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354. Vortex line representation. Clebsch variables
Let us continue our brief discussion of behavior of the vorticity field in the Eulerian flow. (and that’s how vortex lines look like in reality… as if you wouldn’t know ) This time I would really like to derive some equations describing dynamics of vortex lines. For this, it is convenient to use so called [...]
353. Vortex line representation. Cauchy invariant
Several days ago I’ve promised in comments to discuss dynamics of vortex lines in turbulent flows, today is probably a good day to start. And the natural starting point of course is the Kelvin theorem and Cauchy invariant. Let us consider an ideal (inviscid, uncompressible) fluid described by the Euler equation and incompressibility condition . [...]
352. 48 years ago
Those were the days of our glory. By us I mean all intelligent people, all passionate, sensible people, all people who are able to discriminate objective reality from the bare wishful thinking. And, of course, people who are able to distort objective reality to match their wishful thinking. But those days have passed. In reality, [...]
351. Girls only
I think, it is a scientifically proved, established fact that women are so much more explicit in conversations between each other than men, isn’t it? Via uzhas_sovka.
349. The question of quality
Last time we had a nice, surprisingly long discussion trying to answer the question how much should you publish in order to be considered a successful postdoc From Michal’s point of view, this is not quantity but quality of your publications that should matter. Actually, I completely agree with this point of view – that’s [...]
348. Trading olympiad
As usual, no physics today, True Geeks, only fun very distantly related to physics is allowed! Interactive Brokers has just announced that the 2009 IB Collegiate Trading Olympiad is now over. What is the idea of the olympics? Naturally, an unspecified number of guys – mostly, students of various universities – each create a piece [...]
347. Numerical simulation of vortices: video of the day
A video by New Scientist magazine featuring some really nice simulations of developed turbulence in the presence of vorticity field.
346. Thermonuclear fusion. Nuclear reaction rates – second part
Last time we have figured out that two factors determine effective rates of nuclear reactions – the probability of quantum mechanical tunnelling through the Coulomb barrier and the probability of nuclear transformation. Let us talk today about the second factor a bit. While the first factor given in the simplest case by the Gamov exponent [...]
345. Lagrangian turbulence: video of the day
A simulation by Guido Bofetta, U. of Torino. Recall that Lagrangian description of hydrodynamics is when you pick a liquid particle and keep track of its motion. Here it is shown how particles are transported by a turbulent flow in the presence of a vortex.
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Micro: Can 2 question provide a common solution? Black holes, information loss paradox and Ultra high energy cosmic rays. ...
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James Ph. Kotsybar: SAGITTARIUS A* -- James Ph. Kotsybar Mysteriously cloaked, obscure despite Interior illuminating glare, Long ...
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cad: The presentation can be found in several formats at http://pirsa.org/08110051/...
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Leo: Ok I have a question: if a black hole is supermassive, say 100 billion solar mass, let's suppose Alice fells int...
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superkuh: I am glad you are back! No more disapointing weekly refreshings of that monkey....
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Ariel Amir: Very interesting, thanks. It indeed seems to be very close to what we discuss here. I wonder whether the distributi...
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