# Talk:Turbulence

## Confusing Image

This image is confusing and does not help to illustrate what turbulence is. Also see this image's failed candidacy to become featured picture (2006) for more opinions.

I find the "Turbulence.jpg" image (see thumbnail) very confusing, and not at all helpful for the purposes of illustrating what turbulence is. Given it's important position on the page, I believe this image must be clear, unambiguous, and illustrative - characteristics which the current image does not have. The picture is abstract, confusing, and distracting - I spend more time trying to figure out what it is actually a picture of, than I do seeing and appreciating the turbulent nature of the flow pictured.

See Turbulence.jpg's failed 2006 candidacy for featured picture for several individuals agreeing with this assessment of the image. I propose this image be removed, and replaced with one of the proposed alternatives.

I suggest any of the following images... Please vote! If you prefer a different image, just add it to the table.

 Image Votes This is a very nice illustration of a turbulent jet flow, and shows some very distinct characteristics of turbulence. The image shows many eddies, ranging in size from large to small; it shows turbulent fluctuations at various scales; it is an image of a turbulent jet, a canonical flow often used when describing or illustrating turbulence; and it clearly shows the inhomogeneities in the turbulent flow, in contrast to a laminar jet. I think this image is an outstanding illustration of turbulence, and I vote to replace the existing Turbulence.jpg image with this image. (If a better but similar image of a turbulent jet exists, please suggest it, or add it to the table.) --Charlesreid1 (talk) 10:14, 30 October 2010 (UTC) An image illustrating turbulence generation at an extremely large scale. In this image, the Canary Islands off the coast of Africa are causing vortex shedding and large eddy generation. Another image illustrating turbulence generation at an extremely large scale, caused by the Juan Fernandez Islands. Similar to the above image, shows the result of vortex shedding and large eddy generation. (Potentially confusing, since vortex streets are a very particular form of turbulence). This is the existing image. If you wish to keep the existing image, and not change it, please vote for this image.

--Charlesreid1 (talk) 10:14, 30 October 2010 (UTC)

Will go ahead and make the change. Will monitor this thread and update image accordingly. --Charlesreid1 (talk) 08:56, 1 November 2010 (UTC)

## Turbulence during plane trips

Airplane turbulence is also what I was hoping to find in this page. If someone could make a page on how that specifically relates, that'd be great. 24.136.1.115 02:37, 19 November 2006 (UTC)

I think you're looking for Clear air turbulence. --Wjbeaty 12:05, 23 November 2006 (UTC)
No, CAT is one of several forms of turbulence of concern to aviators. There are others; I don't have time to compose an article, but someone might start with the Aircraft Owners & Pilots Association paper at www.aopa.org/asf/publications/sa14.pdf. There are many on-line sources that provide the necessary published references. Moderate turbulence scares passengers; severe turbulence troubles pilots and extreme turbulence breaks airplanes in flight. //Don K. (talk) 17:56, 9 June 2009 (UTC)

## What the...

"The mixing of warm and cold air in the atmosphere by wind, which causes [[clear-hkjhfkjhkjahksjhdfkjhasdjhf hjfahskdjhfakjsdhfjahfjh akjhsfjha kjshd fkjah sdkjhf jh fkajh jfah skfjhaksjdhfalkjshdflkajshd lkjfahsdkjhf akjhsd fjkah kjsdhf jkahksjdhfkjahsdkjhflkajshdfkjshd fl sjdf hakjshd jfhakjsdhflkjahs kjdhf akjshd kjhf akjshdkjhfaksjdh fjkahskjdhfjahsjdhfkjahsjdkhfjakhsdkjhf ajsh djfh ajshd fjkah sjdhf jsh f jdhfjhd hfjdkjsh fhjdkh sj fhaiu ei iu wi ui oiur iuwoi ioue ru i uw i roiwu rieu rowiue oriuw riuw roiu roiu eoriu oweiru oie uroieu riue rue riue wiru eiru eiru ioweur iouweroiueoiruhvhjhjhdjhjh what is bladder? what is bladederhg uy gus dfg sud fug siuf ghf hfahfjhfjhahfhfa fhjd h f ah djfh a fk sdjfh a fjh ds fjhs fka hsd fja dhf

turbulence]] experienced during airplane flight, as well as poor astronomical seeing (the blurring of images seen through the atmosphere.)"

What's all that?

It's called vandalism. It happens. Watchful editors (like yourself) keep an eye out for it and remove it. --Midnightdreary 13:16, 19 June 2007 (UTC)

## References

The references in this article lack on foundations: There's not even a book, and the pdf file is not accessible.

I recommend the reader to refer the following references for further information:

> WHITE, F. M., “Viscous fluid flow”, 2nd ed., McGraw-Hill, N.Y., 1991,
> WILCOX, D. C., “Turbulence modeling for CFD”. 2nd ed. DCW Industries, 1998
> MATHIEU, J., and SCOTT, J, "An Introduction to Turbulent Flow", CUP, 2000
> HOMSY, G.M., ROBERTSON, C.R., & MUNSON, Bruce R., “Multimedia fluid mechanics”. Cambridge University Press, 2000.

WHY NO MENTION OF ROBERT KRAICHNAN?? His obit is in the NY Times yesterday, Feb. 29, 2008. Says he is generally considered the father of modern fluid turbulence theory. He was awarded both the Dirac Medal and the AIP Onsager Prize, among other recognitions. Recent experiments dramatically confirm his theory of turbulence in two-dimensional flow. Unless this is all wrong, someone who understands this field should add some comments about Kraichnan and his work. Also, there is currently no Wikipedia article about him, an unfortunate oversight. Taylour (talk) 15:50, 1 March 2008 (UTC)

## sounds

I took the recording of what I think are turbulence sounds of a plane: [1] The sound quality is pretty low but I thought it might be nice to add it to the article anyways. The thing is: I don't know where to fit it ;-) Could anyone be so kind as to do this? Cheers, --Ludwigo (talk) 18:14, 11 June 2008 (UTC)

Should be added to Clear air turbulence, not here. Also, please make changes yourself. --Charlesreid1 (talk) 19:45, 5 November 2010 (UTC)

## Quotes

I moved the below two quotes to here. They are much too long and trivial for the article lead. These can perhaps be moved to Wikiquote. --Crowsnest (talk) 10:54, 23 April 2009 (UTC)

According to an apocryphal story Werner Heisenberg was asked what he would ask God, given the opportunity. His reply was: "When I meet God, I am going to ask him two questions: Why relativity? And why turbulence? I really believe he will have an answer for the first."[1] A similar witticism has been attributed to Horace Lamb (who had published a noted text book on Hydrodynamics) — his choice being quantum electrodynamics (instead of relativity) and turbulence. Lamb was quoted as saying in a speech to the British Association for the Advancement of Science, "I am an old man now, and when I die and go to heaven there are two matters on which I hope for enlightenment. One is quantum electrodynamics, and the other is the turbulent motion of fluids. And about the former I am rather optimistic." [2]

## Reverted to old version page of 8 March 2009

For the moment, I reverted the page to the situation of 8 March 2008. Styxpaint changed the energy cascade from large to small scale into the reverse, neglecting a century of turbulence research. As well as introducing a strong bias towards two-dimensional turbulence (neglecting vortex stretching which is at the core of 3D turbulence). And this all without verifiable reliable sources (which the article lacks anyway). So until things are sorted out and properly referenced, I reluctantly reverted to this old version. -- Crowsnest (talk) 10:44, 27 April 2009 (UTC)

N.B. To my astonishment there is not even a page or redirect to vortex stretching. -- Crowsnest (talk) 10:48, 27 April 2009 (UTC)

With respect to the energy cascade, I added the following on the user talk page of Styxpaint, see this version:

1. Changing the mainstream ideas on the energy cascade from large scale to small scale into the opposite,
2. The changes seem to originate from a 2D approximation of turbulence in planetary boundary layers, but these limitations are not always mentioned,
3. The lack of references: at Wikipedia's core is verifiability by reliable sources, which means primarily peer-reviewed scientific articles and renowned science books on the subject. The article was already weak at that when you started editing, lacking inline citations for its claims.
I am sure we can work this out, and your help is very much appreciated. You know the literature on the subject of at least 2D turbulence, so you probably can provide the required references. For the rest it is a question of sorting things out and editing. Best regards, Crowsnest (talk) 08:16, 28 April 2009 (UTC)

And got the following reply on my talk page, see this diff:

Dear Crowsnest:
You can find all the references you like about my edits to the turbulence article on my webpage http://maeresearch.ucsd.edu/~cgibson/Documents2007/. I'm not sure how these should be inserted in WikipediaA articles. The standard model is simply wrong.--Styxpaint (talk) 16:51, 1 May 2009 (UTC)

The next step will be to establish to which extend these new views are supported in the scientific community, or whether this is an isolated view (at the moment). -- Crowsnest (talk) 02:57, 8 May 2009 (UTC)

This is clearly a fringe theory. I can't find any material on the page that (a) is published, and (b) gives a justification for the theory that turbulence cascades from small to large scales. In contrast, I can give dozens of references, both in peer-reviewed journals and in published books, that will state otherwise, and will give justification for it. This is WP:OR and doesn't belong on this page. --Charlesreid1 (talk) 20:02, 5 November 2010 (UTC)

## Needs Introduction

This article does not introduce the subject. Does not define "turbulence". It just launches into discussion with Reynolds numbers. This is an encyclopedia article where people who don't know the subject go to learn. I would like to see a fresh article on this important subject. —Preceding unsigned comment added by 67.169.201.107 (talk) 06:04, 7 October 2009 (UTC)

an article you may find here 2

## need clarification

${\displaystyle \mathrm {Total\,\,kinetic\,\,energy} =\int _{0}^{\infty }E(k)\mathrm {d} k}$,and
${\displaystyle {e}\cdot {Volume}=\int _{0}^{\infty }E(k)\mathrm {d} k}$,
• where e, ${\displaystyle specificenergy}$=${\displaystyle {\frac {E\,}{Volume}}}$
• k, main character from man in black — Preceding unsigned comment added by 86.121.67.182 (talk) 19:04, 22 September 2011 (UTC)

## Introduction Re number

There is a sentence "While there is no theorem relating Reynolds number to turbulence, flows with high Reynolds numbers usually become turbulent, while those with low Reynolds numbers usually remain laminar." But The Kolmogorv Theorem (which is on the page too) almost directly (by viscosity) relates the turbulence to Reynolds number. (Mawigator (talk) 09:38, 28 January 2010 (UTC))

I agree with User:Mawigator. Kolmogorv's theory (not theorem) does appear to relate turbulence and laminar flows to Reynolds Number. Dolphin51 (talk) 12:18, 28 January 2010 (UTC)
Disagree - Kolmogorov theory/hypothesis only applies to turbulent flows. The statement User:Mawigator brought up relates to the transition from laminar to turbulent flow as a function of Reynolds number. The transition is not well-characterized by Reynolds number, and doesn't appear to depend strongly on it, since you can potentially have a laminar flow with a higher Reynolds number than a turbulent flow. --Charlesreid1 (talk) 20:13, 5 November 2010 (UTC)

## Quantifying Turbulence

This article seems a little light on how you can actual characterize turbulence in such a way that you can make a comparison. I've seen turbulence intensity used in a few places, but I've go no idea if it's a common and accepted measure. Can any experts weigh in on the issue? Wjousts (talk) 21:58, 19 January 2011 (UTC)

## Chaos theory/bifurcations

Should be there section about bifurcations in Navier-Stokes approach to turbulence? Hopf/period doubling bifurcations, low-dimensional attractive manifold with chaotic attractive set? Serg3d2 (talk) 16:11, 3 May 2011 (UTC)

## Submarine picture

The picture of the submarine should be removed or replaced by something better, since it does not really show a laminar vs turbulent flow, but rather the breaking of the bow wave, which is an entirely different physical phenomenon. For typical speeds of a submarine and the physical properties of water a quick calculation gives that the flow can only be laminar for the first few centimeters from the leading edge of the submarine. This picture promotes a misconception of the physical process. —Preceding unsigned comment added by 91.16.110.16 (talk) 20:30, 6 May 2011 (UTC)

## Dubious

I removed a highly dubious claim about jet contrails - according to one sentence, they don't create turbulence - which seemed on its face to be false. From what I know of chaos and turbulence in fluids this claim does not seem to possibly be true, and since it also has been tagged since May as lacking any citation, it seemed proper to remove it. I initially tagged it as dubious, but decided it would be better to simply remove it and post here on the off chance someone is of a different mind. I think 7 months is plenty of time to give someone to put up a citation - although if that standard were to be applied across wikipedia I think the whole encyclopedia might shrink by a third ! Still, the rules are the rules - and in this case, I think the answer is quite clear.

Spiral5800 (talk) 11:35, 14 December 2011 (UTC)

## False Statement

"This is why turbulence is always rotational and three dimensional"

It is rotational, but there is such a thing as 2D turbulence, however the energy cascade is opposite that of 3D and behaves fundamentally in a very different way.

This has implications on using 2D simplifications for 3D phenomena or vice-versa. Ptrizila (talk) 21:23, 27 March 2015 (UTC)

## Have any errors I made remained?

I had done an edit in March 2012 where I added bullets/asterisks and re-sorted the features. The features were sorted back on October 2013. Did I leave errors on these features, including adding or removing a word that changes definition? TheGGoose (talk) 20:50, 22 November 2015 (UTC)

## Timescales

We can add integral timescales and lengthscales for turbulent motion. This can be linked to the (auto)covariance page for further equations and information. Lyiu (talk) 20:40, 26 April 2017 (UTC)lyiu

## Turbulent diffusivity

Can we add equations on how to calculate turbulent diffusivity? These equations will vary based on the method (i.e. Lagrangian, Eulerian, etc). Lyiu (talk) 20:40, 26 April 2017 (UTC)lyiu

## Assessment comment

The comment(s) below were originally left at Talk:Turbulence/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.

 The references in this article lack on foundations: There's not even a book, and the pdf file is not accessible

Last edited at 22:00, 19 January 2007 (UTC). Substituted at 09:22, 30 April 2016 (UTC)

It didn't mention how should we use velocity profile to calculate the diffusion coefficient of turbulent. We can calculate DT based on the fluctuation of the velocity profile.Jiamingshi (talk) 05:49, 28 April 2017 (UTC)

## Part of Features Section needs reworking and formatting

This part, that currently begins "Orderly flow patterns in what we are taught is the chaos of turbulent flow 1. ..."

And which goes through some points, and ends with a giant paragraph of references, is not an example of an adequately crafted wiki article. — Preceding unsigned comment added by 75.170.94.12 (talk) 16:40, 23 July 2017 (UTC)