Fractal surfaces and hydrodynamic lubrication

The effects of surface roughness on hydrodynamic lubrication has been broadly researched for many years as one of the main themes of tribology. Surface roughness is not intrinsically simple; rather, it is of a type that can be understood by conquering complexity. Fractal geometry is a mathematical means for unified treatment of randomness at various scales. In this paper, we use an application example for the fractal surfaces of an inclined slider bearing problem, introduce the most recent studies concerning the behavior of surface asperities under EHL conditions, and consider how best to understand random roughness. The discussion will proceed mainly with where the stationary surface has transverse roughness, i.e. parallel grooves and ridges run at right angles to the direction of motion of the opposing plane.