Comment on "Superfluid turbulence from quantum Kelvin wave to classical Kolmogorov cascade". [arXiv:0905.0159v1]

TL;DR

This comment clarifies that the observed high-wavenumber power-law in quantum turbulence is an artifact of the energy spectrum definition and not evidence of Kelvin wave cascade, also clarifying the expected cascade intervals.

Contribution

It corrects the interpretation of the energy spectrum in quantum turbulence studies, emphasizing the importance of proper spectral definitions.

Findings

The high-wavenumber $k^{-3}$ spectrum is an artifact, not a Kelvin wave cascade.

Clarification of the wavenumber intervals for Kelvin and Kolmogorov cascades.

Abstract

In this comment we point out that the high wavenumber $k^{-3}$ power-law observed by the PRL, [v. 103, 084501 (2009) by J. Yepez, G. Vahala, L.Vahala and M. Soe, arXiv:0905.0159] is an artifact stemming from the definition of the kinetic energy spectra and is thus not directly related to a Kelvin wave cascade. We also clarify a confusion about the wavenumber intervals on which Kolmogorov and Kelvin wave cascades are expected to take place.