A numerical calculation methodology applying the alternating direction implicit (ADI) scheme is derived for the solution to the averaged Reynolds equation in volving flow factors resulting from Boltzmann molecular free flow. This methodology features the transformation of the dependent variable in the Reynolds equation from the pressure to the product of the averaged pressure times the averaged spacing, in combination with the determination of the flow factor using averaged spacing. This technique can be used to obtain the dynamic characteristics of compressible lubricating films incurring surface roughness effects under rarefaction conditions. In applying this method to a head slider in practical use, transient responses resulting from the slider flying over a bump and incurring surface roughness effects are compared for three roughness pattern cases. Longitudinal roughness effects are found to appear in the transient response with regard to a simultaneous decrease in the natural frequency and in the damping speed. Conversely, moving transverse roughness affects the response inversely, and stationary transverse roughness influences it only slightly.

Issue Section:
Research Papers
Topics:
Flow (Dynamics), Surface roughness, Transients (Dynamics), Pressure, Damping
1.
Bhushan
B.
, and
Tonder
K.
,
1989
, “
Roughness-Induced Shear- and Squeeze-Film Effects in Magnetic Recording—Part 1; Analysis
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
111
, No.
2
, pp.
222
–
227
.
2.
Crone, R. M., John, S. M., Bhushan, B., and Karis, T. E., 1990, “Transient Behavior of a Rough Slider Dropped Over a Rough Rigid-Disk Surface,” ASME Press Adv. Info. Storage Syst., Vol. 1, pp. 189–212.
3.
Fukui, S., Kogure, K., and Mitsuya, Y., 1985, “Dynamic Characteristics of Flying-Head Slider on Running Wavy Disk,” ASLE Special Publication No. SP-19, pp. 52–58.
4.
Fukui
S.
, and
Kaneko
R.
,
1988
, “
Analysis of Ultra-Thin Gas Film Lubrication Based on Linearized Boltzmann Equation
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
110
, NO.
2
, pp.
253
–
262
.
5.
Hayashi, T., and Ohkubo, T., 1991, “Comparison of the Direct Numerical Solution and the Perturbation Solution in the Dynamic Analysis of a Flying Head Slider for Magnetic Disk Storage Operation at Very Low Spacing,” ASME Press Adv. Info. Storage Syst., Vol. 2, pp. 113–125.
6.
Mitsuya
Y.
,
Ohkubo
T.
, and
Ota
H.
,
1989
, “
Averaged Reynolds Equation Extended to Gas Lubrication Possessing Surface Roughness in the Slip Flow Regime: Approximate Method and Confirmation Experiments
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
111
, No.
3
, pp.
495
–
503
.
7.
Mitsuya
Y.
,
1984
, “
A Simulation Method for Hydrodynamic Lubrication of Surfaces with Two-Dimensional Isotropic or Anisotropic Roughness Using Mixed Average Film Thickness
,”
Bulletin of JSME
, Vol.
27
, No.
231
, pp.
2036
–
2044
.
8.
Mitsuya, Y., and Hayashi, T., 1990, “Transient Response of Head Slider When Flying Over Textured Disk Media,” Proc. Japan Int. Tribal. Conf., No. 3, pp. 1941–1946.
9.
Mitsuya
Y.
, and
Ota
H.
,
1991
, “
Stiffness and Damping of Compressible Lubricating Films Between Computer Flying Heads and Textured Media: Perturbation Analysis Using the Finite Element Method
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
113
, No.
4
, pp.
819
–
827
.
10.
White
J. W.
, and
Nigam
A.
,
1980
, “
A Factored Implicit Scheme for the Numerical Solution of the Reynolds Equation at Very Low Spacing
,”
ASME JOURNAL OF LUBRICATION TECHNOLOGY
, Vol.
102
, No.
1
, pp.
80
–
85
.
11.
Zhu, L. Y., and Bogy, D. Y., 1989, “Head-Disk Spacing Fluctuation Due to Disk Topography in Magnetic Recording Hard Disk Files,” STLE Special Publication No. SP-26, pp. 160–167.
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