Large-scale normal fluid circulation in helium superflows

We perform fully coupled numerical simulations of helium II pure superflows in a channel, with vortex-linedensity typical of experiments. Peculiar to our model is the computation of the back-reaction of the superfluidvortex motion on the normal fluid and the presence of solid boundaries.We recover the uniform vortex-line densityexperimentally measured employing second sound resonators and we show that pure superflow in helium II isassociated with a large-scale circulation of the normal fluid which can be detected using existing particle-trackingvisualization techniques.