Oscillations of the Helium II – Vapor Interface during Motion in a Channel of a Relatively Large Diameter

Abstract

The article considers the motion of superfluid helium in a U-shaped cylindrical channel with a diameter significantly larger than the helium capillary constant in the approximation of an inviscid incompressible fluid. When a heat flux is applied near the end-face section of one of the channel elbows, a vapor layer emerges near the heater, and the helium II – vapor interface begins to move. The purpose of the calculation is to determine the interface position as a function of time. The heat transfer in a liquid is described using the semi-empirical Gorter-Mellink theory. The processes in the vapor are analyzed based on the methods of molecular kinetic theory. The influence of the gravity field is studied. The system of equations is reduced to an ordinary second-order differential equation, which is solved numerically. Various process development scenarios depending on the heat flux are obtained. The occurrence of oscillations is described, and the influence of parameters on the oscillation amplitude and frequency is analyzed. In this way, the previously obtained experimental data have been interpreted.