scholarly journals A Multicoefficient Slip-Corrected Reynolds Equation for Micro-Thin Film Gas Lubrication

2005 ◽  
Vol 2005 (2) ◽  
pp. 105-111 ◽  
Author(s):  
Eddie Yin-Kwee Ng ◽  
Ningyu Liu
Keyword(s):  
Slip Velocity ◽  
Reynolds Equation ◽  
Flow Model ◽  
Slip Flow ◽  
Velocity Model ◽  
Slip Model ◽  
Direct Simulation ◽  
Control Techniques ◽  
Linearized Boltzmann Equation ◽  
Quality Control Techniques

This work investigates and analyzes the performance of conventional slip models among various regimes of Knudsen number and developes a new multicoefficient slip-velocity model, by using Taguchi quality control techniques and numerical analysis. A modified Reynolds equation is also derived based on the new slip-flow model. The multicoefficient slip model and its slip-corrected Reynolds equation are suitable to a wide Knudsen range from slip to transition regime. In comparison with other conventional slip models, it is found that the current results have a better agreement with the solution obtained from the linearized Boltzmann equation and direct simulation of Monte Carlo method (DSMC).

High Knudsen Number Molecular Rarefaction Effects in Gas-Lubricated Slider Bearings for Computer Flying Heads

1987 ◽  
Vol 109 (2) ◽  
pp. 276-282 ◽  
Author(s):  
Y. Mitsuya ◽  
T. Ohkubo
Keyword(s):  
Film Thickness ◽  
Reynolds Equation ◽  
Flow Model ◽  
Slip Flow ◽  
Ambient Air ◽  
Mean Free Path ◽  
Lubricating Film ◽  
Modified Reynolds Equation ◽  
Air Film ◽  
Rarefaction Effects

This paper presents a study into the gas lubrication capability of an ultra-thin 0.025 μm film (converted value for ambient air film). The experimental results obtained using subambient helium as the lubricating film are compared with the calculated results using the modified Reynolds equation considering flow slippage due to the molecular mean free path effects. This comparison confirms that the slip flow model holds true within the range of the present experiments, and that the modified Reynolds equation is applicable for designing the computer flying heads operating at such thin spacing. The reason for the excellent agreement is discussed considering the locality of rarefaction effects on the lubricating surfaces and the anisotropy of these effects between the film thickness and the slider width.

Thin Spacing Analysis for Head-Tape Interface

1996 ◽  
Vol 118 (4) ◽  
pp. 800-806 ◽  
Author(s):  
Kazuo Sakai ◽  
Yasumasa Nagawa ◽  
Koetsu Okuyama ◽  
Takao Terayama
Keyword(s):  
Surface Roughness ◽  
Boltzmann Equation ◽  
Flow Model ◽  
Slip Flow ◽  
First Order ◽  
Lubrication Equation ◽  
Linearized Boltzmann Equation ◽  
Deformation Equation ◽  
High Density Magnetic Recording ◽  
Average Flow Model

Very thin head-tape spacing, combining contact and floating conditions, is investigated for high density magnetic recording. A generalized lubrication equation, based on a linearized Boltzmann equation, is coupled with the tape deformation equation for analysis. Tape-surface roughness is also taken into account in the lubrication equation. The average flow model is adopted to analyzing tape-surface roughness. For very thin spacing conditions, it is found that the spacing based on the linearized Boltzmann equation is smaller than that based on first-order slip flow, and larger than that based on second-order slip flow. It is also found that considering tape-surface roughness reduces the calculated minimum spacing. Analytical results agreed with the experimental ones.

scholarly journals Combined effect of deformation and slip velocity on the performance of a Ferrofluid squeeze film in infinitely long porous rough rectangular plates

10.29007/v873 ◽  
2018 ◽  
Author(s):  
Mukesh Shimpi ◽  
Gunumani M Deheri
Keyword(s):  
Adverse Effect ◽  
Fluid Flow ◽  
Performance Characteristic ◽  
Slip Velocity ◽  
Flow Model ◽  
Type Equation ◽  
Squeeze Film ◽  
Rectangular Plates ◽  
Slip Model ◽  
Slip Coefficient

This investigation aims to study the performance characteristic of a Ferrofluid based squeeze film in infinitely long porous transversely rough rectangular plates considering the effect of deformation and slip velocity. The magnetic fluid flow model of Neuringer and Rosenweig has been used. Beavers – Joseph slip model has been adopted and the stochastic method of Christensen and Tonder has been deployed for roughness. The associated stochastically averaged Reynolds’ type equation is solved. The results prove that the Ferrofluid lubrication offers a limited help in reducing the adverse effect of slip velocity, deformation and porosity, even in the case of negatively skewed roughness. However, the situation improves when variance (- ve) occurs and lower to moderate values of deformation is involved. Aside, this study shows that the slip coefficient has to be at the reduced level an improvement of the bearing performance.

Modified Reynolds Equation for Ultra-Thin Film Gas Lubrication Using 1.5-Order Slip-Flow Model and Considering Surface Accommodation Coefficient

1993 ◽  
Vol 115 (2) ◽  
pp. 289-294 ◽  
Author(s):  
Y. Mitsuya
Keyword(s):  
Thin Film ◽  
Reynolds Equation ◽  
Flow Model ◽  
Slip Flow ◽  
Accommodation Coefficient ◽  
Second Order ◽  
Flow Models ◽  
Gas Lubrication ◽  
Modified Reynolds Equation ◽  
Ultra Thin Film

A 1.5-order modified Reynolds equation for solving the ultra-thin film gas lubrication problem is derived by using an accurate higher-order slip-flow model. This model features two key differences from the current second-order slip-flow model. One is the involvement of an accommodation coefficient for momentum. The other is that the coefficient of the second-order slip-flow term is 4/9 times smaller than that for the current model. From the physical consideration of momentum transfer, the accommodation coefficient is found to have no affect on the second-order slip-flow term. Numerical calculations using the 1.5-order modified Reynolds equation are performed. The results are compared with those obtained using three kinds of currently employed modified Reynolds equations: those employing the first- and second-order slip-flow models and those utilizing the Boltzmann equation. These comparisons confirm that the present modified Reynolds equation provides intermediate characteristics between those derived from the first- and second-order slip-flow models, and produces an approximation closer to the exact solution resulting from the Boltzmann-Reynolds equation.

scholarly journals Effects of Gas Rarefaction on Dynamic Characteristics of Micro Spiral-Grooved Thrust Bearing

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Ren Liu ◽  
Xiao-Li Wang ◽  
Xiao-Qing Zhang
Keyword(s):  
Dynamic Characteristics ◽  
Reynolds Equation ◽  
Flow Model ◽  
Thrust Bearing ◽  
Slip Flow ◽  
Continuum Flow ◽  
Slip Flow Regime ◽  
Small Perturbation Method ◽  
Volume Method ◽  
The Continuum

The effects of gas-rarefaction on dynamic characteristics of micro spiral-grooved-thrust-bearing are studied. The Reynolds equation is modified by the first order slip model, and the corresponding perturbation equations are then obtained on the basis of the linear small perturbation method. In the converted spiral-curve-coordinates system, the finite-volume-method (FVM) is employed to discrete the surface domain of micro bearing. The results show, compared with the continuum-flow model, that under the slip-flow regime, the decrease in the pressure and stiffness become obvious with the increasing of the compressibility number. Moreover, with the decrease of the relative gas-film-thickness, the deviations of dynamic coefficients between slip-flow-model and continuum-flow-model are increasing.

scholarly journals Stagnation point bionanofluid slip flow model: Sensitivity analysis

2021 ◽  
Vol 60 (6) ◽  
pp. 5227-5243
Author(s):  
Sze Qi Chan ◽  
Fazlina Aman ◽  
Syahira Mansur
Keyword(s):  
Sensitivity Analysis ◽  
Stagnation Point ◽  
Flow Model ◽  
Slip Flow ◽  
Model Sensitivity
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