The two-fluid model with superfluid entropy
arXiv:cond-mat/9507038 · doi:10.1007/BF02451645
Abstract
The two-fluid model of liquid helium is generalized to the case that the superfluid fraction has a small entropy content. We present theoretical arguments in favour of such a small superfluid entropy. In the generalized two-fluid model various sound modes of He$\;$II are investigated. In a superleak carrying a persistent current the superfluid entropy leads to a new sound mode which we call sixth sound. The relation between the sixth sound and the superfluid entropy is discussed in detail.
22 pages, latex, published in Nuovo Cimento 16 D (1994) 373