Erratum to: Tribol Lett (2015) 58:45 DOI 10.1007/s11249-015-0518-1

The original version of this article unfortunately contained an error in equation. The power of the numerator was incorrect in Eq. (4). The corrected version is given below:

$$ f(\theta ) = \frac{{(1 + \cos \theta )^{1/2} }}{{(1 - \cos \theta )^{1/6} (2 + \cos \theta )^{4/3} }} $$
(4)