  In the comment I develop a critical analysis of the use of the HVBK method
for the study of three-dimensional turbulent flows of superfluids. The
conception of the vortex bundles forming the structure of quantum turbulence is
controversial and does not justify the use of the HVBK method. In addition,
this conception is counterproductive, because it gives incorrect ideas about
the structure of the vortex tangle as a set of bundles containing parallel
lines. The only type of dynamics of vortex filaments inside these bundles is
possible, namely, Kelvin waves running along the filaments. At the same time,
as shown in numerous numerical simulations, a vortex tangle consists of a set
of entangled vortex loops of different sizes and having a random walk
structure. These loops are subject to large deformations (due to highly
nonlinear dynamics), they reconnect with each other and with the wall, split
and merge, creating a lot of daughter loops. They also bear Kelvin waves on
them, but the latter have little impact.
  I also propose and discuss an alternative variant of study of
three-dimensional turbulent flows, in which the vortex line density $
\mathcal{L}(r,t)$ is not associated with $\nabla \times \mathbf{v}_{s}$, but it
is an independent variable described by a separate equation.
