A Multiscale Approach to the Mixed Lubrication Regime: Application to Mechanical Seals

This paper presents a multiscale approach to solve the problem of mixed lubrication in mechanical seals. In fact, the lubricating fluid film developed between the faces of mechanical seals is usually a fraction of a micron in thickness, leading to a mixed lubrication regime. However, over a velocity threshold the fluid film can completely separate the faces because of the hydrodynamic effect due to the surface roughness, even if the surfaces are nominally parallel. To study this phenomenon, a deterministic model is preferable because the stochastic theory based on flow factors is unable to reproduce this effect. Unfortunately, a deterministic approach needs a prohibitive amount of nodes and computation time. This is why a multiscale model is proposed. It is composed of a micro-deterministic model working on a small area coupled with a macro model giving the pressure distribution on a macro-mesh. The results of the multiscale model are compared to those of a pure deterministic model in terms of accuracy and computation time when the area of the macro-cells is varied.