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.

An Evaluation of the Average Flow Model [1] for Surface Roughness Effects in Lubrication

1980 ◽  
Vol 102 (3) ◽  
pp. 360-366 ◽  
Author(s):  
J. L. Teale ◽  
A. O. Lebeck
Keyword(s):  
Surface Roughness ◽  
Flow Model ◽  
Two Dimensional ◽  
Roughness Effects ◽  
Important Conclusion ◽  
Average Flow ◽  
One Dimensional ◽  
Dimensional Flow ◽  
Two Dimensional Flow ◽  
Average Flow Model

The average flow model presented by Patir and Cheng [1] is evaluated. First, it is shown that the choice of grid used in the average flow model influences the results. The results presented are different from those given by Patir and Cheng. Second, it is shown that the introduction of two-dimensional flow greatly reduces the effect of roughness on flow. Results based on one-dimensional flow cannot be relied upon for two-dimensional problems. Finally, some average flow factors are given for truncated rough surfaces. These can be applied to partially worn surfaces. The most important conclusion reached is that an even closer examination of the average flow concept is needed before the results can be applied with confidence to lubrication problems.

Pressure and Shear Flow in a Rough Hydrodynamic Bearing, Flow Factor Calculation

1997 ◽  
Vol 119 (3) ◽  
pp. 549-555 ◽  
Author(s):  
L. Lunde ◽  
K. To̸nder
Keyword(s):  
Finite Element Method ◽  
Surface Roughness ◽  
Finite Element ◽  
Shear Flow ◽  
Reynolds Equation ◽  
Flow Model ◽  
The Finite Element Method ◽  
Average Flow ◽  
Hydrodynamic Bearing ◽  
Average Flow Model

The lubrication of isotropic rough surfaces has been studied numerically, and the flow factors given in the so-called Average Flow Model have been calculated. Both pressure flow and shear flow are considered. The flow factors are calculated from a small hearing part, and it is shown that the flow in the interior of this subarea is nearly unaffected by the bearing part’s boundary conditions. The surface roughness is generated numerically, and the Reynolds equation is solved by the finite element method. The method used for calculating the flow factors can be used for different roughness patterns.

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).

A slip model for gas lubrication based on an effective viscosity concept

2003 ◽  
Vol 217 (3) ◽  
pp. 187-195 ◽  
Author(s):  
Y. H. Sun ◽  
W. K. Chan ◽  
N. Y. Liu
Keyword(s):  
Boltzmann Equation ◽  
Effective Viscosity ◽  
Microelectromechanical Systems ◽  
Second Order ◽  
Slip Effect ◽  
Slip Model ◽  
Order Model ◽  
First Order ◽  
Linearized Boltzmann Equation ◽  
Gas Lubrication

Gas lubrication theory is used widely in microelectromechanical systems such as microbearings, micropumps and microvalves. Because of microsize or even nanosize geometries, rarefaction and compressible effects will have an impact on the viscosity on flow in these devices. In this paper, the concept of effective viscosity is taken into account for non-continuum flows. The influence of the effective viscosity is incorporated in the analytical solutions of plane Poiseuille flow and flow in inclined channels. The results obtained in the slip, transition and free molecular regimes are compared with the existing first-order and second-order slip models and the linearized Boltzmann equation. It was found that the first-order model underestimates the slip effect while the second-order model overestimates the slip effect. The results obtained from the proposed slip model provide a more accurate approximation to the linearized Boltzmann equation.

A Database for Interpolation of Poiseuille Flow Rates for High Knudsen Number Lubrication Problems

1990 ◽  
Vol 112 (1) ◽  
pp. 78-83 ◽  
Author(s):  
S. Fukui ◽  
R. Kaneko
Keyword(s):  
Boltzmann Equation ◽  
Knudsen Number ◽  
Flow Rate ◽  
Poiseuille Flow ◽  
Interpolation Method ◽  
Numerical Calculations ◽  
Flow Rates ◽  
Lubrication Equation ◽  
Linearized Boltzmann Equation ◽  
Rapid Calculation

This paper proposes the use of a Poiseuille flow rate database for rapid calculation of a generalized lubrication equation for high Knudsen number gas films. The database is created by numerical calculations based on the linearized Boltzmann equation. The proposed interpolation method is verified to reduce calculation time to several tenths of that required to perform rigorous calculations with the same accuracy.

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