Numerical analysis of combined influences of inter-asperity cavitation and elastic deformation on flow factors

Abstract

Combined influences of inter-asperity cavitation and elastic deformation of rough surfaces on flow factors were investigated based on an extended Reynolds equation for flow factor analyses. The numerical results reveal that when effect of cross-flow of lubricant is not obvious, the pressure flow factor increases, whereas the shear flow factor decreases, for a small ratio of film thickness to roughness, due to influences of inter-asperity cavitation and the elastic deformation of rough surfaces. When the ratio of film thickness to roughness becomes big, however, the influences become weak and can even be negligible. Moreover, the above influences are sensitive to the orientations of rough surfaces. Therefore, combined effects of inter-asperity cavitation and elastic deformation of rough surfaces should be considered in flow factor analyses.

Study on combined influence of inter-asperity cavitation and elastic deformation of non-Gaussian surfaces on flow factors

“…6 that the increment in pressure flow factor is relevantly closer to γ . This trend in variation of the pressure flow factor under non-Gaussian surfaces is similar to Gaussian surfaces in the authors' previous work [15]. …”

“…7. This difference is obvious from variations of the shear flow factor under Gaussian surface circumstances with the cavitation index in the authors' previous work, where the shear flow factor decreases because of inter-asperity cavitation, but continuously increasing φ yields fluctuations in φ s [15]. This difference between shear flow factors from Gaussian and non-Gaussian surfaces emerge from the simulated rough surface characteristics.…”

“…According to the above analyses, the combined influence of inter-asperity cavitation and elastic deformation of non-Gaussian rough surfaces on flow factors will be investigated in the present study as an extension of the authors' previous work [15]. In the investigation, the same assumption in relation with authors' previous research is assumed, i.e.…”

“…10, where asymmetry of cavitation zones with respect to the lines parallel to x or y axes, is due to asperities on a randomly generated non-Gaussian surface, although, the whole computation domain is symmetric. For high h/σ values, say h/σ 3, the shear flow factor values from non-Gaussian surfaces are least affected by the cavitation due to the small variation in cavitated areas as experienced under Gaussian surface circumstances [15]. After the above investigation on effects of interasperity cavitation on shear flow factor, φ s , are made, influences of elastic deformation of non-Gaussian surfaces on the shear flow factor will be analysed.…”

“…Recently, the influence on the flow factors, mainly, on the shear flow factor, was examined by Harp and Salant [13] who employed a new densityrelated factor to account for the reduced fluid density due to the inter-asperity cavitation effect by using Elrod' cavitation algorithm [14]. More recently, the combined effect of inter-asperity cavitation and elastic deformation of Gaussian rough surfaces on the flow factors has been investigated by the authors [15] due to the fact that the inter-asperity cavitation and elastic deformation of rough surfaces can appear simultaneously under certain operation conditions (for the elastic surface processing big roughness amplitude, for example).…”