Partial Hydrodynamic Lubrication With Large Fractional Contact Areas

1998 ◽  
Vol 120 (1) ◽  
pp. 16-20 ◽  
Author(s):  
W. R. D. Wilson ◽  
N. Marsault
Keyword(s):  
Metal Forming ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Full Range ◽  
Surface Pattern ◽  
Empirical Equations ◽  
Height Distribution ◽  
Contact Conditions ◽  
Initial Height ◽  
Semi Empirical

An alternative average Reynolds equation for use under conditions of large fractional contact area is proposed. The flow factors for this form of the equation are calculated for a variety of longitudinal surfaces and the results are shown to be relatively insensitive to the initial height distribution. Pressure and shear flow factors for the Christensen height distribution and a variety of Peklenik surface pattern parameters are also derived from the work of Patir and Cheng, Lo and Tripp. These are represented by semi-empirical equations over the full range of contact conditions. The implications of the results, with respect to the lubrication of metal forming processes, is discussed.

scholarly journals Reaeration and oxygen dissipation into a circular hydraulic channel: experimental and dimensionless approach

RBRH ◽  
2018 ◽  
Vol 23 (0) ◽  
Author(s):  
Felipe Keiji Feital Harano ◽  
Murilo de Souza Ferreira ◽  
Marcos Vinícius Mateus ◽  
Deusmaque Carneiro Ferreira ◽  
Julio Cesar de Souza Inácio Gonçalves
Keyword(s):  
Interfacial Phenomena ◽  
Linear Regression Method ◽  
Hydraulic Parameters ◽  
Empirical Equations ◽  
Hydraulic Conditions ◽  
Do Concentration ◽  
Hydraulic Channel ◽  
M Estimates ◽  
Semi Empirical ◽  
Key Parameter

ABSTRACT Dissolved oxygen (DO) is a key parameter in water quality. The DO concentration in a water body can be changed by interfacial phenomena such as reaeration and oxygen dissipation, which can be represented by the coefficients K2 and KD, respectively. Few studies have jointly correlated K2 and KD with physical and hydraulic parameters of the channel. The present work investigated the behavior of these coefficients over a range of hydraulic conditions, and developed semi-empirical equations capable of relating both coefficients. Reaeration and DO dissipation tests were conducted in a circular hydraulic channel with flow velocity ranging from 0.20 to 0.79 m.s-1 and depth ranging from 0.09 to 0.15 m. Estimates of K2 and KD were performed using the non-linear regression method. Semi-empirical equations were obtained based on classical dimensional analysis and multiple regression analysis. The comparison between measured and estimated coefficients yielded R2 for reaeration and dissipation of 0.940 and 0.844, respectively. KD was higher than K2 for all turbulence levels applied at the hydraulic channel. An estimate obtained by the relation between the semi-empirical equations indicates that the transfer of oxygen in the water-air direction (dissipation) is approximately twice as fast as the transfer in the air-water direction (reaeration).

On the effects of two-dimensional Reynolds roughness in hydrodynamic lubrication

1978 ◽  
Vol 364 (1716) ◽  
pp. 89-106 ◽  
Keyword(s):  
Surface Roughness ◽  
Numerical Computation ◽  
Autocorrelation Function ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
The Other ◽  
Roughness Height ◽  
Two Dimensional ◽  
Roughness Effects ◽  
Dimensional Surface

The hydrodynamic lubrication of rough surfaces is analysed with the Reynolds equation, whose application requires the roughness spacing to be large, and the roughness height to be small, compared with the thick­ness of the fluid film. The general two-dimensional surface roughness is considered, and results applicable to any roughness structure are obtained. It is revealed analytically that two types of term contribute to roughness effects: one depends on the shape of the autocorrelation function and the other does not. The former contribution was neglected by previous workers. The numerical computation of an example shows that these two contributions are comparable in magnitude.

Development of a Mathematical Model for Performance Prediction of Planing Catamaran in Calm Water

2019 ◽  
Vol 161 (A2) ◽  
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Performance Prediction ◽  
Data Evaluation ◽  
Empirical Equations ◽  
Calm Water ◽  
Semi Empirical ◽  
The Mathematical Model ◽  
Comparison With Experimental Data

In this paper, an attempt has been made to predict the performance of a planing catamaran using a mathematical model. Catamarans subjected to a common hydrodynamic lift, have an extra lift between the two asymmetric half bodies. In order to develop a mathematical model for performance prediction of planing catamarans, existing formulas for hydrodynamic lift calculation must be modified. Existing empirical and semi-empirical equations in the literature have been implemented and compared against available experimental data. Evaluation of lift in comparison with experimental data has been documented. Parameters influencing the interaction between demi-hulls and separation effects have been analyzed. The mathematical model for planing catamarans has been developed based on Savitsky’s method and results have been compared against experimental data. Finally, the effects of variation in hull geometry such as deadrise angle and distance between two half bodies on equilibrium trim angle, resistance and wetted surface have been examined.

scholarly journals An Analytical Method for the Determination of Temperature Distribution in Short Journal Bearing Oil Film

Symmetry ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 539
Author(s):  
Nebojsa Nikolic ◽  
Zivota Antonic ◽  
Jovan Doric ◽  
Dragan Ruzic ◽  
Stjepan Galambos ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Oil Film ◽  
Symmetric Geometry ◽  
Experimental Values ◽  
Operating Regimes ◽  
Level Of Agreement

The aim of this paper is to derive an equation for the temperature distribution in journal bearing oil film, in order to predict the thermal load of a bearing. This is very important for the prevention of critical regimes in a bearing operation. To achieve the goal, a partial differential equation of the temperature field was first derived, starting from the energy equation coupled with the Reynolds equation of hydrodynamic lubrication for a short bearing of symmetric geometry. Then, by solving the equation analytically, the function of temperature distribution in the bearing oil film has been obtained. The solution is applied to the journal bearing, for which the experimental data are available in the references. Finally, the obtained results have been compared to the corresponding experimental values for two operating regimes, and a good level of agreement was achieved.

ALE finite elements with hydrodynamic lubrication for metal forming

1992 ◽  
Vol 138 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Wing Kam Liu ◽  
Yu-Kan Hu ◽  
Ted Belytschko
Keyword(s):  
Finite Elements ◽  
Metal Forming ◽  
Hydrodynamic Lubrication

Studies on Micro Plasto Hydrodynamic Lubrication in Metal Forming

2002 ◽  
pp. 115-134 ◽  
Author(s):  
Niels Bay ◽  
Jakob I. Bech ◽  
Jan L. Andreasen ◽  
Ichiro Shimizu
Keyword(s):  
Metal Forming ◽  
Hydrodynamic Lubrication

scholarly journals SPH modelling of hydrodynamic lubrication: laminar fluid flow–structure interaction with no-slip conditions for slider bearings

2020 ◽  
Author(s):  
Marco Paggi ◽  
Andrea Amicarelli ◽  
Pietro Lenarda
Keyword(s):  
Reynolds Equation ◽  
Stokes Equations ◽  
Hydrodynamic Lubrication ◽  
Flow Direction ◽  
Navier Stokes ◽  
Slider Bearing ◽  
Fluid Films ◽  
Slip Conditions ◽  
Application Fields ◽  
New Research

Abstract The FOSS CFD-SPH code SPHERA v.9.0.0 (RSE SpA) is improved to deal with “fluid–solid body” interactions under no-slip conditions and laminar regimes for the simulation of hydrodynamic lubrication. The code is herein validated in relation to a uniform slider bearing (i.e. for a constant lubricant film depth) and a linear slider bearing (i.e. for a film depth with a linear profile variation along the main flow direction). Validations refer to comparisons with analytical solutions, herein generalized to consider any Dirichlet boundary condition. Further, this study allows a first code validation of the “fluid–fixed frontier” interactions under no-slip conditions. With respect to the most state-of-the-art models (2D codes based on Reynolds’ equation for fluid films), the following distinctive features are highlighted: (1) 3D formulation on all the terms of the Navier–Stokes equations for incompressible fluids with uniform viscosity; (2) validations on both local and global quantities (pressure and velocity profiles; load-bearing capacity); (3) possibility to simulate any 3D topology. This study also shows the advantages of using a CFD-SPH code in simulating the inertia and 3D effects close to the slider edges, and it opens new research directions overcoming the limitations of the codes for hydrodynamic lubrication based on the Reynolds’ equation for fluid films. This study finally allows SPHERA to deal with hydrodynamic lubrication and improves the code for other relevant application fields involving fluid–structure interactions (e.g. transport of solid bodies by floods and earth landslides; rock landslides). SPHERA is developed and distributed on a GitHub public repository.

scholarly journals Nonlinear Reynolds equation for hydrodynamic lubrication

2015 ◽  
Vol 39 (17) ◽  
pp. 5299-5309 ◽  
Author(s):  
Tom Gustafsson ◽  
K.R. Rajagopal ◽  
Rolf Stenberg ◽  
Juha Videman
Keyword(s):  
Reynolds Equation ◽  
Hydrodynamic Lubrication

Mathematical Modeling of Drying Kinetics of Salted Otolithes Ruber at the Different Temperature

2013 ◽  
Vol 781-784 ◽  
pp. 1347-1352 ◽  
Author(s):  
Yan Yan Wu ◽  
Zhong Yang Ren ◽  
Lai Hao Li ◽  
Xian Qing Yang ◽  
Wan Ling Lin ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Experimental Data ◽  
Suitable Model ◽  
Empirical Equations ◽  
Thin Layer Drying ◽  
Electric Oven ◽  
Otolithes Ruber ◽  
Predicted Values ◽  
Semi Empirical ◽  
Kinetics Of

Salted Otolithes ruber with 80 (±5) g weight on dry basis were dried in the blast electric oven using different temperature (20, 30, 40 and 50°C) until the humidity fell down to 0.6 from 1.23 on dry basis. Drying processes were completed between 20-48h. In this study, experiment values were compared with predicted values obtained from twenty thin layer drying theoretical/ semi-empirical/ empirical equations. Models whose coefficient of correlation (R2) values are highest were chosen to be the best models. According to this, Midillis Model was defined as the most suitable model in which predicted value is closest to experimental data for 20°C level, Weibulls model was for 30°C level, Weibull distributions model was for 40°C level and Alibas model was for 50°C level.

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