In a recently accepted paper of M. Ayub, H. Zaman and M. Ahmad [Cent. Eur. J. Phys. 8, 135 (2010)] the authors claim that the governing similarity equations of Vajravelu and Roper [Int. J. Nonlin. Mech. 34, 1031 (1999)] are incorrect; without any justification, the authors Ayub et al. simply mention that the equation is “found to be incorrect in the literature” (though no reference supporting this assertion is provided in the citations). We show that this assertion of Ayub et al. is wrong, and that the similarity equation of Vajravelu and Roper is indeed correct.
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