Micro-Inertia Effects in Laminar Thin-Film Flow Past a Sinusoidal Boundary

1997 ◽  
Vol 119 (1) ◽  
pp. 211-216 ◽  
Author(s):  
Jin Hu ◽  
Hans J. Leutheusser
Keyword(s):  
Thin Film ◽  
Film Flow ◽  
Hydrodynamic Lubrication ◽  
Dynamic Properties ◽  
Navier Stokes ◽  
Thin Film Flow ◽  
Navier Stokes Equation ◽  
Inertia Effects ◽  
Experimental Findings ◽  
Film Flows

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.

Inertia Effects in Thin Film Flow With a Corrugated Boundary

1991 ◽  
Vol 58 (1) ◽  
pp. 272-277 ◽  
Author(s):  
Ilter Serbetci ◽  
John A. Tichy
Keyword(s):  
Pressure Distribution ◽  
Film Flow ◽  
Stokes Equations ◽  
Lubrication Theory ◽  
Navier Stokes ◽  
Thin Film Flow ◽  
Perturbation Expansions ◽  
Navier Stokes Equations ◽  
Inertia Effects ◽  
Grooved Surface

An analytical solution is presented for two-dimensional, incompressible film flow between a sinusoidally grooved (or rough) surface and a flat surface. The upper grooved surface is stationary whereas the lower, smooth surface moves with a constant speed, The Navier-Stokes equations were solved employing both mapping techniques and perturbation expansions. Due to the inclusion of the inertia effects, a different pressure distribution is obtained than predicted by the classical lubrication theory. In particular, the amplitude of the pressure distribution of the classical lubrication theory is found to be in error by over 100 percent (for modified Reynolds number of 3–4).

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
Keyword(s):  
Thin Film ◽  
Qualitative Study ◽  
Stokes System ◽  
Film Flow ◽  
Hydrodynamic Lubrication ◽  
Three Dimensional ◽  
Thin Film Flow ◽  
New Models ◽  
Small Parameters ◽  
The Mean

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.

scholarly journals Optimal Homotopy Asymptotic Method for a thin film flow of a pseudo plastic fluid draining down or lifting up on a cylindrical surface

2013 ◽  
Vol 19 (4) ◽  
pp. 513-527
Author(s):  
Kamran Alam ◽  
M.T. Rahim ◽  
S. Islam ◽  
A.M. Sidiqqui
Keyword(s):  
Thin Film ◽  
Asymptotic Method ◽  
Cylindrical Surface ◽  
Film Flow ◽  
Vertical Cylinder ◽  
Stokes Number ◽  
Velocity Shear ◽  
Thin Film Flow ◽  
Fluid Velocities ◽  
Optimal Homotopy Asymptotic Method

In this study, the pseudo plastic model is used to obtain the solution for the steady thin film flow on the outer surface of long vertical cylinder for lifting and drainage problems. The non-linear governing equations subject to appropriate boundary conditions are solved analytically for velocity profiles by a modified homotopy perturbation method called the Optimal Homotopy Asymptotic method. Expressions for the velocity profile, volume flux, average velocity, shear stress on the cylinder, normal stress differences, force to hold the vertical cylindrical surface in position, have been derived for both the problems. For the non-Newtonian parameter ?=0, we retrieve Newtonian cases for both the problems. We also plotted and discussed the affect of the Stokes number St, the non-Newtonian parameter ? and the thickness ? of the fluid film on the fluid velocities.

scholarly journals MHD thin film flow of the Oldroyd-B fluid together with bioconvection and activation energy

2021 ◽  
pp. 101218
Author(s):  
Farhan Ahmad ◽  
Taza Gul ◽  
Imran Khan ◽  
Anwar Saeed ◽  
Mahmoud Mohamed Selim ◽  
...  
Keyword(s):  
Thin Film ◽  
Activation Energy ◽  
Film Flow ◽  
Thin Film Flow

Numerical and experimental study on the dynamic bearing properties of a four-pad and eight-pad tilting pad journal bearings in a vertical rotor

2021 ◽  
pp. 1-24
Author(s):  
Gudeta Berhanu Benti ◽  
David Jose Rondon ◽  
Rolf Gustavsson ◽  
Jan-Olov Aidanpää
Keyword(s):  
Dynamic Properties ◽  
Mean Value ◽  
Journal Bearings ◽  
Navier Stokes ◽  
Rigid Rotor ◽  
Navier Stokes Equation ◽  
Vertical Rotor ◽  
Tilting Pad ◽  
Fifth Order ◽  
Tilting Pad Journal Bearings

Abstract In this paper, the dynamics of tilting pad journal bearings with four and eight pads are studied and compared experimentally and numerically. The experiments are performed on a rigid vertical rotor supported by two identical bearings. Two sets of experiments are carried out under similar test setup. One set is performed on a rigid rotor with two four-pad bearings, while the other is on a rigid rotor with two eight-pad bearings. The dynamic properties of the two bearing types are compared with each other by studying the unbalance response of the system at different rotor speeds. Numerically, the test rig is modeled as a rigid rotor and the bearing coefficients are calculated based on Navier-Stokes equation. A nonlinear bearing model is developed and used in the steady state response simulation. The measured and simulated displacement and force orbits show similar patterns for both bearing types. Compared to the measurement, the simulated mean value and range (peak-to-peak amplitude) of the bearing force deviate with a maximum of 16 % and 38 %, respectively. It is concluded that, unlike the eight-pad TPJB, the four-pad TPJB excite the system at the third and fifth-order frequencies, which are due to the number of pads, and the amplitudes of these frequencies increase with the rotor speed.

Axisymmetric thin film flow on a flat disk foil subject to intense radial electric fields

2022 ◽  
Vol 34 (1) ◽  
pp. 012109
Author(s):  
Z. Wang ◽  
C. Zhang ◽  
H. Xia ◽  
Q. Xie ◽  
W. Deng
Keyword(s):  
Thin Film ◽  
Electric Fields ◽  
Film Flow ◽  
Thin Film Flow ◽  
Flat Disk
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