A flow with no viscosity
Superfluidity refers to a flow with no viscous dissipation. It is an ideal inviscid flow mathematically described by the Euler's momentum equation.
Questions tagged [superfluidity]
242 questions
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Will a propeller work in a superfluid?
Will a propeller work in a superfluid? Opinions differ.
JDługosz
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Why aren't all quantum systems superfluids
Simply I was just wandering why aren't all quantum systems (F-D and BE condensates) superfluids at low temp like He 3 and 4?
user21119
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What causes Superfluidity?
Superfluidity is the frictionless flow and other exotic behavior observed in liquid helium at temperatures near absolute zero. The unusual behavior arises from quantum mechanical effects.
What are these "quantum mechanical effects"?
Hammar
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Intuitive explanation for superfluidity?
I know that superfluidity is caused by the fluid having zero viscosity. This only happens at very low temperature, so the fluid (e.g. Helium-4) is a Bose-Einstein condensate.
I also know that in a Bose-Einstein condensate all the particles are in…
SuperCiocia
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How does superfluidity not break the conservation of energy?
A superfluid has a property that makes it creep up the walls of its container and escape it until it's empty.
How is it possible that the fluid performs work (against the force of gravity)? I can imagine setting it up so that after dripping to the…
Ruslan Oblov
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Can the Superfluid Rollin effect be used as a perpetual motion machine to extract energy from?
Superfluids such as liquid helium cooled below the lambda point exhibit the Rollin effect where a thin film climbs the walls of the vessel. This still and video from the 1950s shows the effect, where drips of liquid helium form below a cup of…
roblev
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Microscopic Theory of superfluidity
In comparison with superconductivity what is the microscopic theory of superfluidity? Who has done it?
richard
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Do superfluids lack inertia and/or don't exist with a finite speed of sound?
I've been reading a few things on other sources about superfluids and what kind of propulsion would work in them. Supposedly a propeller won't work in a superfluid, but I'm having a hard time understanding why.
As the propeller spins, it pushes…
Shufflepants
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What is the equation for the elementary-excitation spectrum of superfluid heluim over whole momentum space?
I have a simple question. What is the equation for the elementary-excitation spectrum of superfluid helium over whole momentum space, not just near the origin (i.e., phonon excitations $\epsilon=cp$) or near the minimum around $p_0$ (i.e., roton…
Farokh
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How long to drain superfluid from a container with a small hole in the bottom?
The most naive way of thinking would suggest that because there is no viscosity it drains as fast as if you turned the container upside down and let it fall out. However, assuming the hole is smaller in diameter than the container that cannot happen…
user56903
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How two prove the second sound velocity is $1/\sqrt{3}$ times than the first sound
From Landau two hydrodynamics model in superfluid, we have the result
$c_1^2=\frac{\partial P}{\partial \rho}|_T$ and $c_2^2=\frac{\rho_s s^2 T}{\rho_n c}$.
In the zero temperature limit, how to relate those two quantities, to get the conclusion…
Simon
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Why don't we use liquid helium superfluids for infinite clean energy?
Liquid helium, at a low enough temperature, becomes a superfluid. This would mean that if we stirred it, it would keep spinning forever. Surely this means we could use a small amount of liquid helium to generate infinite energy?
I understand that it…
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Do superfluids have zero viscosity?
The Wikipedia definition of a super fluid is:
Superfluidity is a state of matter in which the matter behaves like a fluid with zero viscosity
As a fluid dynamics guy, I have a hard time imagining a zero viscosity fluid. Does superfluids have near…
solalito
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