A theoretical study of a ®nite grooved journal bearing lubricated with couple stress¯uids is made considering both thermal and cavitation effects. On the basis of the Stokes couple stress¯uid model, the modi®ed Reynolds equation and the energy equation are derived and then numerically solved together with the heat conduction equation. The solution to the modi®ed R eynolds equation is determined using the Elrod cavitation algorithm. The effects of couple stress on the performance of a journal bearing are investigated. It is observed that the lubricants with couple stress, compared with N ewtonian lubricants, not only yield an obvious increase in load capacity and decrease in coef®cient of frictio n but also produce a slight increase in the temperature of lubricants and bush and a slight decrease in the side leakage¯ow.

In order to understand the correlation between the connection of surface microstructures and lubrication and seal performances, a novel method to characterize the connectivity of the three-dimensional (3D) surface topography, based on mathematical morphology, is presented. A new concept of surface connectivity index is proposed. Quantitative description of the connectivity of 3D topography in digital space is made by recursive operation of multiscale erosion. The variations of the surface connectivity index with the surface height are approached. The reliability of the surface connectivity measure method is analysed. As a practical application, the connectivity of the 3D topography of a cylinder liner of an engine is evaluated. The results of calculation and analysis indicate that this approach has an explicit signification and reliable arithmetic, and it can effectively describe the connection characteristics of surface structures.