Hydrodynamics of Oscillating Disks in Viscous Fluids: Viscosities of LiquidsHe3andHe4

Abstract

The viscosities of liquid ${\mathrm{He}}^4$ from the lambda point to 4° K and of liquid ${\mathrm{He}}^3$ near the critical point and from 1.3° K to 2.15° K have been determined by the oscillating disk method. Detailed study of ${\mathrm{He}}^4$ near the lambda point shows a discontinuity in the temperature derivative of the viscosity and provides additional evidence that the He I-He II transition is of the second order. Considerations based upon the temperature dependence of the ${\mathrm{He}}^4$ viscosity above 2.5° K suggest that the zero-point kinetic energy plays an important role in determining the transport properties. The viscosity of liquid ${\mathrm{He}}^3$ rises as the temperature decreases, from a value of 18.7 micropoise at 3.35° K to 26.8 micropoise at 1.3° K. A simple empirical equation describes the ${\mathrm{He}}^3$ data over the entire temperature range.