# Questions tagged [superfluidity]

A flow with no viscosity

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### What happens when you stir a superfluid?

If I stir up some liquid helium in a container with an irregular shape, I'd expect to see a vortex break up into smaller and smaller vortices. Since liquid helium has no viscosity, I would also expect ...
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### Does the isothermal compressibility diverge at the lambda line in Helium-4?

Helium-4 has a normal-superfluid phase transition which corresponds to the lambda line in the P-T diagram. The heat capacity at constant pressure $C_p$ shows a discontinuity when the lambda line is ...
31 views

### Closed form solution of the normal density of a superfluid for the Bogoliubov spectrum

I've been trying to solve the following definite integral $$\int_0^\infty dx\, x^4\, \frac{e^{\sqrt{x^4+2 x^2}/Tp}}{\left(e^{\sqrt{x^4+2 x^2}/Tp}-1\right)^2}\, ,\quad Tp = \frac{T}{Un}$$ This is the ...
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### Closed form solution to normal fluid density integral in the two fluid model [migrated]

I've been trying to solve the following definite integral $$\int_0^\infty dx\, x^4\, \frac{e^{x^2+a}}{\left(e^{x^2+a}-1\right)^2}\quad , \qquad a>0\, .$$ This is the density of the normal part of ...
58 views

### Superfluids in areogel and porous media: why?

Aerogels are materials that are like ~90% or more air. As I understand, the topology of the material (i.e. of that part of the aerogel that is not air) is not such that air is contained into bubbles. ...