evil will of their master: a fell race..." -- J.R.R. Tolkien on Olog-hai
This is a major deal because there are still LOTS of things that aren't so clear about fluid flow and thermodynamics. For example, one of the things I personally deal with is two-phase flow going through safety relief valves. (ie: you have a liquid and a gas going through the valve). It looks easy. It isn't because it really is "voodoo" as to what actually goes on in that situation. Since there is a pressure drop across the valve, all kinds of weirdness takes place (flashing, etc) and it makes it difficult to predict what the ratios are for liquid / gas. And the ratios can have an impact on the size of the valve. An improperly sized valve is extremely dangerous because it could cause your system to, literally, blow up due to overpressure.
Having a mathmatical model might help us determine what the behavior should be and thus, will create safer and better understood products.
It's kind of like replacing "trial and error" with actual understanding. But this is a GIANT step forward for a very "mature" industry.
(OT) It's reasonable to assume that whatever created the Universe had the same amount of energy as the Universe, ergo the Universe created itself without any God fiddling with things.
thank God the internet isn't a human right.
(OT) Posts like these are the reason I wade through the dreck on /.! Thanks folks!
<cynicism>
Everything else in the U.S. has warnings on it to "protect" idiots from their own stupidity. Why should science not be subject to the same societal "obligations"?
But slightly more seriously, I think this wouldn't be such a big issue if we weren't so obsessed with getting everyone interested in and aware of science, when the simple truth is most people either just don't care or aren't capable of understanding. The "you too can understand Science" movement has convinced everyone that they have the ability to judge the merit of complex research.
If we want more people to understand science, they need to go to school. Reading pop sci books and magazines, watching pop sci TV specials, etc. is not making the general public smarter. It's making them more overconfident in their limited comprehension.
</cynicism>
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
Well, the point of their algorithm -- and I haven't read the PRL paper either -- is that it's off-lattice. It's an open question how much off-lattice systems, e.g. real fluids, differ from the lattice models you mention, when it comes to critical behaviour. I think the critical exponents are the same, but other stuff will vary.
So in that sense, if they've come up with a better simulation algorithm for critical fluids, it's a big deal. At least, it is for chemical engineers, although I grant the physicists may be less impressed. The chemical engineers are, as a rule, interested in detailed information about a particular, chemically-distinct critical fluid, like critical CO2. That makes them different from the physicists, who are more interested in universal models of criticality, such as are easily illustrated with an Ising model.
Chemical engineers have been interested in using supercritical CO2 for extraction processes (like decaffeination) for a long time, because the fluid appears to be a powerful solvent, meaning it can dissolve away your impurity of choice, but it has zero work-up and clean-up issues: you just drop the pressure a tad, and your fluid turns into plain gaseous CO2 and puffs away, no mess no fuss.
I completely fail to see any application to fuel cells, however. Nothing supercritical in there that I know about.
Oh wait! I just got confirmation from a second source; the internet! It must be true.
><));>
Trouble is due to the placebo effect, it might fool the brain so well that it behaves as if it is indeed caffeinated.
See Neuropharmacological Dissection of Placebo Analgesia,The Neurobiology of Placebo Analgesia and "13 things that do not make sense".
Then there's also the homeopathy thingy - see num 4 in the newscientist article.
I suppose I am not explaining myself well. How's this: modeling doesn't necessarily help to understand the underlying reason why the system acts that way.
Take critical exponents. We can use a simple model and use simple calculations. Some of the critical exponents we find match closely with experiment. Some do not. Then we do renormalization group theory. The critical exponents we find match much more closely with experiment... but did we learn anything about the underlying cause? We mainly confirmed our original model and just found a new way of doing the calculations. Perhaps I am mistaken. My understanding of renormalization group theory is limited but the basic idea there.
On the other hand take the electron-phonon interaction model of superconductivity. That greatly enhanced our understanding of (the reasons behind) superconductivity.
In the case of this article however it seems like they just solved a model for phase transitions that had not previously been solved. Perhaps even it was a model that had been solved but they did it a different way or used one less assumption. The point is I saw nothing that indicated that we now have a better understanding of what happens near the transition temperature. As far as I know scientists already have a very good idea of what happens.
I drink decaf coffee BECAUSE it has caffeine in it. It has a little bit, just enough to pick up my system. I regular cup of coffee leaves me jittery and sometimes tanks my blood sugar. A cup of decaf picks me up and makes me more alert without the jitters and more importantly decaf doesn't mung up my blood sugar.
Mmmmmmmm..... decaf.... good schtuff......
Caffeine is a poor substitute for sleep. And if you get enough sleep, you have really weird dreams...
--LWM
Well, the way I see it a good model will tell you a bit of both - what to expect and why. You can use simulations to get to the heart of behaviors and then match it against the huge slew of things going on in any real physical system. For example, in crystal growth. You can get dendrites and fingering instabilities from a huge number of different systems. It could be fluid flow (pressure field) or solidification (temperature field) or accretion (concentration field). But these all end up being treated by the same mathematics, and the mechanism is quite general.
So what does that let you know that you couldn't know before? Well, if you have a system with multiple such fields you can perhaps determine which one is significant by looking at the selected wavelength and comparing to the predictions from the model based on the diffusion coefficients. So given a complicated physical system that exhibits particular qualitative behavior you can narrow down the possible causes of that behavior.
If you have absolutely new qualitative behavior that you simply cannot understand, a computer model lets you change things which aren't physically possible to change in order to determine what the relevant degrees of freedom are. If I have some block of superconductor, I can't normally change the coherence length or penetration depth and see what happens (at least, not without changing other variables, e.g. the temperature). In a computer model I can do this and see how the behavior of the system changes with those alterations.
It's true though that it's less useful when there isn't some qualitative behavior you want to explain, but rather a single number - there might be many difference causes for a Tc being 10K above or below where you expect, and it would be nigh impossible to say 'well, I adjusted my model and got this Tc so I must understand the source of that'. But if you have something more distinct - a discontinuity in some property that shouldn't otherwise exist, then you're looking at a qualitative change in the behavior which might point to some underlying change in the symmetries of the system - e.g. a phase transition of some sort. In which case constructing a series of models to find out just what sort of symmetry breaking gives you that discontinuity can shed light on what the underlying physical mechanism is.
In this article, what's interesting is more that this is a new numerical technique at measuring the properties of a class of models, rather than this being the solution of a particular model. It's akin to a new experimental technique - on it's own, it doesn't tell you anything, but when you apply it to a system of interest... For instance, while one might argue that regular liquid-gas transitions have been studied to death, you could probably apply this sort of thing to more exotic things such as multi-species fluids, charged fluids, granular fluids, fluids dominated by quantum mechanical effects e.g. electron gasses, etc. Time will tell.
Wow. That is a cynical viewpoint. I don't really know if it's 100% true. I think that most science is fairly accessible. I mean, I'm pursuing a PhD in the Fall, but, even things that I research, I feel that I could explain conceptually without much difficulty. The underlying mechanisms probably require a fair level of education, but the basic idea can be explained without any great difficulty.
I'd say that that covers easily 50% or so of what I am in to, but that's plenty of conversation fodder for magazines. One of the professors that I work with in my current research assistantship has given interviews to a number of magazines, detailing, at a very high level, our current research.
I hope he doesn't fail me next semester ~Shan
If you want people to learn that stuff--how to think scientifically--you have to get them while they're kids.
But that's not going to change the people who just don't care about it. People care about what they care about. Unless you can turn science into something they care about (like the "great space race" to beat the "commies"), which is tough to do while remaining honest, they're not going to change or make sacrifices.
I think I'm coming off even more cynical than I mean to. I think that a certain portion of the population is going to be a "lost cause". They are too busy just getting by to try to care about something that's not going to put food in the pantry, shoes on the kids' feet, and tires on the car today. And there's another segment that's frankly just too old. They're sure they've already got it "figured out" and you can't teach an old dog new tricks.
So, again, I say we let the old dogs be, and get to work on the pups. But don't expect them all to come out perfect.
Sweeping generalizations, maybe. But it's the best explanation I can think of for all the things I've seen people do.