Curvature, slip, and viscosity inHe3−He4mixtures

Abstract

We report vibrating wire viscometer experiments in the concentrated and dilute phase of saturated $^{3}\mathrm{He}\text{\ensuremath{-}}^{4}\mathrm{He}$ mixtures showing that the slip length may become orders of magnitude larger than the mean free path due to specular scattering of the $^{3}\mathrm{He}$ quasiparticles with a $^{4}\mathrm{He}$ coating adsorbed at the surface of the wire. Since the liquid does not almost stick to the surface, the boundary conditions for fluid flow are unusual and not accounted for by the current theory for slip [H. H\o{}jgaard Jensen et al., J. Low Temp. Phys. 41, 473 (1980)]. The experimental results are in excellent agreement with a recent theory for slip [R. Bowley and J. Owers-Bradley, J. Low Temp. Phys. 136, 15 (2004)] which accounts for the effect of the cylindrical geometry and for velocity slip in directions normal as well as tangential to the surface of the wire. We find that our viscosity measurements in the dilute phase resulting from the data analysis based on the recent slip theory are in better agreement with the Fermi liquid theory than previous experimental results.