Questions tagged [vortex]
The vortex tag has no usage guidance.
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Vortex in liquid collects particles in center
At xmas, I had a cup of tea with some debris at the bottom from the leaves. With less than an inch of tea left, I'd shake the cup to get a little vortex going, then stop shaking and watch it spin. ...
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How to show that the Coriolis effect is irrelevant for the whirl/vortex in the sink/bathtub?
There is a common myth that water flowing out from a sink should rotate in direction governed by on which hemisphere we are; this is shown false in many household experiments, but how to show it ...
user68
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Can magnetic fields be redirected and focused at one point?
I know that magnetic fields can be redirected, but... given a situation where you have static magnetic field over a large area, and you want to quickly change the magnetic field strength. Is it ...
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Why there's a whirl when you drain the bathtub?
At first I thought it's because of Coriolis, but then someone told me that at the bathtub scale that's not the predominant force in this phenomenon.
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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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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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How can I understand a Vortex Tube and its efficiency?
A Vortex Tube takes a pressurized input stream, most typically of a gas, and creates two output streams with a temperature differential. Apparently, it has been described as a Maxwell's Demon.
Both ...
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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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Why are superfluid vortex lattices stable?
Both (a) neutral superfluids that are externally rotated, and (b) type-II superconductors (i.e. charged superfluids) under applied magnetic fields between the critical fields $h_{c1}$ and $h_{c2}$, ...
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Why does bathwater make a vortex in the plughole?
When I google for this I just get stuff about whether or not the Coriolis effect makes it go clockwise or anticlockwise, but I don't care which direction it turns in. I want to know why it turns at ...
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What is the theoretical justification for a fluid flow's being irrotational?
I am not a fluid dynamicist, and I really just began thinking about this problem as my curiousity drew me into building an answer for the question What really allows airplanes to fly?.
It is very ...
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When is a flow vortex free?
To solve problems in fluid dynamics one states often the assumption that the flow is vortex free i.e.
$rot(u) = 0$
It is a basic assumption which is needed for potential flow problems etc.. My ...
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Whirlpools and Tornados
This may not be a great question. But whenever you drain water, a small whirlpool happens, obviously. This got me thinking...
Can we model tornados with this effect, would it even be beneficial?
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Derivation of vorticity equation (incompressible flow)
In the following derivation of the vorticity equation, I do not understand how $\nabla \cdot v=0$ implies $\frac{1}{\rho^2}\nabla \rho \times \nabla p=0$.
We start with the Euler equation
$$\frac{\...
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Could galactic rotation be similar to an irrotational vortex?
Could black holes' near light speed rotation cause galaxies to move like an irrotational vortices?
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Isentropic fluid: cross product of gradients is zero, why?
In the vorticity equation we have the baroclinic term of the form: $$\frac{ {\nabla}\rho}{\rho}\times\frac{ {\nabla}{P} }{\rho}.$$
Why does it go to zero for isentropic flow?
I understand that, if the ...
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Why does my tea periodically alternate its rotational speed after stirring? (Link to video below)
I noticed that after stirring, a bubble in the centre of my mug of tea changed the speed it was rotating at periodically. Speeding up, then slowing down, then speeding up again, etc. Almost like when ...
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Why do chimneys have these spiral "wings"?
While walking around I noticed something very peculiar. Many chimneys had spiral "wings", while others didn't. I came up with two possibilities:
The wind circles around the chimney upwards which ...
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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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Can vorticity be destroyed?
I have a professor that is fond of saying that vorticity cannot be destroyed. I see how this is true for inviscid flows, but is this also true for viscous flow? The vorticity equation is shown below ...
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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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Why water in the sink follow a curved path?
When you fill the sink with water and then allow the water to be drained, the water forms a vortex.. And then it starts to follow a curved path downwards by effects of gravity.
Why this phenomena ...
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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 ...
user81619
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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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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}
$$
where $\vec{\...
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Vortex anti-vortex?
i'm studying Kosterlitz THouless transition and i have a doubt: what is a vortex anti-vortex configuration?
Is this thing?
or this one
I think that they are quite different !
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What role do quantized vortices play from the Superfluid model in Superfluid Vacuum Theory?
When rotating a superfluid (such as $^{4}$He) below its critical temperature, sometimes quantized vortices pop up, depending how fast one rotates this superfluid. In the SVT model, they propose that ...
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Vortex in superfluid?
I'm studying superfluid helium 4. I have studied that the superfluid has a velocity :
$ \vec{v}_s = \frac{\hbar}{m} \vec{\nabla} \varphi(\vec{r}) $ $\rightarrow$ $ \nabla \times \vec{v}_s = 0 $.
(...
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Cascade vs Inverse Cascade: Energy flow in 2D and 3D turbulence
We know that vortices tend to coalesce in 2D(inverse cascade) as opposed to 3D where they 'break down' into smaller vortices(cascade) ie. energy flows fro larger to smaller scales in 3D and opposite ...
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Why is the eye of a cyclone a forced vortex?
As far as I understand, a forced vortex has a velocity profile $u \propto r$ ($r$ is radial distance from centre of vortex), concluding at some outer boundary $r=R$ to avoid fluid particles ...
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How do the Navier-Stokes equations predict vortex creation in a vorticity-free fluid?
For this question I was looking at the Navier-Stokes equations after you get the curl, this gives you the equation:
$$\frac{\partial \vec{\Omega}}{\partial t}-\nabla \times (\vec{v} \times \vec{\...
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Nomenclature clarification concerning solitons
My experience with solitons is restricted to the classical setting, namely solutions to the quartic interaction $\phi^4$, the Sine-Gordon equation, and Korteweg–de Vries equations. I was explicit to ...
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The relationship between height of water and the rotational speed inside a cup
When I stir the water inside a cup with a speed $v$ ( using a stick), I find that a vortex will be formed inside the cup, with the middle part of the water at the lowest point ( with the height $h_0$),...
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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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vortex anti-vortex configuration to ground state [closed]
i'm studying kosterlitz transition. I'm reading this:
https://assets.nobelprize.org/uploads/2018/06/advanced-physicsprize2016-1.pdf?_ga=2.51324009.1302372948.1538119052-1605759177.1538119052
Now ...
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What causes a whirlpool to form in a bathtub? [duplicate]
I mean, when you have a full bathtub and then let it empty, under what conditions does a whirlpool form?
Could we devise an experiment and measure this effect? When it comes to fluids, I don't know ...
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How do the vortices in vortex-induced vibrations (VIV) form?
I am currently doing a research project on the topic of the Vortex Bladeless technology in a technical college course. I have been researching VIV and the intuition behind this, but I am still ...
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Explanation for the next steps of chaplygin dipole
this post is the Chaplygin dipole, it's an interesting issue.
Can someone explain me these steps in other words please? any Explanation of any step will help me, I hope that together I will ...
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When two opposing vortexes combine to form a dipole vortex, why does it always move in the same direction?
AS you know, when two opposing vortexes combine to form a dipole vortex, it always move in the same direction as shown with red arrow in figure below. I wonder, why? is there a equation for this ...
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Metric of a rotating Cosmic String
I searched on the internet superficially but I couldn't find it.
Is there any reference that find the solution to Einstein's Field Equations for a rotating Cosmic String?
Personally haven't got the ...
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Energy of vortex-antivortex pair
I am given the following field in 2d:
$$\theta(\mathbf{x}) = \phi(\mathbf{x}-\mathbf{x}_1) - \phi(\mathbf{x}-\mathbf{x}_2),$$
where $\mathbf{x}_1,\mathbf{x}_2$ are the position of the vortex and ...
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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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