Numerical Simulation of the Effects of Three-Dimensional Roughness on Hydrodynamic Lubrication: Correlation Coefficients

Numerical simulations of the lubrication of rough surfaces have been done using the Finite Element Method. Only pure pressure flow conditions have been considered. The correlation coefficient between pressure and height, pressure and height gradients etc. are presented for two different isotropic suifaces. For comparison, one slightly anisotropic surface and one surface with pure transverse roughness have also been investigated. The three-dimensional surface roughnesses have been produced numerically using Finite Impulse Response (FIR) filters and FFT. The only two significant correlations are between the pressure and the height gradient in x-direction and between the height and the pressure gradient in x-direction. The correlation coefficients can be used to apply better boundary conditions when analyzing the lubrication of a rough bearing, and how this can be done has been roughly explained.