Two-way coupled simulation of quantum turbulence and normal-fluid turbulence in superfluid helium-4

We numerically demonstrate the two-way coupled simulation of quantum turbulence and normal-fluid turbulence in superfluid helium-4. In less than 2.17 K, the superfluid helium is composed of an inviscid superfluid component and a viscous normal-fluid component. The velocity circulation of the superfluid component is quantized, and the superfluid component exists as quantized vortex lines. The tangled vortex line is called quantum turbulence. In the externally driven normal-fluid turbulence, the quantized vortex lines are stretched via mutual friction with normal-fluid and reconnect with each other. Eventually, the transition to quantum turbulence occurs. The quantized vortex lines are bundled in the normal-fluid vortex tubes. This is one of the reasons why the superfluid exhibits the K41 energy spectrum.