Properties of Superfluids
Superfluidity results in some strange phenomena that are not observed in ordinary liquids and gases.
Some superfluids, such as helium-3, creep up the walls of the container, flow over the side, and eventually escape the container. This creeping behavior (film flow) actually does occur in a few normal fluids, such as alcohol and petroleum, but due to surface tension.
Superfluids can pass through the walls of containers that hold liquids and gases.
Stirring a superfluid produces vortices that continue to spin indefinitely.
Turning a container of a superfluid does not disturb its contents. In contrast, if you rotate a cup of coffee, some of the liquid moves with the cup.
A superfluid acts like a mixture of a normal fluid and a superfluid. As the temperature drops, more of the fluid is superfluid and less of it is an ordinary fluid.
Some superfluids display high thermal conductivity.
Compressibility varies. Some superfluids are compressible, while other have low compressibility (e.g., superfluid helium) or no compressibility (superfluid Bose Einstein condensate).
Superfluidity is not associated with superconductivity. For example, superfluid He-3 and He-4 are both electrical insulators.
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