Dissipation in combined normal and superfluid flows of He II: A unified description

Abstract

We have measured the dissipation associated with superfluid turbulence in circular tubes for combined normal and superfluid flows spanning the $V_n$-$V_s$ plane from pure superflow to thermal counterflow. For relatively small values of $V_n$ the dissipation is consistent with a homogeneous distribution of quantized vortex lines in the superfluid if it is assumed the lines are dragged by the normal-fluid flow. For larger values of $V_n$ this unified description is destroyed by the phenomenon associated with the TI-TII transition in thermal counterflow.