New Models in the Theory of the Hydrodynamic Lubrication of Rough Surfaces

1988 ◽  
Vol 110 (3) ◽  
pp. 402-407 ◽  
Author(s):  
G. Bayada ◽  
M. Chambat

Recent advances in mathematical analysis of problems described by several small parameters equations are used to revisit the general roughness problem. In this paper, we put forward a new qualitative study of a thin film flow with a rapidly varying gap. Using an asymptotic analysis of the three-dimensional Stokes system we obtain a family of new generalized Reynolds equations. We are led to distinguish three different cases in which the periodic roughness wavelength is on the order of, greater or shorter than the mean thickness of the gap.

Coatings ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 248 ◽  
Author(s):  
Anwar Saeed ◽  
Zahir Shah ◽  
Saeed Islam ◽  
Muhammad Jawad ◽  
Asad Ullah ◽  
...  

In this research, the three-dimensional nanofluid thin-film flow of Casson fluid over an inclined steady rotating plane is examined. A thermal radiated nanofluid thin film flow is considered with suction/injection effects. With the help of similarity variables, the partial differential equations (PDEs) are converted into a system of ordinary differential equations (ODEs). The obtained ODEs are solved by the homotopy analysis method (HAM) with the association of MATHEMATICA software. The boundary-layer over an inclined steady rotating plane is plotted and explored in detail for the velocity, temperature, and concentration profiles. Also, the surface rate of heat transfer and shear stress are described in detail. The impact of numerous embedded parameters, such as the Schmidt number, Brownian motion parameter, thermophoretic parameter, and Casson parameter (Sc, Nb, Nt, γ), etc., were examined on the velocity, temperature, and concentration profiles, respectively. The essential terms of the Nusselt number and Sherwood number were also examined numerically and physically for the temperature and concentration profiles. It was observed that the radiation source improves the energy transport to enhance the flow motion. The smaller values of the Prandtl number, Pr, augmented the thermal boundary-layer and decreased the flow field. The increasing values of the rotation parameter decreased the thermal boundary layer thickness. These outputs are examined physically and numerically and are also discussed.


2009 ◽  
Vol 21 (3) ◽  
pp. 032102 ◽  
Author(s):  
S. J. Baxter ◽  
H. Power ◽  
K. A. Cliffe ◽  
S. Hibberd

2011 ◽  
Vol 50 (5-6) ◽  
pp. 537-542 ◽  
Author(s):  
S. Veremieiev ◽  
H.M. Thompson ◽  
Y.C. Lee ◽  
P.H. Gaskell

1997 ◽  
Vol 119 (1) ◽  
pp. 211-216 ◽  
Author(s):  
Jin Hu ◽  
Hans J. Leutheusser

Micro-inertia effects of surface roughness on hydrodynamic lubrication are analyzed in the light of similitude principles, viz. a newly conceived reduced Reynolds number and the classical parameter of relative roughness. In particular, the dynamic properties of laminar sheet flow in a two-dimensional channel between a sinusoidal wall and a flat wall are studied. FEM solutions of the Navier-Stokes equation are compared with corresponding experimental findings. The latter are gathered in an especially designed laminar-flow wind tunnel. Conclusions are drawn concerning the roughness sensitivity of laminar thin-film flows.


Open Physics ◽  
2016 ◽  
Vol 14 (1) ◽  
pp. 44-64 ◽  
Author(s):  
Remus-Daniel Ene ◽  
Vasile Marinca ◽  
Valentin Bogdan Marinca

AbstractIn this paper the thin film flow of an Oldroyd 6-constant fluid on a vertically moving belt is investigated. The basic equation of a non-Newtonian fluid in a container with a wide moving belt which passes through the container moving vertically upward with constant velocity, is reduced to an ordinary nonlinear differential equation. This equation is solved approximately by means of the Optimal Homotopy Asymptotic Method (OHAM). The solutions take into account the behavior of Newtonian and non-Newtonian fluids. Our procedure intended for solving nonlinear problems does not need small parameters in the equation and provides a convenient way to control the convergence of the approximate solutions.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Saima Riasat ◽  
Muhammad Ramzan ◽  
Seifedine Kadry ◽  
Yu-Ming Chu

Abstract The remarkable aspects of carbon nanotubes like featherweight, durability, exceptional electrical and thermal conduction capabilities, and physicochemical stability make them desirous materials for electrochemical devices. Having such astonishing characteristics of nanotubes in mind our aspiration is to examine the squeezing three dimensional Darcy–Forchheimer hydromagnetic nanofluid thin-film flow amid two rotating disks with suspended multiwalled carbon nanotubes (MWCNTs) submerged into the base fluid water. The analysis is done by invoking partial slip effect at the boundary in attendance of autocatalytic reactions. The mathematical model consists of axial and azimuthal momentum and magnetic fields respectively. The tangential and axial velocity profiles and components of the magnetic field are examined numerically by employing the bvp4c method for varying magnetic, rotational, and squeezing Reynolds number. The torque effect near the upper and lower disks are studied critically using their graphical depiction. The values of the torque at the upper and lower disks are obtained for rotational and squeezed Reynolds numbers and are found in an excellent concurrence when compared with the existing literature. Numerically it is computed that the torque at the lower disk is higher in comparison to the upper disk for mounting estimates of the squeezed Reynolds number and the dimensionless parameter for magnetic force in an axial direction. From the graphical illustrations, it is learned that thermal profile declines for increasing values of the squeezed Reynolds number.


Author(s):  
Sergii Veremieiev ◽  
Philip H. Gaskell ◽  
Yeaw Chu Lee ◽  
Harvey M. Thompson

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