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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.
But is is going to be as fun as the real thing?
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.
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?
http://www.thebricktestament.com/the_law/when_to_
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
>>>Phase Change in Fluids Simulated
Sex with women simulated too. BigFknDeal!
The government which is strong enough to protect you from everything is strong enough to take everything from you.
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.
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
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.
Tasty, but I don't think this is the phase change she was hoping for.
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.
this would be wonderful if they could turn decaff into real coffee...
Dude, just because you find that kind of thing exciting doesn't mean you have to tell the whole world...
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:-).
could have an impact on everything from decaffeinating coffee
FUCK YOU science!
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.
Wierd.
Insert Signature Here
"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
Do you still think this shit is funny, or even mildly amusing?!
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...
Comment removed based on user account deletion
You mean Ice-9.
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
...in the coffin of Intelligent Caffeination.
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. :)
"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.
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
A Beowulf cluster of those babies!
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.
I don't understand what you're saying here. You first say that much, if not all of physics is modeling. Then you back off and say that models do nothing for understanding in physics.
Possibly you mean that there are different levels of models, e.g., thermodynamics vs statistical physics? But in any case, both sets of models are useful and both aid understanding. Perhaps this hinges on your definition of "understanding". But I think you'll find it's "turtles all the way down" with that one. At root it's all models.
God is outside the Universe so the question of wether God can exist or not is philosophical.
Or more importantly, God doesn't interact with our lives so doesn't exist in any tangable way.
Always believe THESE slashdot comments! especially when the are modded up as 'informative' ....gotta go puke now....
(OT) Posts like these are the reason I wade through the dreck on /.! Thanks folks!
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.
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 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
- Take a very clean Pyrex measuring cup and fill it half full of water.
- Pop it in the microwave and heat it until you see a bubble or two.
- Gently open the microwave door, taking care not to jiggle the cup.
- Use a bent wire to agitate the water while keeping your hand (and the rest of your body) well clear of the cup.
If the cup and water were clean enough, it should froth up.(Very clean tap water should work; distilled water should work even better.)
That is a second-order phase transition.
I hope he doesn't fail me next semester ~Shan