Talk:Fluid mechanics

Material moved from Wikiproject

I just moved the material from Wikipedia:WikiProject Fluid dynamics/Top draft. There is no sense having a hidden draft in a place other than the article itself. Wikipedia articles are drafts anyway, by definition. COGDEN 03:03, Nov 27, 2004 (UTC)

see /draftMerge Ancheta Wis 09:03, 26 Jan 2005 (UTC)

Macroscopic physical behaviour of fluids

It seems to me that the definition "the study of the macroscopic physical behaviour of fluids" would include thermodynamics (e.g., vapor-liquid equilibria). What is the purpose of using the word "macroscopic" in this definition? And would "mechanical behaviour" be better than "physical behaviour"? YinDW 06:09, 20 Jan 2005 (UTC)

Fluid mechanics or fluid dynamics

I prefer fluid dynamics, and after gaining consensus on what was this article's talk page at the time moved this article there a long time ago, making fluid mechanics a redirect. Someone then decided fluid mechanics needed its own page and wrote something. Then someone else decided that having a page on both mechanics and dynamics was redundant (I agree) and decided they needed to be merged, and merged them here.

Anyway, whatever the history, I think there should be only one page, and that it belongs at Fluid dynamics. I understand that people like the reasoning down from continuum mechanics to solid mechanics/fluid mechanics. However, the term "fluid dynamics" is used much more often these days, both inside and outside the discipline. And solving the disconnect "above" (continuum mechanics as a parent of fluid mechanics) causes disconnects "below" (the subdisciplines are nearly invariably called hydrodynamics and aerodynamics, and you hear "computational fluid dynamics" at least 100 times more often than "computational fluid mechanics"). moink 17:35, 26 Apr 2005 (UTC)

From an engineering point of view, particularly in civil engineering, fluid mechanics includes fluid dynamics (e.g., open channel flows) and fluid statics, viz. hydrostatics (e.g., reservoir and dam construction, ground water engineering).

Chemical and mechanical engineers are less interested in hydrostatics than civil engineers, and I think physicists even less so. As for "computational fluid dynamics", the word "dynamics" emphasizes the nature of the phenomena and applications that are modeled (aerodynamics, fluid transport, convective flow, mixing and transport of fluids), and many of these problems are governed by mathematics that is highly nonlinear, so the solution process can be difficult and expensive. Hydrostatics problems are also solved numerically, such as in fluid-structure interaction problems ("Will the dam hold?"), but these problems are generally linear or more easily linearized and solved using algorithms quite different than those employed in CFD.

As a person with backgrounds in both chemical and mechanical engineering and who has worked professionally developing and using CFD software, I think if there is to be only one entry in Wikipedia, "fluid mechanics" is more appropriate than "fluid dynamics" as it does not exclude hydrostatics. YinDW 22:52, 8 May 2005 (UTC)

Hmmm, you make some good points. I would say the page as it now stands is mostly about fluid dynamics, and I think fluid statics could use its own page. What would you think of making a short fluid mechanics page, maybe with the stuff about its relationship to the continuum mechanics (which I think distracts from the content a little), and two links, one to fluid statics and one to fluid dynamics? They're pretty different topics (e.g. easily linearized vs. significantly non-linear, as you mention) so we could treat them differently. moink 01:40, 9 May 2005 (UTC)

The current content of this page is indeed limited to fluid dynamics, and if we have only a single fluid mechanics page, the fluid dynamics content will still likely dwarf the fluid statics content. I am undecided on having one page or multiple pages, but your proposal to have a short FM page with links to separate FD and FS pages is probably the direction we should go. Maybe the next step is to contruct the outlines for the three separate pages? YinDW 04:08, 9 May 2005 (UTC)

Nah, the wiki way is much bolder than that! Just start moving things around! moink 04:47, 9 May 2005 (UTC)

Guys can we keep the definition and other theory of Fluid mechanics in simple terms? see the criticism here [1]Sasinfo 19:29, 12 May 2007 (UTC)

I'm not sure how it could be put more simply? One problem with any science or maths article is that it requires a certain level of knowledge and intelligence to understand in the first place. Putting things in layman's terms can often lessen accuracy beyond an acceptable level. Mtoreilly 23:52, 15 August 2007 (UTC)

Overview of fluid mechanics table

I have reservations about this table. It doesn't really make any sense to me.

Fluid mechanics	Fluid statics
	#Fluid dynamics	Laminar flow	Newtonian fluids	Ideal fluids	Incompressible flow
					Compressible flow
				Viscous fluids
					Computational fluid dynamics
					Solutions for specific regimes
			Non-Newtonian fluids	Rheology
		Turbulence

I think it's misleading The divisions just don't work that way. There is no simple hierarchy. A problem could easily be incompressible and Non-Newtonian, or compressible and turbulent, or whatever. Fluid statics also has to deal with being incompressible or compressible. A decision of using compressible or incompressible assumptions is separate and nearly orthogonal to the viscid/inviscid distinction, although I guess the laminar/turbulent distinction can only happen once you've decided to use viscosity. Maybe it can be rearranged to make sense, as in viscous/inviscid to the left of both laminar/turbulent, and Newtonian/non-Newtonian, but I'm not convinced that even then trying to do a hierarchy like this makes any sense. moink 17:53, 26 Apr 2005 (UTC)

Material on pressure

I've removed the following from the top of the article:

Pressure:

Fluid Mechanics deals with the density of a substance which is the mass per unit volume.

When an object is submerged in a fluid, the forces, or the pressure, exterted by the fluid onto

the object will always be perpendicular to the object. To find the pressure, we use the

equation $P=F/A$ where F is the magnitude of the normal force and A is the suface

area.

To find the pressure at a specific point, we use thte equation P= Lim SA-->0 dF/dA.

The unit for pressure is N/m^2 which is also equal to 1 Pascal (Pa).

Pressure varies with depth. Pressure in a liquid increses linearly with depth. To take this

into consideration, P= Pknot + pgh. Pascals law says that a change in the pressure applied to an enclosed liquidis transmistted undiminished to eery point of the liquid and to the walls of the container. An example of this would be a liquid in a series of tubled standing up vertically. The liquid would be at the same height in every tube because the pressure remains consistant.

It was added by 69.119.80.248. If anyone thinks some of the material can be added to the article Pressure, go nuts. Melchoir 01:03, 24 December 2005 (UTC)ɳ×

I agree with the removal; it is largely irrelevant to the Fluid Mechanics article, particularly as the first line says "Fluid Mechanics deals with the density of a substance" which is, if not erroneous, at least misleading.

Wikipedia:Science collaboration of the week

Physical oceanography is a current candidate on the Science collaboration. Vote for it if you want to see this article improved. --Fenice 07:18, 8 January 2006 (UTC)

hydraulic losses in parallel pipes

I have read in many books that the loss in energy is the same in two parallel pipes and it is equal to the head loss between the parallel pipes.

Shouldn't the head loss in each of the pipes be added to get the head loss between the parallel pipes? —The preceding unsigned comment was added by 59.89.21.173 (talk) 08:42, 18 March 2007 (UTC).

Fluid physics

The physics of fluids IS NOT fluid mechanics.

The physics of fluids is much larger, a new and quickly developing branch of physics.

The deletion of the article is inappropriate and the redirect incorrect. See and compare:

[2] and [3]

--LidiaFourdraine 07:14, 7 September 2007 (UTC)

Very interesting. See here Hydrodyn., hydromech. merge proposals? Ema--or (talk) 23:53, 18 February 2021 (UTC) more to come...

Did I mention I agree? Ema--or (talk) 20:55, 19 February 2021 (UTC) Made a new talk page for this issue. Ema--or (talk) 21:04, 19 February 2021 (UTC) seems to a trend, these mergers. Ema--or (talk) 23:59, 19 February 2021 (UTC)

WikiProject class rating

This article was automatically assessed because at least one WikiProject had rated the article as start, and the rating on other projects was brought up to start class. BetacommandBot 09:51, 10 November 2007 (UTC)

Proposed Merging

I would like to propose merging this article with fluid dynamics. I know it was proposed before and was rejected because people felt that mechanics also included statics. Thus mechanics should be the top article above dynamics. But lets be honest about this, the article as it is now is nothing but a few equations and basic theory thrown together. In all honesty, I don't see any way to do what seems to have been the consensus other than to essentially copy large portions of the dynamics article and throw in some hydrostatics. It makes far more sense to merge this with dynamics and create a separate statics article. Forget about the terminology and everything, having two articles on the same topic (Fluid mechanics and dynamics are interchangeable in nearly every mechanical engineering school and research institution I have looked at) is counterproductive. Lets merge these and let it expand the dynamics page, which by far outclasses this one. Iron_Engineer (talk) 04:53, 30 June 2009 (UTC)

Fluid Particle

It would improve the article to provide a precise definition of a fluid particle. I actually had difficulty finding this anywhere on the web (finally locating a good definition in "Lectures in Elementary Fluid Dynamics" by J.M. McDonough). Psalm 119:105 (talk) 10:20, 22 June 2013 (UTC)

Please tell us what McDonough's definition says. Dolphin (t) 11:36, 22 June 2013 (UTC)

He begins by discussing the various ways that velocity can be measured at a point to motivate the idea of averaging the velocity in a small region surrounding the point. Its length scale should be large compared to the mean free path, but small compared to length scales characteristic of the problem at hand. He then gives an example of a cube of air, each edge having a length of 1 micron. Under STP conditions, it contains on the order of 10^17 molecules on average (more than enough). Finally, he compares this to another cube of air at a 300 km altitude, in which each side has dimensions of 1 centimeter. In this case, there are too few molecules for averaging, despite its large size. I am paraphrasing; the discussion is on p. 11-13 of the pdf.Psalm 119:105 (talk) 12:45, 25 June 2013 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Fluid mechanics/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Needs a proper introduction, better overview of N-S equations, importance in real world, history, overview of common terms. Tompw 11:39, 5 October 2006 (UTC)

Last edited at 23:39, 19 April 2007 (UTC). Substituted at 15:17, 29 April 2016 (UTC)

Navier-Stokes Equations

I was finding the section on the Navier-Stokes equations to be problematic. The article is pretty sparse, and yet in this section the presentation went straight to the Cauchy form of the equations. I took the latter out put the former in (for incompressible fluids). Not that this solves all the problems this tiny little article has. Comments welcome. Isambard Kingdom (talk) 22:48, 3 September 2016 (UTC)

Newtonian versus non-Newtonian fluids

In viewing the over-all simple nature of this article, I'd like to cut this section. Comments? Isambard Kingdom (talk) 22:52, 3 September 2016 (UTC)

Why Is This Important?

I came to this article hoping to find an explanation for why people studied fluid mechanics, what made it important enough to be a branch of physics. Nothing here on that forest; just trees. DanQuigley 00:20, 10 October 2022 (UTC) — Preceding unsigned comment added by DanQuigley (talk • contribs)