Talk:Vorticity

message: How is Biot-Savart a part of fluid dynamics?  —Preceding unsigned comment added by 18.218.1.100 (talk) 23:59, 8 September 2007 (UTC)
replies: text:  Used to evaluate flow due to a system of vortices - see say Horseshoe vortex of a wing, or thin-airfoil theory. Bob aka Linuxlad 14:04, 9 September 2007 (UTC)
thread_title:  Biot-Savart? 

message: (William M. Connolley 19:16, 25 Jun 2004 (UTC)
thread_title:  Edit wars and others 

message: The article mentions "vorticity" moving from place to place. Is this related to the conservation of angular momentum? It might be worthwhile mentioning it if so. I suppose that angular momentum density would be equal to the vorticity times the density of the fluid or something.
:There is indeed a close relation between the two ideas, because ω is twice the local angular rotation rate. So the angular momentum of a small spherical blob in the fluid, of moment of inertia I, is (0.5 I ω) (see Batchelor eqn 2.3.12 & 5.2.2). But you'ld need to keep tabs on I, as the fluid distorts, as well as ω. The constancy of the strength of a (small circular) vortex-tube in inviscid flow is essentially a statement of the conservation of the angular momentum within it (see Batchelor, eq 5.3.4). Linuxlad 09:55, 23 February 2006 (UTC)
thread_title:  [[User:Pmurray bigpond.com|Pmurray bigpond.com]] 23:20, 22 February 2006 (UTC) 

message: Somewhat counter-intuitively, an irrotational fluid can have a non-zero angular velocity (e.g. a fluid rotating around an axis with its angular velocity inversely proportional to the distance to the axis has a zero vorticity)
It should probably be azimuthal velocity. For a simple cylindrical rotating case rot V = 1/r*(d(r V_phi)/dr ). When V_phi=1/r then rot V = 0.
I'm not changing the page because I may be wrong but still check this out, pls. 
Best regards, Step.
Yes it's rv=constant in a 'free vortex'. The description of forced and free vortices in vortex uses the term 'tangential velocity' which may be preferable to 'azimuthal' (which suggests angular rather than linear measure). Linuxlad 12:57, 9 March 2006 (UTC)
thread_title:  Misprint or my bug? 

message: In the atmospheric sciences, vorticity is the rotation of air around a vertical axis. In the Northern Hemisphere, vorticity is positive for counter-clockwise (i.e. cyclonic) rotation, and negative for clockwise (i.e. anti-cyclonic) rotation. It is the same in the Southern Hemisphere although the rotational direction differs to that in the Northern Hemisphere.
These sentences seem confusing to me for the Southern Hemisphere consideration. Is vorticity positive for counter-clockwise rotation (anti-cyclonic) or for clockwise (cyclonic) rotation?
--User:ludooohhh 08 October 2007
Done.  Dolphin51 22:32, 13 November 2007 (UTC)
thread_title:  Southern Hemisphere vorticity 

message: Does anyone know of the standard Metric SI units for Vorticity?  This should be mentioned in the article.  --70.48.52.77 (talk) 16:04, 20 October 2008 (UTC)
replies: text: The vorticity of a small parcel of fluid is twice the angular velocity of that small parcel.  Angular velocity can be measured in revolutions per minute but is more commonly measured in radians per second.  The unit of measurement of vorticity in the SI system is also radians per second.  The most significant thing about vorticity is that just about everywhere in a fluid flow field the vorticity is zero, and therefore it requires no units of measurement.  It is only in places such as the boundary layer and in the core of a vortex that vorticity is non-zero.  Dolphin51 (talk) 01:13, 22 October 2008 (UTC)
thread_title:  Vorticity SI Units? 

message: Surely (especially since vortex line redirects here) there ought to be some mention of quantized vortex lines, as seen in superfluids? A.C. Norman (talk) 13:26, 23 July 2009 (UTC)
replies: text: Feel free to write something on quantized vortex lines, especially if you are able to provide an in-line citation to show the source of your information.  You could add some text directly to the article, or place your text on this Discussion page and ask other interested Users for comment.  Dolphin51 (talk) 23:10, 23 July 2009 (UTC)
thread_title:  Quantized vortex lines 

message: I think many people will find it confusing that there is so little scale variation on the figures showing 'absolutre velocity'. Couldn't we remake them so you can actually see some variation on them corresponding to the relative ones?  — Preceding unsigned comment added by 138.37.50.7 (talk) 12:42, 25 February 2013 (UTC)
thread_title:  Absolute and Relative examples misleading 

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thread_title:  External links modified 

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thread_title:  External links modified (January 2018) 

message: On 31 May 2021, edits from 64.189.205.50 changed the expressions "vortex line" to "vorticity line"; and "vortex tube" to "vorticity tube". See the diff.
It is true that some reliable published sources use the expressions vorticity line, and vorticity tube, instead of vortex line, and vortex tube respectively, it is unsound for this Wikipedia article to use the former rather than the latter. The reason I say this is that the concept of a vortex in 2 dimensions, and hence a vortex line in 3 dimensions, is a relatively simple one and should be understood to a wide audience. Anyone who has observed a vortex in the water going down the plug hole, or seen the action of a revolving storm, hurricane, tornado, cyclone etc is familiar with the vortex. Similarly with the concept of the vortex tube.  In "An Introduction to Fluid Dynamics" by George Batchelor the expressions vortex line and vortex tube are used. I will insert a suitable citation into the article.
In contrast, the concept of vorticity is based on another concept - circulation; and is not nearly so simple. For every reader who has some understanding of the vortex, circulation, and the vorticity line, there are many, many others whose understanding doesn't go beyond the vortex and the vortex line in 3 dimensions. Wikipedia is aimed at a general audience, and this article is aimed at readers who ready to think about the vortex and the vortex line, but not yet ready to think about circulation, vorticity and the vorticity line. For this reason I will revert the recent change to "vorticity line" etc and restore the use of "vortex line" and "vortex tube". Dolphin (t) 13:36, 1 June 2021 (UTC)
replies: text: Sounds reasonable. MaxwellMolecule (talk) 18:28, 1 June 2021 (UTC)
thread_title:  Vortex lines vs vorticity lines