Vladislav Yastrebov (Centre des Materiaux, Évry). The role of surface roughness in contact and transport phenomena.

Because of the roughness (inevitably present in most natural and engineering surfaces), when being brought in contact, solids touch  over multidude of separate "islands" forming the true contact area, which in general is considerably smaller than the nominal contact area. The true contact area affects most of interfacial physics: stress state, friction, adhesion, wear, and also transport phenomena across and along the interface. We study how this quantity relates to material and roughness parameters and how it evolves under squeezing pressure [1,2]. In this context, we will discuss some details of generation of synthetic fractal surfaces, their characterization and the interplay of parameters: root mean squared height and slope, Nayak's parameter, Gaussianity, cutoff wavelengths and fractal dimension. In the second part, we will present a study on a fluid flow through the contact interface [3] weakly and strongly coupled with the mechanical contact resolution. A generalized view on leakage regimes and on the percolation limit will be suggested.

[1] V.A. Yastrebov, G. Anciaux, J.F. Molinari, From infinitesimal to full contact between rough surfaces: evolution of the contact area, Int. J. Solids Struct., 52:83-102 (2015)
[2] V.A. Yastrebov, G. Anciaux, J.F Molinari, The role of the roughness spectral breadth in elastic contact of rough surfaces, J. Mech. Phys. Solids, 107:469-493 (2017)
[3] W.B. Dapp, A. Lucke, B.N.J. Persson, M.H. Muser, Self-Affine Elastic Contacts: Percolation and Leakage, Phys Rev Lett, 108:244301 (2012)