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Vortex in a Pipe / Solutions or approximations?

I want to study a vortex flow in a pipe; in other words helical flow. A couple introductory texts on fluid mechanics (e.g. Shames, Mechanics of Fluids) describe the solution to vortex flow in 2D: ...
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1answer
28 views

Physical intuition for Lamb vector

In many aerodynamical descriptions involving vortex structures (e.g. the Crocco's theorem) there is a useful physical quantity called Lamb vector: $$ \vec{\omega} \times \vec{v} $$ where ...
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Vortex filaments in Stokes flow

Suppose that due to some sort of active process (like a moving boundary or an array of pumping source-sink dipoles) it was possible to create lasting vortex filament at low Reynolds number. While ...
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1answer
39 views

Tornado Vortex Low-pressure Force

If a tornado forms not contacting the ground and then moves over a large flat roof and contacts that surface, producing low pressure above that surface and having normal, higher atmospheric pressure ...
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25 views

Sustained nuclear criticality in liquid vortex

In 1958, chemical operator Cecil Kelley was killed by a nuclear excursion in a mixing tank. A tank intended to reprocess trace amounts of dissolved plutonium-239 accidentally had dramatically more ...
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1answer
43 views

What is actually the characteristic length in fluid dynamics description?

In many fluid-dynamics models and quantities (Reynolds number, Strouhal number... generally various turbulent flow descriptions) there is a parameter (usually $L$ or $\ell$) descripted as ...
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1answer
65 views

What shape is a vortex?

When I see a whirlpool form around the drain in my tub, or see a hurricane on the radar, to my naked eye it looks pretty much circular from above. Is it a perfect circle? An ellipse? If not, ...
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1answer
67 views

Air core Vortex; Physical explanation of the “air Entrainment Hook” at $F_{co}=0.7$

This question was originally asked in the Outlook of this study (page 197)1 $F_{co}$ combined Froude number, [dimensionless], and can be calculated $F_{co}\thickapprox v_D/ \sqrt{gh}$ where $v_D$ is ...
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115 views

Numerical model for a Air core Vortex, why it's still so limited? [closed]

The Question can be Formally presented as follows; How is the Numerical Model (CFD, Navier Stokes) of fluid dynamics for Vortexes at in it's limits? At this Publication from 2013 at page 48 is ...
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62 views

The Optics of the Vortex (in Water): why there is a bright ring also in reversed flow?

This question is closely related to this one; The optics of vortex (in water): why there is a bright ring? In this case "physics girl" gives somehow an plausible explanation, and it's only debatable ...
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1answer
20 views

What is beam confinement?

In the context of the propagation of an electromagnetic wave and optical vortex solitons, I came across the term "beam confinement". Particularly, beam confinement requires the amplitude of the ...
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1answer
57 views

Why superconductor have vortex

Sorry guys I really don't understand the idea of vortex in superconductor, why superconductors type II have vortices ? Thanks in advance!
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1answer
92 views

Physical intuition on vortex sound generation

Whenever a fluid has a nonzero vorticity, it looses some of its energy in a form of sound wave. Formally is this mechanism described by Lighthill's equation or some related model (like e.g. Curle's ...
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44 views

A leaf floating on the surface of water (in $x$-$y$ plane) curl along positive $z$ axis [closed]

A leaf floating on the surface of water (in x-y plane) show that for a very small circular leaf ($\nabla \times \overrightarrow v $) is equal to twice the angular velocity of rotation of the leaf, ...
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1answer
30 views

Why do you feel air moving past you when you walk?

I know that when you walk through the air you form a wake vortex and turbulent air behind and the vortex grows the faster you walk. When I walk past people I almost feel wind that's behind them. So ...
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35 views

Angular momentum transfer in a bottle vortex

A colleague and I were discussing the following fluid mechanics experiment, which most people have probably tried in their kitchen: take a bottle full of water (a 2-litre transparent soda pop bottle ...
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24 views

Formation of vortices in superconductors

So I'm trying to understand how mixed state of a type II superconductor becomes the energetically favourable state. I've been through a simple approximate calculation considering a S-N boundary to ...
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2answers
57 views

Why does a vortex have so much suction power?

A vortex that's on the ground(tornado) can rip tiles off a roof of a house and basically sucks in the roof tiles. On an aircraft that develops vortex lift the vortex sucks in air molecules and reduces ...
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2answers
94 views

Frame dragging in general relativity versus classical vorticity concepts

Can anyone please clarify what one means by a vorticity in Space-Time? I'm aware of the vorticity in Fluid Mechanics. Is it the same vorticity that appears in General Relativity? Is vorticity related ...
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24 views

Dirac equation in the presence of a defect

The 1D Dirac equation in the presence of a defect is described by a position dependent mass term known as a "kink" or "soliton". It is sign changing and tends to a constant at positive and negative ...
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1answer
216 views

How deep can a whirlpool descend?

My question is based around comparing the physics of a tornado against, what I imagine/assume to be the marine equivalent of a tornado, that is a whirlpool located either at sea, in a tidal region or ...
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2answers
332 views

Why does the vortex form in the von Karman Vortex Street?

Why does the vortex form in the von Karman Vortex Street? So far I have this for the reasoning: 'It occurs when a fluid flows around a cylindrical object. The pressure on a fluid particle rises to ...
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1answer
67 views

Does a whirlpool(vortex in water) continue in air(vortex in air),and when does a vortex stop?

First part: The question is both about the continuity of the water vortex(whirlpool) to vortex in air in time and in space. About continuity in time,does the vortex of the water slowly produce a ...
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371 views

The optics of vortex (in water): why there is a bright ring?

This picture is from this YouTube video from "Physics Girl", which shows how you can generate vortices in a swimming pool by using a plate: And there she explains the creation of the shaded circle ...
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1answer
166 views

Can gravitational waves carry momentum, and if so what mass/energy produces it, and is space-time capable of vortex formation?

This question is about gravitational waves postulated by Einstein. Is gravitational radiation a form of mass/energy that can form momentum? If it causes ripples in space-time, would space-time ...
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0answers
42 views

What happens to magnetic $B$-field in a superconductor in the Bean model?

In the Bean model, as we start applying a magnetic field $H$ in the plane of a slab, the $B$-field inside the superconductor decreases linearly from each side, and at a sufficiently high field $H^{*}$ ...
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41 views

Ratio between power of chaotic and regular airflow

Turbulent field is created as a result of an impact of an airjet on an edge (the flow velocity is high enough). The field of velocities have a regular and a chaotic component. What I need is to ...
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2answers
118 views

Destroying currents in superconducting rings by vortex tunneling

Consider a superconducting metal ring in which there is a persisting current $I$. I am interested in the failure of this current to remain "persisting" in the ring, although this will occur at ...
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1answer
32 views

Could a small vortex form off of a large vortex?

Is it possible that a small vortex may branch off of a larger vortex? Note: forgive the elementary drawing, I could not find anything better on the internets.
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0answers
33 views

What if you spin a fluid in one direction at center and at the same time opposite direction at outside?

This question keeps me busy for couple of weeks. To be clear, If I put a fluid into a blender and start it, it will spin in one direction. This will create a small vortex. What if I am able to spin ...
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1answer
134 views

Is it possible to generate one half of a Karman Vortex Street?

The Karman Vortex Street is a type of phenomenon which is generally illustrated by examples in which a long, solid, smooth circular cylinder moves at constant velocity through a fluid. The long axis ...
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1answer
78 views

What does “downshear” mean?

I occasionally read descriptions such as "downshear of the vortex" in meteorological publications. What does this mean?
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3answers
4k views

Emptying a bottle faster by swirl

A moment ago, I was emptying bottles filled with water (2 liters) that are on the terrace of my house. As I did so I remembered something I saw on TV a some time ago (I don't remember when or where or ...
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1answer
208 views

Vorticity versus Viscosity

For a work project I need to revive my aerodynamics knowledge again. Can somebody help me with the distinction between vorticity and viscosity. If a flow vorticity is not equal to zero, the flow is ...
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110 views

Vortex doublet in 2D

I am not from physics background and I am looking for some easy source for learning vortex doublet related theory. Can anyone suggest me something please?
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1answer
186 views

Can one model a spiral galaxy with a similar manifold to one for a whirlpool?

My question is more of a phenomenological question than literal, since the forces involved are very different. When one looks at the distortions (or wrinkles or whatever you wish to call them) in the ...
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0answers
78 views

What is the relationship between the angular speed and the diameter of the eye of a water vortex?

In a water vortex formed in a plastic bottle, what is the relationship between the angular speed of the water and the diameter of the hole in the cap? I would have expected that according to the ...
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0answers
31 views

What is “full clutching flow” in fluid-dynamics with regards venturi design?

As the title says, what is "full clutching flow" in fluid-dynamics with regards venturi design? I came across this reference a few times and can not find any further info on it, I'm currently ...
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2answers
111 views

Could galactic rotation be similar to an irrotational vortex?

Could black holes' near light speed rotation cause galaxies to move like an irrotational vortices?
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1answer
2k views

What is a Physically Accurate Explanation for the Kutta Condition?

Countless arguments between highly intelligent people have been waged (on this very site in fact) as to exactly how lift can be explained in an experimentally and mathematically rigorous way. Taking ...
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1answer
72 views

What is the difference between a vortex ring and a circular line vortex?

Can someone explain the difference between a vortex ring and a circular line vortex? Or are they the same?
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1answer
79 views

What is the physical basis of the $\rho \bf{u} \times \bf{\omega}$ force on a fluid vortex line?

In fluid dynamics, the force density on a vortex line is $\bf{f} = \rho \bf{u} \times \bf{\omega}$. In Faber, Fluid Dynamics for Physicists, ch. 4, this is "derived" by analogy with magnetostatics, ...
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1answer
172 views

What's the corresponding symmetry of enstrophy conservation?

In fluid mechanics, especially 2D turbulence study, people talk about conservation of enstrophy. But I can't really understand enstrophy very well, and what's the corresponding symmetry of enstrophy ...
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1answer
434 views

Could the phenomenon of vortex bursting be exploited to reduce wake turbulence?

One of the classic stories in the annals of aerospace engineering is the development (and subsequent redesign) of the F-18 and its Leading Edge Extensions (LEX) due to fatigue problems, problems that ...
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2answers
1k views

Why do co-rotating vortices coalesce, but not counter-rotating ones?

In studying the aerodynamics of modern aircraft equipped with high-lift devices, I have discovered that quite a number of distinct trailing vortices are present in the immediate wake of an airplane in ...
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1answer
64 views

What is the mechanism of vortex angular acceleration?

When a vortex forms there is a linear motion of a less dense fluid rising through a descending heavier fluid. How does this linear density exchange power the rotation of a vortex? Please note that I ...
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3answers
1k views

Why does the tea in the middle of the cup spin faster when I stir it?

Try this: Make a cup of tea, add sugar, and stir it. Now add some milk, while it's still spinning. What I noticed is that the milk appears to move around a lot quicker in the middle of the cup of ...
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3answers
321 views

Why do tropical cyclones not tear themselves apart?

A tropical cyclone is the generic term for a hurricane, typhoon, or tropical storm. Tropical cyclones derive their energy from evaporation of water at the ocean surface which ultimately recondenses ...
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1answer
630 views

Vortex Air Intake

Why is a vortex air intake in an engine cause the fuel to burn more efficiently within a vehicle. Why is this more efficient.
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2answers
256 views

Does vortex shedding exist along the surface of an object?

Vortex shedding occurs due to the detachment of flow. The typical example is for the oscillating wake behind a cylinder, and has a frequency related to the size of the object. I want to know, if a ...