ToTwo-fluid model explain the complex phenomenology of flowing helium described in the introduction, Landau (1941) and Tisza (1940) independently proposed the so-called two-fluid model, according to which Helium II is considered as a mixture of a normal component (viscous, with non-vanishing entropy) and a superfluid component (with zero viscosity and vanishing entropy) [1–5]. This idea had a double motivation: from the microscopic view, it was based on the Bose–Einstein condensation; from a macroscopic view, it provided a possibility of describing apparently contradictory results, as zero viscosity in narrow channels and normal viscosity in torsional viscometers.