Dipartimento di
Ingegneria Meccanica e Aerospaziale

In ordinary systems, friction forces slow down the speed of structures and reduce their lifetime. This is not necessarily the case in superfluid helium. Using a new fully-coupled theoretical description of the mutual friction interaction between superfluid and normal fluid components, here we explain why a bundle of vortex rings moving in superfluid helium at finite temperature travels at constant speed a significant distance, as observed in the laboratory, and in contrast to predictions of previous models describing a quick decay of the vortex bundle.