# Why are superfluids thermodynamically possible?

I was reading about superfluids and how they can flow without loss of any kinetic energy over time, specifically they can form vortices that rotate indefinitely. However I do not understand why this is possible as surely the outside of a vortex is moving faster so particles over there have a greater kinetic energy than those closer to the centre so why is there no transfer of kinetic energy over time (say from collisions between particles) until all the particles have the same kinetic energy and the vortex just dissipates away?

Speed of superfluid is the gradient of the phase of wavefunction. Vortices in superfluid are irrotational, i.e. speed vanishes as $\propto 1/r$. Their vorticity (curl of velocity) is zero, except the very center of the vortex (the latter is not strict).