Talk:Perfect fluid

Yeah, merge it.---CH (talk) 01:27, 27 July 2005 (UTC)


 * Perfect Fluids and Incompressible fluids are different. A perfect fluid is an physical concept similar to an ideal gas.  As the article says, there is no shear stresses or viscosity.  These are frequently used in General Relativity.  An incompressible fluid is one where the density does not vary, and div(u)=0.  Incompressible fluids can have shear stresses and viscosity, and are therefore not "perfect".  Incompressible fluids are often used in Fluid Mechanics and in Chemical Engineering.  Due to the different definitions and usages of the terms, I would argue to keep the pages separate. Bluap 12:41, 28 July 2005 (UTC)

"Perfect Fluids and Incompressible fluids are different." Well of course, and it should be obvious that I know that. Where did I (or anyone) say otherwise? ---CH 02:47, 1 July 2006 (UTC)


 * Keep entries seperate. Perfect fluids are very compressible, in fact they are used as the source for most traditional cosmological models, whose main characteristic is that they expand.



Well, the cosmological models the reader is most likely to have encountered in textbooks are dust solutions, which are perfect fluids with zero pressure. However, dust solutions are also very frequently used to model gravitational collapse, e.g. in the well-known Oppenheimer-Snyder model.

As for the merger, without reviewing I don't know who proposed this or why I thought it was a good idea. In June 2006 my reaction is that there are probably good reasons to have seperate articles on perfect fluids in physics in general and perfect fluid solutions in the sense of exact solutions in general relativity.

Students beware
I completely rewrote the Sept 2005 version of this article and thought I had been monitoring it for bad edits, but apparently not since I missed the comments in the preceding section. I am leaving the WP and am now abandoning this article to its fate.

Just wanted to provide notice that I am only responsible (in part) for the last version I edited; see User:Hillman/Archive. I emphatically do not vouch for anything you might see in more recent versions. I hope for the best, but unfortunately general relativity attracts many cranks, some of whom have been known to make various false claims regarding perfect fluids in gtr. In particular, several active WP editors are involved with fringe science research on alternative cosmologies and may edit this article to slant information in favor of their fringe viewpoint on topics allied to perfect fluids.

Good luck in your search for information, regardless!---CH 02:41, 1 July 2006 (UTC)

Stress-energy tensor section has errors and is redundant
According to B. Schutz's book which is cited in the Dust solution page (which is linked to from this page), the metric tensor is used, not specifically the Minkowski metric, in the calculation of the stress-energy tensor's components. I can add a citation to that source for that, as I believe that book should be considered a reliable source, especially given that it's already in use as one.

I might also clean up that section a little bit, as it's quite redundant and difficult to read at the moment. If anyone has any objections please voice them. OverzealousAutocorrect (talk) 00:24, 2 February 2024 (UTC)