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Showing papers on "Lubrication theory published in 1978"



Journal ArticleDOI
TL;DR: In this article, the authors investigated the effect of circulation induced in the drop and in the lower bulk fluid, and the constriction in the film thickness at its periphery, which tends to slow it down.
Abstract: A small drop of liquid 1 falls through a less dense liquid 2 and approaches the horizontal interface between liquid 2 and an underlying layer of liquid 1. After a short time the drop will be brought to rest (or nearly) in a hollow in the interface. Before the drop can coalesce with its bulk phase, the thin film of liquid 2 trapped between them must be squeezed out, and become sufficiently thin that rupture can occur. This is the film drainage problem. Early calculations, based on simple lubrication theory, fail to take proper account of two effects which are investigated here and shown to be decisive. They are the circulation induced in the drop and in the lower bulk fluid, which tends to speed up drainage, and the constriction in the film thickness at its periphery, which tends to slow it down. This constriction has been observed and some existing theories have attempted to model it in an ad hoc manner. We give here a physical explanation and calculate the minimum thickness explicitly. The effect of circulation in the adjacent fluids is also calculated.

142 citations


01 Oct 1978
TL;DR: In this paper, the authors provided the film-parameter equations for four fluid-film lubrication regimes found in elliptical contacts, i.e., isoviscous-rigid, viscous viscous, elastohydrodynamic, or viscous-elastic.
Abstract: The film-parameter equations are provided for four fluid-film lubrication regimes found in elliptical contacts. These regimes are isoviscous-rigid; viscous-rigid; elastohydrodynamic of low-elastic-modulus materials, or isoviscous-elastic; and elastohydrodynamic, or viscous-elastic. The influence or lack of influence of elastic and viscous effects is the factor that distinguishes these regimes. The film-parameter equations for the respective regimes come from earlier theoretical studies by the authors on elastohydrodynamic and hydrodynamic lubrication of elliptical conjunctions. These equations are restated and the results are presented as a map of the lubrication regimes, with film-thickness contours on a log-log grid of the viscosity and elasticity parameters for five values of the ellipticity parameter. The results present a complete theoretical film-parameter solution for elliptical contacts in the four lubrication regimes.

84 citations


Journal ArticleDOI
TL;DR: In this article, the steady flow of a suspension of closely fitting, neutrally buoyant, incompressible and elastic spheres through a circular cylindrical tube is investigated under the assumption that lubrication theory is valid in the fluid region.
Abstract: The steady flow of a suspension of closely fitting, neutrally buoyant, incompressible and elastic spheres through a circular cylindrical tube is investigated under the assumption that lubrication theory is valid in the fluid region. A series solution giving the displacement field of an elastic incompressible sphere under axisymmetrically distributed surface tractions is developed. It is found that, for closely fitting particles, flow properties of the suspension are strongly dependent on the shear modulus of the elastic material and the velocity of the particle.

65 citations


Journal ArticleDOI
TL;DR: In this paper, a dynamical theory of flow in the asthenosphere is developed by treating it as a thin layer of Newtonian viscous fluid, pushed horizontally by the dense sinking slabs attached to some plates and by the differences in heating under continental and oceanic crust.
Abstract: Summary. A dynamical theory of flow in the asthenosphere is developed by treating it as a thin layer of Newtonian viscous fluid, pushed horizontally by the dense sinking slabs attached to some plates and by the differences in heating under continental and oceanic crust. Two-dimensional lubrication theory is adapted to give the world-wide effects of inflow to the asthenosphere at the slabs, outflow to the plates at mid-ocean ridges, and the horizontal forces applied at the slabs. The resulting torque balance for the plates is better than any previously published, and leads one to conclude that the asthenosphere's viscosity is least at the top.

38 citations


Journal ArticleDOI
01 Jul 1978-Wear
TL;DR: In this paper, a generalized form of the Reynolds equation applicable to mixed lubrication conditions is derived and it is shown that the load capacity increases as surface roughness increases, and a new theory of lubrication for rough surfaces is presented.

25 citations




Journal ArticleDOI
TL;DR: In this paper, the wall shear stresses in pressure flows and shear flows are evaluated based on the friction law of fluid, and their stresses are applied to turbulent lubrication by introducing a concept of equivalent pressure flow.
Abstract: This paper presents one of the methods for deriving a turbulent lubrication equation and a solution for the equation. The turbulent lubrication equation in the study is developed by such a procedure that the wall shear stresses in pressure flows and shear flows are evaluated based on the friction law of fluid, and their stresses are applied to turbulent lubrication by introducing a concept of equivalent pressure flow. From the analytical solutions, the effects of pressure flows on turbulent lubrication which have been neglected hitherto are considered. The effects are remarkable in the superlaminar flow regime in transit from laminar to full turbulent flows.

8 citations


Journal ArticleDOI
01 Nov 1978-Wear
TL;DR: In this paper, the authors derived a new lubrication equation including slip velocity for finite self-acting hydrodynamic porous metal bearings operating in the turbulent regime (fully developed) with a single phase Newtonian incompressible lubricant.

6 citations



Journal ArticleDOI
TL;DR: In this article, an application of the turbulent lubrication theory developed in the first paper to the finite width journal bearings is presented, where the effects of pressure flows on the performances not previously encountered are considered from the analytical results, and compared comparing with the published papers.
Abstract: In this paper, an application of the turbulent lubrication theory developed in the first paper to the finite width journal bearings is presented. Bearing performances such as film pressure, load capacity, frictional force and rate of flow in turbulent flows are evaluated by the numerical analysis. The effects of pressure flows on the performances not previously encountered are considered from the analytical results, and are discussed comparing with the published papers. Also, an experiment in a range of high eccentricities and of the mean Reynolds numbers up to 5000 is conducted to compare with the theoretical results. From agreement of the experimental results with the analytical ones, the validity of the theory is confirmed.

01 Jan 1978
TL;DR: In this article, the authors reviewed basic lubrication theory, and the concepts of convergent wedge, divergent wedge and squeeze film lubrication are treated, and described studies which have been made into the behaviour of lubricated piston rings for large marine engines.
Abstract: Basic lubrication theory is reviewed, and the concepts of convergent wedge, divergent wedge and squeeze film lubrication are treated. The paper then describes studies which have been made into the behaviour of lubricated piston rings for large marine engines. Order from NSFI as No. 14,917.