Explanation of flow dissipation in 3He-B

We propose an explanation for the large dissipation observed by Eisenstein and Packard(1) in U-tube oscillations of superfluid 3He-B. It turns out that the qualitative change in behavior (compared to superfluid 4He) is simply due to the increased viscosities, which are four orders of magnitude larger in superfluid 3He than in 4He.(2) This means that a dissipation mechanism, not previously discussed (and negligible in 4He), becomes important. The observation does not therefore bring into doubt our basic understanding of the superfluid phases.