Normal Fluid Eddies in the Thermal Counterflow past a Cylinder

A recent Particle Image Velocimetry (PIV) experiment in He II counterflow around a cylindrical obstacle showed the existence of apparently stationary normal fluid eddies both downstream (at the rear) and upstream (in front) of the cylinder. This rather surprising result does not have an analogue in experimental observations of classical fluid flows. We suggest that a qualitative explanation for the apparent stability of such eddies can be provided entirely from the viewpoint of classical fluid dynamics. We also discuss a possible connection between the emergence of the normal fluid eddies and the polarization of the vortex tangle in superfluid.