Contact of rough surfaces in presence of interfacial fluid flow

International audienceWe present recent results on interplay of surface roughness, mechanical contact and interfacial flow of incompressible fluids. First, we present a technique to determine accurately the true contact area in the framework of a spectral boundary element method used to solve the contact between two rough surfaces. This technique enables us to uncover a subtle link between the so-called Nayak parameter and the rate of the contact area growth with the applied squeezing pressure. Apart from studying the growth of the true contact area, we study how the presence of a fluid (compressible and incompressible) in the contact interface affects the contact characteristics. Moreover, an interplay of solid contact and fluid flow as well as an entrapment of the latter are considered. Two different approaches are used to handle this problem. The first one assumes a one-way weak coupling between the solid deformation and the fluid flow. This approach uses the already mentioned spectral-based boundary element method to solve the non-linear contact problem in the context of infinitesimal deformations, a separate finite element solver is used to solve a viscous laminar fluid flow through the opening in the contact interface, which is governed by Reynolds equation. A self-consistent homogenization technique is adapted and used to link the effective transmissivity with the probability distribution of the gap function. A second approach, assumes a strong coupling between fluid and solid equations. Within this approach both equations are solved simultaneously within a monolithic and strongly coupled framework implemented using the finite element method. Some model problems of fluid entrapment and flow through a wavy channel assuming strong coupling of equations are presented. An engineering study of a fluid flow in contact interface between elasto-plastic solids at roughness scale will be also discussed