Roughness effect on the frictional force in boundary lubrication

Abstract
The influence of surface roughness on the frictional force between two walls separated by a thin liquid film is investigated. It is shown that the presence of roughness increases essentially the frictional force in confining systems and can lead to the time dependence of the friction. Both effects are related to the morphology of rough interfaces. A new dependence of the frictional force on the thickness of the liquid film is found.