Parameters for Roughness Pattern and Directionality

The average flow model is widely used on the derivations of average Reynolds type equation.There are arguments on the use of Peklenik number ( ^P ), or Bhushan number ( ^B ). In this paper, the orientation angle ( _r ) of the representative asperities (the pattern directionality) as well as the Peklenik number defined in principal directions () is utilized as the parameters to define the texture of surface roughness. An experimental procedure based on the least square method is then proposed to identify the two parameters ( _r and ). The present procedure avoids the above argument on distinguishing the isotropic asperity with the anisotropic asperity oriented with 45°. Only one additional parameter ( _r ) is needed.