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2023
Journal Article
Titel
Toward a continuum description of lubrication in highly pressurized nanometer-wide constrictions: The importance of accurate slip laws
Abstract
The Reynolds Lubrication Equation (RLE) is widely employed to design sliding contacts in mechanical machinery. While providing an excellent description of the hydrodynamic lubrication regime, friction in boundary lubrication regions is usually considered by empirical laws, since continuum theories are expected to fail for lubricant film heights β0 βͺ 10 nm, especially in highly loaded tribosystems with normal pressures ππ β« 0.1 GPa. Here, the performance of RLEs is validated by molecular dynamics sliding simulations of pressurized (with ππ = 0.2 - 1 GPa) hexadecane in a gold converging-diverging channel with minimum gap heights β0 = 1.4 - 9.7 nm. For ππ β€ 0.4 GPa and β0 β₯ 5 nm, agreement with the RLE only requires accurate constitutive laws for pressure-dependent density and viscosity. An additional non-linear wall slip law relating wall slip velocities to local shear stresses extends the RLEβs validity range to even the most severe loading condition ππ = 1 GPa and β0 = 1.4 nm. Our results demonstrate an innovative route for non-empirical predictive continuum modeling of highly loaded tribological contacts under boundary lubrication conditions.
Author(s)
Project(s)
Effizientes KΓΌhlen, Schmieren und Transportieren β Gekoppelte 1089 mechanische und fluid-dynamische Simulationsmethoden zur Realisierung effizienter 1090 Produktionsprozesse