Diffusive Decay of the Vortex Tangle and Kolmogorov turbulence in quantum fluids

TL;DR

This paper explores the decay mechanisms of quantum vortex tangles, proposing a diffusive decay process as an alternative to the traditional Kolmogorov cascade explanation, with implications for understanding quantum turbulence.

Contribution

It introduces a diffusive decay mechanism for vortex tangles in quantum fluids, challenging the prevailing Kolmogorov cascade interpretation of vortex decay at zero temperature.

Findings

Vortex tangle decay can occur via diffusion, not only through small-scale dissipation.

Experimental data can be explained by the diffusive decay mechanism.

The diffusive process offers an alternative perspective on quantum turbulence decay.

Abstract

The idea that chaotic set of quantum vortices can mimic classical turbulence, or at least reproduce many main features, is currently actively being developed. Appreciating significance of the challenging problem of the classical turbulence it can be expressed that the idea to study it in terms of quantized line is indeed very important and may be regarded as a breakthrough. For this reason, this theory should be carefully scrutinized. One of the basic arguments supporting this point of view is the fact that vortex tangle decays at zero temperature, when the apparent mechanism of dissipation (mutual friction) is absent. Since the all possible mechanisms of dissipation of the vortex energy, discussed in the literature, are related to the small scales, it is natural to suggest that the Kolmogorov cascade takes the place with the flow of the energy, just as in the classical turbulence. In a series of recent experiment attenuation of vortex line density was observed and authors attribute this decay to the properties of the Kolmogorov turbulence. In the present work we discuss alternative possibility of decay of the vortex tangle, which is not related to dissipation at small scales. This mechanism is just the diffusive like spreading of the vortex tangle. We discuss a number of the key experiments, considering them both from the point of view of alternative explanation and of the theory of Kolmogorov turbulence in quantum fluids.