Turbulence Lubrication Models

2013 ◽  
pp. 3927-3932
Author(s):  
John Tichy
Keyword(s):  
Lubrication Models

Hydrodynamic Pressure of Thrust Step Bearings

2009 ◽  
Author(s):  
Shuangbiao Liu ◽  
W. Wayne Chen ◽  
Diann Y. Hua
Keyword(s):  
Analytical Solution ◽  
Coordinate System ◽  
Laplace Equation ◽  
Analytical Solutions ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Hydrodynamic Pressure ◽  
Finite Width ◽  
Cylindrical Coordinate ◽  
Lubrication Models

Step bearings are frequently used in industry for better load capacity. Analytical solutions to the Rayleigh step bearing and a rectangular slider with a finite width are available in literature, but none for a fan-shaped thrust step bearing. This study starts with a known solution to the Laplace equation in a cylindrical coordinate system, which is in the form of infinite summation. An analytical solution to pressure is derived in this paper for hydrodynamic lubrication problems encountered in the fan-shaped step bearing. The presented solutions can be useful for designers to maximize bearing performance as well as for researchers to benchmark numerical lubrication models.

A Comparison of Flow Fields Predicted by Various Turbulent Lubrication Models With Existing Measurements

1999 ◽  
Vol 122 (2) ◽  
pp. 475-477 ◽  
Author(s):  
Xiaojing Wang ◽  
Zhiming Zhang ◽  
Meili Sun
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Couette Flow ◽  
Flow Fields ◽  
Countercurrent Flow ◽  
Lubrication Models

Flow field predictions of various turbulent lubrication models are compared with the existing experimental data of turbulent Couette flow and shear-induced countercurrent flow. [S0742-4787(00)00502-6]

scholarly journals On the multiple solutions of coating and rimming flows on rotating cylinders

2017 ◽  
Vol 835 ◽  
pp. 540-574 ◽  
Author(s):  
André v. B. Lopes ◽  
Uwe Thiele ◽  
Andrew L. Hazel
Keyword(s):  
Stokes Equations ◽  
Bond Number ◽  
Lubrication Approximation ◽  
Dynamics Model ◽  
Rotation Rates ◽  
Gravitational Forces ◽  
Number Ratio ◽  
Gradient Dynamics ◽  
Steady Solutions ◽  
Lubrication Models

We consider steady solutions of the Stokes equations for the flow of a film of fluid on the outer or inner surface of a cylinder that rotates with its axis perpendicular to the direction of gravity. We find that previously unobserved stable and unstable steady solutions coexist over an intermediate range of rotation rates for sufficiently high values of the Bond number (ratio of gravitational forces relative to surface tension). Furthermore, we compare the results of the Stokes calculations to the classic lubrication models of Pukhnachev (J. Appl. Mech. Tech. Phys., vol 18, 1977, pp. 344–351) and Reisfeld & Bankoff (J. Fluid Mech., vol. 236, 1992, pp. 167–196); an extended lubrication model of Benilov & O’Brien (Phys. Fluids, vol. 17, 2005, 052106) and Evans et al. (Phys. Fluids, vol. 16, 2004, pp. 2742–2756); and a new lubrication approximation formulated using gradient dynamics. We quantify the range of validity of each model and confirm that the gradient-dynamics model is most accurate over the widest range of parameters, but that the new steady solutions are not captured using any of the simplified models because they contain features that can only be described by the full Stokes equations.

EHL Film Thickness Computations at Low Speeds: Risk of Artificial Trends as a Result of Poor Accuracy and Implications for Mixed Lubrication Modelling

2005 ◽  
Vol 219 (4) ◽  
pp. 285-290 ◽  
Author(s):  
C. H. Venner
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Validity Of Results ◽  
Erroneous Conclusion ◽  
Low Speeds ◽  
Lubrication Models ◽  
Circular Contact

When numerical and experimental results are compared to validate elasto-hydrodynamic lubrication (EHL) models, it is of utmost importance that grid-converged results are used. In particular at low speeds and high loads, solutions obtained using grids that are not sufficiently dense will exhibit an artificial trend that does not represent the behaviour of the continuous modelling equations. As it coincides with a trend observed in experiments this may lead to the erroneous conclusion that the theoretical model on which the numerical simulations are based is accurate. This risk is illustrated in detail. It is further shown that EHL models based on the Reynolds equation in a steady state circular contact predicts a positive film thickness as long as the grid used in the calculations is sufficiently dense. This has significant implications for the validity of results obtained using mixed lubrication models based on a Reynolds model and a film thickness threshold.

scholarly journals Conservation Laws of Some Physical Models via Symbolic Package GeM

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Rehana Naz ◽  
Imran Naeem ◽  
M. Danish Khan
Keyword(s):  
Evolution Equation ◽  
Conservation Laws ◽  
Poisson Equation ◽  
Conservation Law ◽  
Direct Method ◽  
Physical Models ◽  
Lubrication Models

We study the conservation laws of evolution equation, lubrication models, sinh-Poisson equation, Kaup-Kupershmidt equation, and modified Sawada-Kotera equation. The symbolic software GeM (Cheviakov (2007) and (2010)) is used to derive the multipliers and conservation law fluxes. Software GeM is Maple-based package, and it computes conservation laws by direct method and first homotopy and second homotopy formulas.

scholarly journals A lubrication model of coating flows over a curved substrate in space

2002 ◽  
Vol 454 ◽  
pp. 235-261 ◽  
Author(s):  
R. VALÉRY ROY ◽  
A. J. ROBERTS ◽  
M. E. SIMPSON
Keyword(s):  
Three Dimensional ◽  
Multiple Scale ◽  
Fluid Films ◽  
Coating Flows ◽  
Wide Range ◽  
Film Thinning ◽  
Curved Substrate ◽  
Further Development ◽  
Complex Curvature ◽  
Lubrication Models

Consider the three-dimensional flow of a viscous Newtonian fluid upon an arbitrarily curved substrate when the fluid film is thin as occurs in many draining, coating and biological flows. We drive the lubrication model of the dynamics of the film expressed in terms of the film thickness. The comprehensive model accurately includes the effects of the curvature of the substrate, via a physical multiple-scale approach, and gravity and inertia, via more rigorous centre manifold techniques. This new approach theoretically supports the use of the model over a wide range of parameters and provides a sound basis for further development of lubrication models. Numerical simulations exhibit some generic features of the dynamics of such thin fluid films on substrates with complex curvature: we here simulate a film thinning at a corner, the flow around a torus, and draining of a film down a cylinder. The last is more accurate than other lubrication models. The model derived here describes well thin-film dynamics over a wide range of parameter regimes.

scholarly journals A mixed thermal elastohydrodynamic lubrication model of rotary lip seal

2020 ◽  
Vol 103 (1) ◽  
pp. 003685041988190
Author(s):  
Xiaokai Huang ◽  
Shouwen Liu ◽  
Chao Zhang
Keyword(s):  
Simulation Study ◽  
Elastohydrodynamic Lubrication ◽  
Fluid Viscosity ◽  
Asperity Contact ◽  
Influence Of Temperature ◽  
Lip Seal ◽  
Sealing Performance ◽  
Proposed Model ◽  
Influence Of Temperature On ◽  
Lubrication Models

Rotary lip seal is used in various applications where the rotation shaft needs to be sealed, such as hydraulic pumps, fuel pumps, camshafts, crankshafts, and so on. Many thermal elastohydrodynamic lubrication models of rotary lip seal have been introduced, and most of these models neglect the asperity contact. This article proposes a mixed thermal elastohydrodynamic lubrication model of rotary lip seal, in which the microstructure of sealing lip surface, influence of temperature on fluid viscosity, and deformation of lip surface, as well as the asperity contact, are taken into consideration. Simulation study is carried out, and the results show that the asperity contact should not be neglected for analyzing the sealing performance of the rotary lip seal. The influence of speed on the sealing performance is also analyzed based on the proposed model.

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