Modeling the squeezed-thin film using generalized oedometric Reynolds equations

Abstract

The behavior of confined flows at the nanometer scale remains largely unpredictable, especially when hydrodynamic separation is of the same order of magnitude of the surface roughness. Here we propose a continuum mechanics-based model integrating solid deformation, fluid compressibility and solicitation frequency to capture and predict the squeeze of a heterogeneous confined thin film between two nanometer-thin antagonistic adsorbed layers on solid surfaces, in both static and dynamic oscillating situations. Validated by direct confrontation to theoretical and experimental results, this model allowed us to provide physical insights in the squeeze mechanisms, confirming the role of the fluid compressibility at the onset of contact, discussing the influence of the adsorbed layer shear elastic modulus for instance, and defining a viscosity-frequency equivalence. It also permitted to assess the mechanical properties of the nanometer-thin adsorbed layers in both situations, when separated by a fluid film and when in contact.