Three-dimensional inverse energy transfer induced by vortex reconnections

In low-temperature superfluid helium, viscosity is zero, and vorticity takes the form of discrete, vortex filaments of fixed circulation and atomic thickness. We present numerical evidence of three-dimensional inverse energy transfer from small length scales to large length scales in superfluid turbulence generated by a flow of vortex rings. We argue that the effect arises from the anisotropy of the flow, which favours vortex reconnections of vortex loops of the same polarity, and that it has been indirectly observed in the laboratory. The effect open questions about analogies with related processes in ordinary turbulence.