Coupled dynamics for superfluid $^4$He in the channel

TL;DR

This paper investigates the coupled behavior of normal and superfluid components in superfluid helium-4 within a channel, revealing how their interaction influences flow profiles and properties, especially under varying temperatures.

Contribution

It provides a detailed analysis of the coupled dynamics of superfluid and normal components, highlighting the effects of mutual friction on flow profiles and properties.

Findings

Coupling causes flattening of the normal velocity profile.

Mutual friction strength increases with temperature.

Flow properties are significantly affected by the coupling.

Abstract

We study the coupled dynamics of normal and superfluid components of the superfluid $^4$He in the channel considering the counterflow turbulence with laminar normal component. In particular, we calculated profiles of the normal velocity, the mutual friction, the vortex line density and other flow properties and compared them to the case when the dynamic of the normal component is "frozen". We have found that the coupling between the normal and superfluid components leads to flattening of the normal velocity profile, increasingly more pronounced with temperature, as the mutual friction, and therefore coupling, becomes stronger. The commonly measured flow properties also change when the coupling between two components is taken into account.