High-pressure rheology of lubricants and limitations of the Reynolds equation

Bair, Scott; Khonsari, M. M.; Winer, W. O.

doi:10.1016/s0301-679x(98)00078-4

Cited by 93 publications

(60 citation statements)

References 20 publications

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“…(B5). Bair et al [24] noticed this divergence and established a criterion for the validity of the lubrication equations withdependent viscosity in terms of a condition on the maximum principal stress in the fluid. Setting …”

Section: Appendix B: Lubrication Scalingmentioning

confidence: 99%

“…3D studies of such "piezoviscous" liquids have used exponential and power-law η(p) relations, particularly in the contexts of polymer melt processing [20,21] and lubricating oils under exceedingly high pressures [22,23]. Such flows may depart from the classical Newtonian solutions [22,24], e.g., the extrusion flux of polymer melts may slow dramatically under high pressures [21].…”

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confidence: 99%

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Pressure-dependent surface viscosity and its surprising consequences in interfacial lubrication flows

Manikantan

Squires

2017

Phys. Rev. Fluids

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Section: Appendix B: Lubrication Scalingmentioning

confidence: 99%

mentioning

confidence: 99%

Pressure-dependent surface viscosity and its surprising consequences in interfacial lubrication flows

Manikantan

Squires

2017

Phys. Rev. Fluids

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“…The lubricant had  o = 0.039 Pas, while its pressure-viscosity response was described by a third order polynomial as Equ. 42, determined by best-fitting viscosity data in [94].…”

Section: Eyring Versus Carreau-yasudamentioning

confidence: 99%

“…Bair and Winer refer to this as the response time and indicate that it is as low as 3 ms for their isothermal viscometer [60]. If this value, the thermal properties of Bair's viscometer [94] and a gap size of h = 2 m are inserted into Equ. 45 we obtain;…”

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confidence: 99%

History, Origins and Prediction of Elastohydrodynamic Friction

2014

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There is currently considerable debate concerning the most appropriate rheological model to describe the behaviour of lubricant films in rolling-sliding, elastohydrodynamic contacts. This is an important issue since an accurate model is required in to predict friction in such contacts. This paper reviews the origins of this debate, which primarily concerns a divergence of views between researchers using high pressure, high shear rate viscometry and those concerned with the measurement and analysis of elastohydrodynamic friction; the former advocate a Carreau-based shear stress/strain rate model while the latter generally favour an Eyring-based one. The crucial importance of accounting for shear heating effects in analysing both viscometric and friction data is discussed. The main criticisms levied by advocates of a Carreau-based model against Eyring's model are discussed in some detail. Finally the ability of both types of rheological model to fit elastohydrodynamic friction measurements for a quite simple, well-defined base fluid is tested, using previously-measured pressure-viscosity behaviour for the fluid. Both models appear to fit the experimental data over a wide temperature range quite well, though fit of the Eyring model appears slightly closer than that of the Carreau-Yasuda model. Friction data from a wider range of welldefined fluid types is needed to identify categorically the most appropriate model to describe elastohydrodynamic friction.

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“…Bridgman [6] in his book cites a personal communication from Andrade that provides a relationship of the viscosity to the temperature, density and pressure 1 (see also the discussion in [10]). There has been a great deal of experimental data since Bridgman's book that document the variation of viscosity with pressure (see [11,12,13,14,15,16,17,18,19,20,21,22]). In most liquids, while the variation in the viscosity can be of the order of 10 8 (see Bair and Kottke [21]), the variation of the density due to variation in the pressure is of the order of a few percent (see Dowson and Higginson [23], Rajagopal [24]), and thus it would be reasonable to assume that the liquid is incompressible while the visocity varies with the pressure.…”

Section: R a F T (5)mentioning

confidence: 99%

Flow of a Fluid Through a Porous Solid Due to High Pressure Gradients

2013

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Abstract. It is well known that the viscosity of fluids could vary by several orders of magnitude with pressure. This fact is not usually taken into account in many important applications involving the flow of fluids through a porous media, like the problems of enhanced oil recovery or carbon dioxide sequestration where very high pressure differentials are involved. Another important technical problem where such high pressure differentials are involved is that of extracting unconventional oil deposits such as shale which is becoming ever so important now. In this study, we show that the traditional approach that ignores the variation of the viscosity and drag with the pressure greatly over-predicts the mass flux taking place through the porous structure. While taking the pressure dependence of viscosity and drag leads to a ceiling flux, the traditional approaches lead to a continued increase in the flux with the pressure difference. In this study, we consider a generalization of the classical Brinkman equation that takes the dependence of the viscosity and the Drag coefficient on pressure. To our knowledge, this is the first study to carry out such an analysis.

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High-pressure rheology of lubricants and limitations of the Reynolds equation

Cited by 93 publications

References 20 publications

Pressure-dependent surface viscosity and its surprising consequences in interfacial lubrication flows

Pressure-dependent surface viscosity and its surprising consequences in interfacial lubrication flows

History, Origins and Prediction of Elastohydrodynamic Friction

Flow of a Fluid Through a Porous Solid Due to High Pressure Gradients

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