Similarity in non-rotating and rotating turbulent pipe flows

Published in JFM, 1999 by M. Oberlack.

This study is seriously flawed, including mathematical errors and conclusions that do not match results.

All details and corrections are given in https://arxiv.org/abs/1412.3069. Although this Comment explicitly refers to only the subsequent but equally flawed study of M. Oberlack "A unified approach for symmetries in plane parallel turbulent shear flows" (JFM, 2001), all discussions and corrections can be carried over one-to-one to this preceding 1999 release.

The analysis in both publications is equivalent, except for a changed coordinate system: While the 2001 study uses planar coordinates, the 1999-study makes use of polar coordinates. The equivalence in the symmetry analysis is thus only modulo a coordinate transformation.

In fact, the 2001-publication is the defining study for the 1999 release, which can also be easily seen when comparing the submission dates: The former was submitted to the journal two months earlier (7 Jan. 1997) than the latter one (5 Mar. 1997). This clearly makes the 2001-paper the key study on which the 1999 paper is built upon, that is, since the methodology in the 2001-paper is flawed and all its results are in error, as rigorously proven in https://arxiv.org/abs/1412.3069, then so is the 1999-paper.

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