I'm looking for an explanation for the fountain effect in superfluids using the 'two fluid model'. However the explanations I've come across are not very satisfactory From the NASA website http://cryo.gsfc.nasa.gov/introduction/liquid_helium.html But why does superfluid Helium flow from cool areas to warm areas? Unless I'm missing something that it is not a property of all fluids is it? The wiki article on Helium says But I don't see why the system needs to maintain the same fraction of superfluid helium. Surely at higher temperatures there is a lower equilibrium fraction of superfluid.