Numerical Simulation of the Kurtosis Effect on the EHL Problem

Authors: S. Gao, S. Srirattayawong

Abstract:

In this study, a computational fluid dynamics (CFD) model has been developed for studying the effect of surface roughness profile on the EHL problem. The cylinders contact geometry, meshing and calculation of the conservation of mass and momentum equations are carried out using the commercial software packages ICEMCFD and ANSYS Fluent. The user defined functions (UDFs) for density, viscosity and elastic deformation of the cylinders as the functions of pressure and temperature are defined for the CFD model. Three different surface roughness profiles are created and incorporated into the CFD model. It is found that the developed CFD model can predict the characteristics of fluid flow and heat transfer in the EHL problem, including the main parameters such as pressure distribution, minimal film thickness, viscosity, and density changes. The results obtained show that the pressure profile at the center of the contact area directly relates to the roughness amplitude. A rough surface with kurtosis value of more than 3 has greater influence over the fluctuated shape of pressure distribution than in other cases.

Keywords: CFD, EHL, Kurtosis, Surface roughness.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1100507

References:

[1] O. Reynolds, “On the theory of lubrication and its application to Mr. Beauchamp Tower's experiments, including an experimental determination of the viscosity of olive oil,” Philosophical Transactions of the Royal Society of London, vol. 177, pp. 157-234, 1886.
[2] A. I. Petrusevich, “Fundamental conclusions from the contacthydrodynamic theory of lubrication,” Izv. Akad. Nauk. SSSR (OTN), vol. 2, pp. 209-223, 1951.
[3] D. Dowson and G. R. Higginson, “A numerical solution to the elastohydrodynamic problem,” Journal of Mechanical Engineering Science, vol. 1, pp. 6-15, 1959.
[4] H. Okamura, “A contribution to the numerical analysis of isothermal elastohydrodynamic lubrication,” Proc. 9th Leeds-Lyon Symp. on Tribology, pp. 313-320, 1983.
[5] B. J. Hamrock and D. Dowson, “Isothermal elastohydrodynamic lubrication of point contacts, Part 1- Theoretical formulation. Journal of tribology,” Transactions of the ASME, vol. 98, pp. 223-229, 1976.
[6] A. A. Lubrecht, T. N. W.E., and R. Bosma, “Multigrid, an alternative method of solution for two-dimensional elastohydrodynamically lubricated point contact calculations,” Trans. ASME. Journal of Tribology, vol. 109, pp. 437-443, 1987.
[7] N. Patir and H. S. Cheng, “An Average Flow Model for Determining Effects of Three-Dimensional Roughness on Partial Hydrodynamic Lubrication,” ASME, Journal of Lubrication Technology, vol. 100, pp. 12-17, 1978.
[8] C. H. Venner and W. E. Ten Napel, “Surface Roughness Effects in an EHL Line Contact,” ASME, Journal of Tribology, vol. 114, pp. 616-622, 1992.
[9] T. Almqvist and R. Larsson, “The Navier-Stokes approach for thermal EHL line contact solutions,” Tribology International, vol. 35, pp. 163- 170, 2002.
[10] M. Hartinger, M. L. Dumont, S. Ioannides, D. Gosman, and H. Spikes, “CFD modeling of a thermal and shear-thinning elastohydrodynamic line contact,” Journal of Tribology, vol. 130, pp. 179-180, 2008.
[11] S. Gao and S. Srirattayawong, “CFD Prediction of the Effects of Surface Roughness on Elastohydrodynamic Lubrication under Rolling/Sliding Conditions,” Applied Mechanics and Materials, vol. 184, pp. 86-89, 2012.
[12] K. L. Johnson and J. L. Tevaarwerk, “The shear behaviour of elastohydrodynamic oil films,” Proc. R. Soc. London, vol. 356, pp. 215- 236, 1977.
[13] R. Gohar, Elastohydrodynamics, England: Ellis horwood limited, 1988.
[14] D. Dowson, G. Higginson, and A. Whitaker, “Elasto-hydrodynamic lubrication: a survey of isothermal solutions,” Journal of Mechanical Engineering Science, vol. 4, pp. 121-126, 1962.
[15] A.K. Singhal, M.M. Athavale, L. Huiying, L. Jiang, “Mathematical bases and validation of the full cavitation model,” Journal Fluids Engineering, vol. 124, pp. 617-624, 2002.