Multi‐linearity algorithm for wall slip in two‐dimensional gap flow

Ma, G. J.; Wu, Chengwei; Zhou, P.

doi:10.1002/nme.1848

Cited by 21 publications

(16 citation statements)

References 31 publications

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“…As shown in Fig. 7, all the film thicknesses were located in the region bounded by the two theoretical curves, indicating that critical shear stress decreases (i.e., a reduction in adhesion strength) with the drop of film thickness [28,29]. As shown in Fig.…”

Section: Resultsmentioning

confidence: 69%

Identifying the optimal interfacial parameter correlated with hydrodynamic lubrication

2016

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Abstract:The effects of boundary (liquid/solid) slip on hydrodynamics are well recognized. However, it is extremely difficult to quantify in-situ boundary slip in a lubrication contact. Therefore, an effective interfacial parameter that is well correlated with the lubrication effect is of practical significance. This paper presents an examination of common interfacial parameters, including surface tension, contact angle, contact angle hysteresis, and a recently proposed spreading parameter. Specimen surfaces of different hydro/oleophobicity were prepared and characterized using the aforementioned interfacial parameters. These samples were further used as bearing surfaces in hydrodynamic lubrication tests. The correlations of these parameters with the measured lubricating film thickness were examined and compared. The key parameter closely related to the hydrodynamic effect was identified.

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Section: Resultsmentioning

confidence: 69%

Identifying the optimal interfacial parameter correlated with hydrodynamic lubrication

2016

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“…Afterwards Li and co-workers coupled other effects such as the (i) flow rheology [17] and (ii) surface roughness [18] to anisotropic boundary slip to more accurately evaluate the performance of journal bearings. Ma and co-workers [19,20] have proposed an extension of the Tresca slip-model for the analysis of twodimensional journal bearings. They assumed a polygonal approximation of the theoretical slip-limit circle and identified suitable complementarity variables to solve the slip problem adopting quadratic programming techniques.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…While our mass-conserving cavitation algorithm has already been demonstrated to be able to simulate these cases, some modifications need to be implemented to predict the slippage in two dimensions, see Ref. 20 A similar procedure can be followed for the y-direction. By substituting z = h in Equation A.4, the velocity of the fluid layer in contact with the upper slipping surface in the x-direction, U s , can be obtained:…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Interplay between wall slip and cavitation: A complementary variable approach

Biancofiore

Giacopini

Dini

2019

Tribology International

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In this work a stable and reliable numerical model based on complementary variables is developed to study lubricated contacts characterised by slip at one or both surfaces and in the presence of cavitation. This model can be used to predict surface behaviour when cavitation induced by e.g. the presence of surface texture, slip, or a combination of the two is encountered, with varying surface parameters. For this purpose, two different algorithms are coupled to predict the formation of cavitation, through a mass-conserving formulation, and the presence of slip at the wall. The possible slippage is described by a limiting shear criterion formulated using a Tresca model. To show the flexibility of our model, several bearing geometries have been analysed, such as a twin parabolic slider, a cosine profile used to mimic a bearing, and a pocketed slider bearing employed to study the effect of surface texture. We observe that the lubrication performance (i.e. low friction coefficient) can be improved by using materials that promote slippage at the moving wall. The location of the slippage region can be optimised to find the lowest value of friction coefficient. Our theoretical developments and numerical implementation are shown to produce useful guidelines to improve and optimise the design of textured superoleophobic surfaces in the presence of lubricated contacts.

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“…Moreover, they analyzed the load-carrying capacity, friction and other lubrication characteristics of infinite-width bearings. Ma et al (2007a, 2007b) extended the quadratic programming algorithm to the solution of two-dimensional surface slip and found that the inclusion of a slip surface could distinctly improve the hydrodynamic load-carrying capacity.…”

Section: Introductionmentioning

confidence: 99%

Optimal design of the slip–texture on a journal-bearing surface

Jin

Chen

et al. 2020

ILT

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Purpose This work aims to explore the combined effects of boundary slip and texturing on hydrodynamic journal bearings and identifies optimized slip and texture patterns to improve the performance of journal bearings. Design/methodology/approach The quadratic programming technique is used to study the influence of boundary slip on the lubrication performance of a two-dimensional journal bearing. A numerical model is used to analyze the effect of the cylindrical texture shape on the characteristics of journal bearings. It is concluded that the combination of slip and texture can be an effective approach to improve the performance of hydrodynamic journal bearings. Findings The results show that there is an interfacial shear stress (perfect slip surface) and that the role of the slip regime is to reduce friction. Numerical analyses indicate that the location and size of the slip and texture zone have a large effect on journal bearings. A comparison of the distribution forms of various texture–slip combinations indicates that the full texture–slip combination can prominently reduce the load-carrying capacity and that the “forward-slip backward-texture” configuration can considerably improve the performance of journal bearings. Originality/value The combined effects of boundary slip and texture on hydrodynamic journal bearings are meticulously examined. The patterns of the slip and texture are optimized, which can substantially improve the journal bearing performance.

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Multi‐linearity algorithm for wall slip in two‐dimensional gap flow

Cited by 21 publications

References 31 publications

Identifying the optimal interfacial parameter correlated with hydrodynamic lubrication

Identifying the optimal interfacial parameter correlated with hydrodynamic lubrication

Interplay between wall slip and cavitation: A complementary variable approach

Optimal design of the slip–texture on a journal-bearing surface

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