Rayleigh Disk in dc Helium II Counterflow

Abstract

The torque on a Rayleigh disk in dc helium II counterflow produced by a heater has been measured over the range 0.969 K to ${T}_{\ensuremath{\lambda}}$. We find that the response of the disk is approximately the same for normal fluid and superfluid. A torque deficit of \ensuremath{\approx} 50% of that from potential-flow theory appears to be explainable in terms of turbulent, supercritical flow in the channel, rather than anomalous disk behavior. These findings are in contradiction to a number of other studies involving net mass flow relating to the "$\ensuremath{\lambda}$-point anomaly" of Pellam.