Conditions for the existence of a counterflow in superfluid helium

We show that in He II a counterflow without any local center-of-mass motion cannot be maintained, except for special symmetries of the flow field (e.g., plane axial or spherical symmetry) and for second-sound waves with small amplitudes. Our considerations are based on assuming const. values of the d. and of the ratio of entropy to normal mass. Hence convection by center-of-mass velocities has to be taken into account for general three-dimensional and in particular for turbulent motions even if the total or the av. local momentum vanishes. [on SciFinder (R)]