It is assumed that the layer is bonded to a rigid substrate, hence the displacements at the bottom of the layer are fully constrained. A finite length of the layer (100 mm) is included in the analysis and the horizontal displacements are constrained at the ends. The central part of the top surface (spanning 13 mm) has been adopted
as the lubricated part of the boundary, Γl . This choice is somewhat arbitrary and is dictated by two factors. Firstly, the length of Γl must be sufficiently large so that the pressure buildup in the inlet zone is not affected, and the fully-flooded conditions are main- tained. Secondly, it cannot be exceedingly large so that the projected domain Pðγl Þ does not get degenerated at high loading (see, for instance, the deformation pattern in Fig. 5d below). At the ends of the lubricated boundary, the hydrodynamic pressure is prescribed as p ¼ 0.