We make remarks on Sofos {\it et al.}'s [{\it Phys. Rev. E} 79, 026305 (2009)] paper. The focus is about the monotonicity of the slip length of which it is different from previous similar numerical simulation. We also offer a possible explanation for this.
@article{arxiv.0909.0554,
title = {Comments on "Effects of wall roughness on flow in nanochannels"},
author = {Zotin K. -H. Chu},
journal= {arXiv preprint arXiv:0909.0554},
year = {2009}
}