Heat conduction by liquid helium ii in capillary tubes II. Measurements of the pressure gradient

Abstract

The pressure and temperature gradients accompanying heat flow in liquid helium II have been measured simultaneously. The experiments were made in a glass tube of 107·6 μ diameter and 10·2 cm length between 1·3°k and 1·8°k. Significant deviations from Allen and Reekie's rule were observed end are provisionally attributed to an eddy viscosity, η_e, due to turbulence in the superfluid component. An equation, baaed on dimensional arguments, is proposed for η_e which satisfactorily represents the experimental date available at present.