Textured Surface Hydrodynamic Lubrication: Discussion

We discuss on a recently presented theory of textured surface hydrodynamic lubrication (Scaraggi, Phys Rev E, 2012). The model, based on the Bruggeman effective medium approach, allows to analytically evaluate the effects of a generic texture shape, distribution, and area density on the macroscopic hydrodynamic characteristics of the contact, such as friction and supported load. In this study, we apply the cited theory to practical cases, and in particular we derive the flow and shear stress tensors for two limiting conditions, i.e., for isotropic (circular inclusion in isotropic medium) and perfectly anisotropic (infinite slit inclusion) flow conductivities. These results are then used to perform near-optimum design calculations for the simplest case of one- and two-dimensional thrust-bearing geometries. Finally, a comparison with published results is presented and discussed. The developed theory may be a very useful tool in the process of evaluating the lubrication performances of sliding microtextured surfaces and for the near-optimum design of a textured pair, where texturing could be achieved by both physical (e.g., microstructuring) and chemical surface manipulation.