Two-Dimensional CFD-Analysis of Micro-Patterned Surfaces in Hydrodynamic Lubrication

Sahlin, Fredrik; Glavatskih, Sergei; Almqvist, Torbjo ̈rn; Larsson, Roland

doi:10.1115/1.1828067

Cited by 176 publications

(140 citation statements)

References 7 publications

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“…Studies which compare solutions to Reynolds, Stokes and Navier-Stokes equations for textured surfaces have been conducted by a number of researchers [10][11][12][13][14][15]. For more details see Gao and Hewson [16].…”

Section: Introductionmentioning

confidence: 99%

Two-scale EHL: Three-dimensional topography in tilted-pad bearings

Boer

Hewson

Thompson

et al. 2014

Tribology International

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Derived from the Heterogeneous Multiscale Methods (HMM), a two-scale method is developed for the analysis of Elastohydrodynamic Lubrication (EHL) and micro-EHL in tilted-pad bearings with threedimensional topography. A relationship linking the pressure gradient to mass flow rate is derived and represented in the bearing domain through homogenisation of near-periodic simulations describing the Fluid Structure Interaction (FSI) of topographical features. For the parameters investigated the influence of compressibility and piezoviscosity was found to be more significant than that of non-Newtonian (shear-thinning) behaviour on textured bearing performance. As the size of topography increased twoscale solutions demonstrated that at constant load the coefficient of friction increased and the minimum film thickness decreased over a range of pad lengths and tilt angles.

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Section: Introductionmentioning

confidence: 99%

Two-scale EHL: Three-dimensional topography in tilted-pad bearings

Boer

Hewson

Thompson

et al. 2014

Tribology International

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“…The presence of eddies is of both practical and scientific interest since the onset of recirculating flow can enhance load carrying capacity significantly and reduce frictional drag in, for example, lubricated contacts [8,9], as well as affecting wear characteristics by trapping loose, sub-micron particles [6]. Related examples of where exploration of the effects of local flow structure within laminar shear flow has proved extremely informative include the role played by eddies in industrial roll coaters [10,11,12], eddy formation and the effect of localised disturbances on stagnation lines [13,14], and eddy motions and flow patterns [15,16,17].…”

Section: Introductionmentioning

confidence: 99%

Eddy genesis and manipulation in plane laminar shear flow

et al. 2009

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Eddy formation and presence in a plane laminar shear flow configuration consisting of two infinitely long plates orientated parallel to each other is investigated theoretically. The upper plate, which is planar, drives the flow; the lower one has a sinusoidal profile and is fixed. The governing equations are solved via a full finite element formulation for the general case and semi-analytically at the Stokes flow limit. The effects of varying geometry (involving changes in the mean plate separation or the amplitude and wavelength of the lower plate) and inertia are explored separately. For Stokes flow and varying geometry, excellent agreement between the two methods of solution is found. Of particular interest with regard to the flow structure is the importance of the clearance that exists between the upper plate and the tops of the corrugations forming the lower one. When the clearance is large, an eddy is only present at sufficiently large amplitudes or small wavelengths. 1However, as the plate clearance is reduced, a critical value is found which triggers the formation of an eddy in an otherwise fully attached flow for any finite amplitude and arbitrarily large wavelength. This is a precursor to the primary eddy to be expected in the lid-driven cavity flow which is formed in the limit of zero clearance between the plates.The influence of the flow driving mechanism is assessed by comparison with corresponding solutions for the case of gravity-driven fluid films flowing over an undulating substrate.When inertia is present, the flow generally becomes asymmetrical. However, it is found that for large mean plate separations the flow local to the lower plate becomes effectively decoupled from the inertia dominated overlying flow if the wavelength of the lower plate is sufficiently small. In such cases the local flow retains its symmetry. A local Reynolds number based on the wavelength is shown to be useful in characterising these large-gap flows. As the mean plate separation is reduced, the form of the asymmetry caused by inertia changes, and becomes strongly dependent on the plate separation. For lower plate wavelengths which do not exhibit a kinematically induced secondary eddy, an inertially induced secondary eddy can be created if the mean plate separation is sufficiently small and the global Reynolds number sufficiently large.

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“…For textured samples, there might be additional friction resistance due to the stress concentration at dimple edges. The resulting force balance equation is given by F = F roughness + F film viscous shear + F sliding friction + F plowing friction + F edge stress (6) There are no simple solution to the above two equations because they contain more than one unknowns. However, the net friction reduction or lift force by the textures can be determined at the data points selected if we can estimate most of the frictional resistance components.…”

Section: Determination Of Estimation Of Individual Friction Componentsmentioning

confidence: 99%

“…This section presents individual modules developed for estimating frictional components in Eqs (5) and (6). Since the friction resistance related to roughness and interfacial sliding are proportional to the real area of contact and the plowing friction depends on the degree of plastic deformation, the contact solution module is described first.…”

Section: Determination Of Estimation Of Individual Friction Componentsmentioning

confidence: 99%