Spherical thermal counterflow of superfluid He4

Spherically symmetric thermal counterflow of superfluid 4He driven by a central heater is unaffected by shear thanks to the absence of walls. This quantum flow displays a two-fluid behavior and upon increasing drive undergoes a complex process of transition to quantum turbulence that involves formation of normal fluid turbulence above a certain critical threshold, drawing energy from a preexisting random tangle of quantized vortices. Spherically symmetric thermal counterflow can serve as a model flow for cosmological phenomena relating cosmic strings to quantized vortices, for processes occurring in neutron stars, or cosmological structure formation within superfluid models of dark matter.