Comment on "Turbulent compressible fluid: Renormalization group analysis, scaling regimes, and anomalous scaling of advected scalar fields"

Phys Rev E. 2021 Aug;104(2-2):027101. doi: 10.1103/PhysRevE.104.027101.

Abstract

Recently, asymptotic scaling behavior of the compressible randomly forced Navier-Stokes equation has been analyzed with the use of field-theoretic renormalization group near four dimensions [Phys. Rev. E 95, 033120 (2017)PREHBM2470-004510.1103/PhysRevE.95.033120]. Two infrared stable nontrivial asymptotic scaling patterns have been found and their parameters determined in the one-loop approximation. Here, it is pointed out that the asymptotic scaling behavior predicted in this way may not be realized in physical fluid systems. This is a consequence of restrictions on viscosities imposed by the energy balance equation which the one-loop fixed-point value of the relative viscosity fails to meet.