Results 221 to 230 of about 618 (258)

Drag reduction in a lubricated turbulent channel

2021
Direct numerical simulation (DNS) was utilized to study the drag reduction in a lubricated channel, characterized by the injection of a lubricating fluid layer in the near wall region of a planar channel to favor the transportation of the core fluid. In the present work the fluids have equal density but different viscosity, allowing for the definition ...
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Turbulent Lubrication Flow in an Annular Channel

Journal of Fluids Engineering, 1986
An analytical and experimental study is presented of the lubrication flow in an annular channel with a moving core. Velocity profiles and wall friction were determined over a Reynolds number range up to 3 × 104 and radius ratios of 0.6 and 0.85. The experimental results are shown to be in good agreement with the predictions of a three-layer gradient ...
H. G. Polderman, G. Velraeds, W. Knol
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Designing for turbulent lubrication

International Journal of Mechanical Sciences, 1973
Abstract There are three turbulent lubrication theories which lend themselves to convenient numerical solution of the governing Reynolds' equation. Two of the theories have been subjected to critical analysis in the literature, whilst the third due to Hirs is more recent. The theory of Hirs is considered from the standpoint of the designer.
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On Gas Lubrication in Turbulent Regime

Journal of Basic Engineering, 1964
This paper analyzes first the transient conditions from laminar to turbulent regime for gas lubricated bearings. Then the pressure equation is deduced for self-acting gas-lubricated bearing by using Prandtl’s mixing length theory. A simple method for determining the pressure and the operating characteristics for bearings operating at high numbers H is ...
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An Expression of Reynolds Stresses in Turbulent Lubrication Theory

Journal of Tribology, 1992
This paper proposes an alternative model of Reynolds stresses for turbulent lubrication theory. The approach relies on Prandtl’s mixing length theory which is based on a modified Van Driest mixing formula [1]. However, unlike the previous theories [2, 3] the proposed equation is capable of accounting for the effect of shear stress gradient on the ...
A. K. Tieu, P. B. Kosasih
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Transient Lubricating Films With Inertia—Turbulent Flow

Journal of Tribology, 1984
This paper presents some new equations for the treatment of turbulent lubricating films when the effects of inertia cannot be neglected. The eddy-viscosity concept is used to represent the turbulent stresses in terms of mean-velocity gradient. Transient and steady-state operation are both considered by means of a generalized stream-function-pressure ...
H. G. Elrod, I. Anwar, R. Colsher
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Turbulent drag reduction by compliant lubricating layer

Journal of Fluid Mechanics, 2019
We propose a physically sound explanation for the drag reduction mechanism in a lubricated channel, a flow configuration in which an interface separates a thin layer of less-viscous fluid (viscosity $\unicode[STIX]{x1D702}_{1}$) from a main layer of a more-viscous fluid (viscosity $\unicode[STIX]{x1D702}_{2}$).
Alessio Roccon, Francesco Zonta, Alfredo Soldati   +2 more
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A Bulk-Flow Theory for Turbulence in Lubricant Films

Journal of Lubrication Technology, 1973
The purpose of this study on the turbulent lubricant film is: 1 To give a brief outline of a new theory called bulk-flow theory; 2 To investigate to what extent results of theories based on law of wall and mixing length concept agree with the newly developed theory; 3 To provide a theoretical basis for the design of bearings lubricated by fluids of low
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Hydrodynamic Lubrication of Face Seal in a Turbulent Flow Regime

Journal of Tribology, 1996
Abstract Models for thermohydrodynamic lubrication in the turbulent regime are developed for a mechanical end face seal with various combinations of asperity height and roughness pattern. A surface wear model, based on deformation, is established for mixed lubrication such that the displacement is at most equal to the mean asperity ...
Jen Fin Lin, Chih Chung Yao
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Application of Energy Model of Turbulence to Calculation of Lubricant Flows

Journal of Lubrication Technology, 1974
A turbulent energy model for determination of turbulent stresses is used to calculate velocity profiles in lubricant films. The results agree very well with the predictions of the previously established turbulent lubrication theory of Elrod, Ng, and Pan.
Mein-Kai Ho, J. H. Vohr
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