  In the paper by Khomenko et al. [Phys. Rev. B \textbf{91}, 180504 (2015)] the
authors, analyzing numerically the steady counterflowing helium in
inhomogeneous channel flow, concluded that the production term $\mathcal{P}$ in
the Vinen equation is proportional to $\left\vert \mathbf{V}_{ns}\right\vert
^{3}\mathcal{L}^{1/2}$ (where $\mathcal{L}$ is vortex line density and
$\mathbf{V}_{ns}$ is the counterflow velocity). In present comment we
demonstrated that the procedure, implemented by the authors includes a number
of questionable steps, such as a decomposition of velocity of line and
interpretation of the flux term. Additionally, the overall strategy -
extracting information on the temporal behavior from the stationary solution
also remains questionable. Because of that the method of determination of the
explicit shape of Vinen equation is very sensitive to the listed elements, the
final conclusion of the authors cannot be considered as unambiguous.
