|WikiProject Aviation||(Rated C-class)|
|WikiProject Physics / Fluid Dynamics||(Rated C-class, Mid-importance)|
- 1 Mohyi Labs Simplified Vortex Explanation
- 2 Picture of a C-17 Globemaster's vortex
- 3 Hopf fibration
- 4 "free surface […] is a parabola"
- 5 Anyone know why this apparent anomaly?
- 6 Confusing examples
- 7 The definition doesn't quite fit
- 8 Pictures and descriptions of types of vortex don't match
- 9 Role of pressure confusing
- 10 Redundant pictures deleted
- 11 Added link to wiktionary, because the plural of vortex is mysterious
- 12 animations
- 13 Rotational profile
Mohyi Labs Simplified Vortex Explanation
(I'm the inventor of ducted counter vortex radial impeller technology (The Bladeless Drone) and I formulated a more complete explanation of the vortex process for a post I made for climate engineering. Feel free to update the explaination page with the updated explaination and contact me at John@MohyiLabs.Com if you have any questions -John Mohyi)
Climate Engineering: Tornados & Hurricanes
Intro & Disclaimer: After researching propulsion in depth, it occurred to me that my understanding of flows for aerospace applications could be applied to natural systems. Below is an explanation of the still poorly understood phenomena of Tornados & Hurricanes consistent within the framework I developed for an advanced propulsion system my team and I have been designing. The explanation below has not been peer reviewed nor has it been subjected to rigorous scientific testing. The explanation below is subject to change, and both support and criticism from experts in the field are welcome as this is meant to spark a conversation. You can also contact me directly at John@MohyiLabs.com or follow Mohyi Labs on Facebook Here.
Mohyi Principle: If there is one fundamental truth about the universe, it is that the universe is always seeking balance. Every particle, equation, and person is bound by this fundamental principle, and to understand it is to be a master of fate.
Tornados & Hurricanes: Gravity is the primary driving force behind Tornados and Hurricanes. It acts more strongly on denser particles pulling them closer to the center of gravity. Contrary to popular belief, hot air does not rise; rather it is displaced by the colder/denser air that gravity acts upon more strongly. This is the same phenomenon at work when oil and water separate into distinct layers. Gravity attracts the relatively denser water more than the relatively less dense oil. In the process, the water forces the oil to the top. This process in conjunction with the rotation of the earth and thermal expansion/contraction causes wind. The sources of thermal energy are both the sun and the earth itself.
The Vortex begins to form when the denser layer above, relative to gravitational pull, collapses at its weakest point into the less dense layer below, which is usually the center, and the downward momentum has an additive effect. This collapse will take on a concave geometry causing the pressure/density to drop at the center generating a vacuum force as it falls toward the center of gravity.
Every medium is constantly seeking balance or equilibrium. A flow is induced when the balance has tilted. A medium of higher density or concentration relative to its surroundings will always seek a lower state of energy by balancing itself with its environment. A flow in essence is simply an expansion. The expansion, though it expands in all directions simultaneously, will be observed as moving more in the direction of least resistance thus resembling a flow. Equal amounts of energy though are expended in all directions.
The vacuum pressure generated by the collapse of the upper layer into the lower layer will induce a flow from not only above, but from the sides of the vacuum as well. Because of conservation of angular momentum, as the flow converges toward the center of the vacuum it will rotate faster. The vortex will stabilize when the outward rotational force, relative to the center of the vacuum, is in equilibrium with the inward vacuum pressure force within the vortex. Since gravity attracts atoms more strongly closer to the surface of the earth, the gradual increase in the atmospheric pressure gives the vorticity its cone like geometry.
Practical Value: The practical value of this model its predictive power, which is a precursor to controlling and harnessing this natural phenomenon. In essence, the power to engage in climate engineering. A few approaches are available some more practical than others:
1) By decreasing the vacuum pressure at the center of the vortex, the vortex equilibrium would expand decreasing the rotation speed resulting from conservation of angular momentum. The most practical method using this approach is to increase the internal pressure via thermal expansion. This may be achieved by focusing a powerful laser at the center of the vortex, or by the use of explosives. This method would only decrease the rotational speed and provide only temporary relief unless the thermal transfer is sustained.
2) By decreasing the density of the upper layer via thermal expansion it is possible to stop a tornado or hurricane before it starts or at least decrease its intensity. This may be achieved by focusing a laser on the clouds or seeding them with an exothermic chemical. This would decrease the density and reduce the gravitational pull. This method may be counterproductive in the long run since the thermal energy will eventually disperse increasing the density.
3) By increasing the density of the upper layer past its collapsing threshold preemptively, it may be possible to prevent or reduce the size of a tornado or hurricane to tolerable levels. A process known as Cloud Seeding is a common practice in China and is used to increase rainfall. By seeding clouds with either silver iodide or dry ice we can fight hurricanes and tornados similar to the way we fight forest fires. (Note: Never seed the central region of an active tornado or hurricane with a cooling agent. That would increase the density and likely exacerbate the problem. You may be able to seed the periphery though.)
4) By building a tower that reaches into the clouds, it is possible to induce a controlled collapse of the denser atmosphere. Once the downward flow generates enough momentum, the gravitational potential energy can be converted into electricity similar to a dam.
Conclusion: Climate Engineering is the sensible response to climate change. Both natural and manmade weather fluctuations are a real concern and we have the capability today to respond to these threats. — Preceding unsigned comment added by 2601:40F:401:180E:A8B8:34A1:D36B:FDAD (talk) 22:16, 4 February 2017 (UTC)
Picture of a C-17 Globemaster's vortex
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).
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)
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"
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?
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)
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.
The definition doesn't quite fit
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. 22.214.171.124 (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
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 126.96.36.199 (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)
- 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)
Actually, the vortex is still not irrotational. Now, the angular velocity is proportional to 6 - r, where r is the number of the ring from the center, but for it to be irrotational the angular velocity should be proportional to r-2 (compare with File:Vorticity Figure 02 a-m.gif). It's a nice illustration though. —Kri (talk) 14:35, 26 August 2014 (UTC)
- I agree that the illustration currently gives an incorrect rotation profile, with the velocity shown being a straight-line function of radius. Though Kri, I think it is meant to be proportional to r–1, surely? I think we really need to insert formulae for the illustrations, with ω = ∇ × v, with v = k(−y, x) and v = kr−2(−y, x) respectively. —Quondum 15:18, 27 August 2014 (UTC)
Role of pressure confusing
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. (188.8.131.52 (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
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)
I think this has to be revised: "If the fluid rotates like a rigid body – that is, if v increases proportionally to r – a tiny ball carried by the flow would also rotate about its center as if it were part of that rigid body. In this case, \vec \omega is the same everywhere: its direction is parallel to the spin axis, and its magnitude is twice the angular velocity of the whole fluid."
It should be the same angular velocity (from current view of picture, i.e.: tidally locked), not twice, unless I misunderstand. I also have some doubt about equations and how they have been derived and it would be recommended to refer either to a basic proof or to a reference handbook.--Almuhammedi (talk) 18:36, 7 August 2014 (UTC)
- In the setup of the scenario, the fluid has a specified velocity. The field of fluid velocities therefore has a curl. Conceptually, think about the force exerted on the side of the tennis-ball closest to the center of the vortex (in slower moving fluid), and on the far side (in faster moving fluid). Assuming ideal fluids, and assuming force is proportional to the velocity of the fluid, there is a differential force separated by the diameter of the ball - i.e., a torque. Conceptually, at least, the ball is expected to start spinning because of this torque. I'd have to work out the math to see if the net result of this effect on the entire tennis ball yields exactly twice the angular rotation rate of the fluid, but conceptually this seems correct. To address that analytically, we'll need to review curl (mathematics) and set up some equations for the special case of rotational velocity proportional to radius. Or, we could find and cite a book that works this problem out. It sounds like a common homework problem. Nimur (talk) 14:05, 9 August 2014 (UTC)
- The quoted statement is self-contradictory, and has nothing to do with forces (it says "as if it were part of that rigid body"). But even with viscous forces due to relative flow etc., the angular velocity of any (neutrally buoyant) body carried along with the flow would settle to the same angular velocity as the fluid exhibits. The formula used for vorticity below the figure is incorrect. —Quondum 21:52, 9 August 2014 (UTC)
It seems I have introduced an error into the definition of vorticity, and hence removed a factor of 2 that should have been there. Vorticity is not defined as the rate of rotation of a small element, e.g. a ball, but as the curl of the flow; this happens to be twice the rotation rate of the fluid element or small ball. I was misled by what was a formula that I removed, so I'll re-introduce the factor. —Quondum 04:12, 28 August 2014 (UTC)