LAUSR

The recent claim by Grebenev et al (2017 J. Phys. A: Math. Theor. 50 435502) that the inviscid 2D Lundgren–Monin–Novikov (LMN) equations on a zero-vorticity characteristic naturally would reveal local conformal invariance when only analyzing these by means of a classical Lie-group symmetry approach, is invalid. To note is that within this comment the (possible) existence of conformal invariance in 2D turbulence is not questioned, only the conclusion as given by Grebenev et al and their approach how this invariance was derived is criticized and refuted herein. In fact, the algebraic derivation of conformal invariance of the 2D LMN vorticity equations in Grebenev et al (2017 J. Phys. A: Math. Theor. 50 435502) is flawed. Its correction will reveal a globally constant scaling in the fields, instead of a local one as claimed.