Talk:Vortex

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Picture of a C-17 Globemaster's vortex[edit]

Here's a reference to a stunning photograph of a United States Air Force (USAF) C-17 Globemaster III Military Transport's with vortex/twin tornadoes/wake to consider adding to the article:

ChamorroBible.org, Fagualo (Octubre) 10, 2004, "Manguaeyayon na Palabran Si Yuus - God's Precious Words, with The Photograph of the Day". Photo is in the public domain. Main site URL: http://ChamorroBible.org (referenced as "ChamorroBible.org" or the "Chamorro Bible" WWW site).

http://ChamorroBible.org/gpw/gpw-20041010.htm


On the humorous side see http://forums.fark.com/cgi/fark/comments.pl?IDLink=1160585.

It is certainly a beautiful photograph. However, I don't think it would add anything to the article, as there are two images here already. Those with broadband tend to forget what loading these pages can be like for poor old dial-up users! Graham 00:11, 7 Dec 2004 (UTC)

Hopf fibration[edit]

I was wondering if there are solutions to fluid dynamics equations that "look like" or somehow involve Hopf fibrations? The Hopf fibration is interesting because it resembles, in many ways, a dipole. Its vortex-like structure should also be appearant from the picture; I was wondering if there was a deeper connection, beyond the superficial resemblance. For example, is there a soliton-like solution to eqns of fluid dynamics that resembles the Hopf fibration in some way? Sorry for the "advanced" question, but I am curious. linas 00:57, 2 July 2006 (UTC)

"free surface […] is a parabola"[edit]

I always thought it was a catenary. Isn't it? -- 88.134.21.88 14:36, 5 November 2006 (UTC)

Hmm, well IIRC, the variation in hydrostatic head (proportional to ρg dh/dr), provides the inward acceleration (proportional to ρrω*ω) - so no. Linuxlad 15:06, 5 November 2006 (UTC)

Anyone know why this apparent anomaly?[edit]

a vortex that involves no shear and so does not require a force to maintain, is called 'forced', whereas a 'free' vortex involves shear so would require some force to keep going. Asplace 01:18, 14 April 2007 (UTC)

No. A vortex that involves no shear and so does not require a torque to maintain it is known as a 'free vortex' and velocity is inversely proportional to radius. A vortex that involves shear and requires a torque to maintain it is a 'forced vortex' and velocity is proportional to radius. Dolphin51 (talk) 12:42, 22 December 2008 (UTC)

Confusing examples[edit]

Could someone please clarify these examples, and put them back in the article?

  • Ice stalactites are formed by a rotating column of downward-moving supercooled brine.
  • A small stream of falling water starts rotating immediately on release and does so until the speed of downward movement overcomes the cohesion of surface tension and causes its breakup into spray.

Thanks... --Jorge Stolfi (talk) 06:00, 25 September 2012 (UTC)

The definition doesn't quite fit[edit]

Just to comment--- reading the definition, it doesn't correlate to the photos provided. The current definition listed here states that a vortex is liquid, when the accompanying photo shows a vortex of gas. While I realize that the definition on Wikipedia was probably cut-n-pasted from any one of a half-dozen sites that quote the exact same words, but if you are going to use the image with the airplane, then you must change the definition to reflect this, or get rid of the photo. Thanks. 70.188.169.169 (talk) 06:40, 11 March 2011 (UTC)

The definition, and most of the article, uses the word fluid, not liquid. Fluid is intended to include gases, and a fluid is correctly thought of as either a gas or a liquid.
I agree that the definition looks amateurish. It talks about fluid flow that is spinning and often turbulent. It also talks about closed streamlines. I agree that vortex flow can be described as a flow that is spinning, but I disagree that turbulent is an essential part of vortex flow. I also disagree that closed streamlines are an essential part of vortex flow. For example, when an airfoil is generating lift there is a strong vortex at work (called the bound vortex) but the streamlines around the airfoil are not closed.
My preference would be to define vortex flow as any flow in which the streamlines are curved lines; and a vortex as the flow within a boundary where the circulation around the boundary is non-zero. The popular image of the vortex as a spinning flow with closed streamlines can be described as one excellent example of a vortex, but not the only flow that qualifies as a vortex. However, I don't have a reference that defines the vortex in these terms. Can someone help with a reference? Dolphin (t) 04:12, 12 March 2011 (UTC)

Pictures and descriptions of types of vortex don't match[edit]

The picture of motion in an irrotational vortex matches the description of the rotational vortex, and visa versa. This is because the faster flow in the center as described in the the free vortex section, causes the leaf points to turn away from the center, whereas the constant angular velocity (omega) with radius described in the forced vortex section keeps the leaf points pointing toward the center. Don't know whether the labels on the pictures or the article sections need to be changed.—Preceding unsigned comment added by 76.113.109.18 (talk) 02:21, 9 August 2011

Thanks very much for alerting us to this problem. The problem arose in two edits made on 29 July 2011. I have now rectified it by reverting to the situation that existed immediately prior to 29 July. Dolphin (t) 22:41, 9 August 2011 (UTC)

Hi, I am unhappy with the gif images of rotating vortexes. The text states that the rotation of free vortex speeds up as it approaches the center and the image shows something that is not speeding up at all. The ball closer to the center should be going a little quicker. I propose that I or someone else take a video of stuff suspended in water going down a plughole to better explain what is happening. In the meantime, does anyone have gif editing software so that we can quickly fix the image? Thanks, Brian White Gaiatechnician (talk) 19:30, 8 January 2012 (UTC)

The image of the rotational vortex appears to be correct - it shows the body of fluid rotating like a solid, and the two balls rotating through 360° every time the body of fluid makes one turn. I agree with you that the image of the irrotational vortex is incorrect in that the two balls have the same speed. As you have explained, the ball on the inner circle should have a faster angular velocity and a faster linear velocity than the ball on the outer circle. If the two balls were both on the same circle this problem would disappear. The image of the irrotational vortex is correct in that it shows the two balls having no rotation.
These two images were added by Silver Spoon on 16 Nov 2011. I will alert Silver Spoon to this discussion and he might be able to quickly fix the situation.
If you are volunteering to make a video of objects going down a plughole please go ahead! Dolphin (t) 21:35, 8 January 2012 (UTC)
I see, I could speed up the inner circle, it's no problem to do so :). I suggest 1 turn for the outer equals 2 turns for the inner. Silver Spoon 10:39, 12 January 2012 (UTC)
I've uploaded a new image. When the outer ring makes 1 rotation every subsequent ring makes 1 rotation extra in the same time (that's 2 rotations for the outer ball and 3 rotations for the inner ball in 1 loop of the image. The balls itself don't rotate.) Silver Spoon 11:22, 12 January 2012 (UTC)
That's brilliant! Thanks Silver Spoon. Dolphin (t) 11:34, 12 January 2012 (UTC)

Role of pressure confusing[edit]

The way pressure is treated (and also glossed over) is a bit confusing in this article. Firstly it is stated in the summary that the "the pressure minimum in a free vortex is much lower." That may be a mathematically precise phrase to use, but in lay speak is an ambiguous way to phrase things, since "lower" can be taken to mean "less intense." Secondly it is stated that the visible water condensation in a free air vortex is due to the low pressure. Actually it must be due to low temperature caused by adiabatical cooling of depressurized water vapor, since a low pressure in and of itself without a temperature change would tend to promote vaporization, not inhibit it. It would be nice if an expression of the pressure gradient were explicit for free and forced gas vortexes. (71.233.167.118 (talk) 15:16, 12 August 2012 (UTC))

Thanks for your comments. I have made some changes - see my diff. Do those changes help?
The pressure at the center of a forced vortex can be calculated using Bernoulli's principle and the pressure at some distance from the center. The pressure at the center of a free vortex cannot be calculated because approaching the center of such a vortex the speed increases without bound and is undefined at the center. It is possible to use Bernoulli's principle to calculate the pressure at any point other than the center, and to calculate the rate of change of pressure at any distance from the center. Dolphin (t) 03:29, 13 August 2012 (UTC)

Redundant pictures deleted[edit]

With some regret (since they are pretty), I have removed these pictures. The animated gifs say essentially the same thing but somewhat more clearly. --Jorge Stolfi (talk) 01:57, 25 September 2012 (UTC)

Types of vortex illustrated by the movement of two autumn leaves
Vortex south.png Free vortex east.png Vortex east.png
Reference position in a counter-clockwise vortex. In an irrotational vortex, the leaves preserve their original orientation while moving counter-clockwise. In a rotational vortex, the leaves rotate with the counter-clockwise flow.

Added link to wiktionary, because the plural of vortex is mysterious[edit]

Nuff said. --130.85.194.136 (talk) 19:16, 11 May 2013 (UTC)

animations[edit]

Where are the old animations? I prefer them over the new ones even if the overall presentation is better.Klinfran (talk) 07:38, 6 November 2013 (UTC)