Fine tuning in lubrication

Abstract

The design of lubrication systems which can operate at high temperatures and pressures has until recently been very much a ‘trial-and-error’ affair. The problem is that under these extreme conditions the lubricating oil forms films that are too thin to be measured by conventional optical interferometry – one of the standard methods used to test model systems. What is more, the behaviour of lubricant films thinner than around 15 nm is the very area of rheology least understood by theoreticians and most in need of experimental data. It is at these thicknesses that the intriguing transition between behaviour described by continuum fluid mechanics – elastohydrodynamic lubrication – and that described by detailed molecular dynamics – boundary layer lubrication – occurs.