The present work deals with the analysis of the incompressible laminar shear driven flow in a channel of which one of the walls carries a macro roughness pattern while the opposite one has a parallel velocity. The problem is discussed from the standpoint of lubrication theory and it is shown that the usual simplified models as the Reynolds or the Stokes equations are not applicable. Numerical results are presented for three types of two dimensional macro-roughness and two versions of a three dimensional one. It is shown that a pressure generation effect occurs with increasing the relative importance of convective inertia. Previous analyses found in the literature discussed only the increase of the shear stress due to the presence of the macro roughness but the lift effect due to the pressure generation has never been enlightened up to now. It is further discussed that, extrapolated to a very large number of macro roughness characterizing a textured surface, this new effect could be added to the other lift generating mechanisms of the lubrication theory. It could thus bring a different light on inertia effects stemming from the use of textured surfaces.

Theoretical Analysis of the Incompressible Laminar Flow in a Macro-Roughness Cell

Elastohydrodynamic (EHD) film thickness measurements using optical interferometry have been made of artificially produced dents and grooves under rolling and sliding conditions. These measurements are compared to stylus traces of the dent and groove profiles to determine the local deformation associated with micro-EHD pressure generation. The surface geometry associated with the dents and grooves is seen to become intimately involved in the lubrication process itself, creating local pressure variations that substantially deform the local surface geometry, particularly under sliding conditions. The rolling results have implications concerning surface initiated fatigue and the sliding results show clearly the EHD surface interactions that must occur prior to scuffing failure. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference in Minneapolis, Minnesota, October 24–26, 1978

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Elastohydrodynamic Film Thickness Measurements of Artificially Produced Surface Dents and Grooves

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Quantitative characterization of micro-topography a bibliography of industrial surface metrology

Elastohydrodynamic film thickness measurements of artificially produced surface dents and grooves. [using optical interferometry

On considere un probleme de passage a la limite a deux petits parametres modelisant l'ecoulement d'un fluide entre deux surfaces rapprochees supposees rugueuses. On etudie d'abord la convergence par la methode de l'energie de la solution du systeme de Stokes tridimensionnel lorsque le rapport λ=η/e est constant (η est lie a l'epaisseur du domaine et e a la periode de la rugosite). En faisant tendre λ vers l'infini (resp. vers zero), on montre que le cas ou l'epaisseur est plus grande (resp. plus petite) que la periode est limite asymptotique du cas intermediaire

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Dah-chen Sun

Papers

First Effects of Stokes Roughness on Hydrodynamic Lubrication

Analysis of the Steady State Characteristics of Gas-Lubricated, Porous Journal Bearings

Stability Analysis of an Externally Pressurized Gas-Lubricated Porous Thrust Bearing

Stability of Gas-Lubricated, Externally Pressurized Porous Journal Bearings

On the Stability of Gas-Lubricated Porous Thrust Bearings