Abstract
We analyze rarefied gas flows in lubricating films that form between the read/write head and rotating recording medium in computer hard drives. A modified slip-corrected Reynolds lubrication equation is derived for arbitrary Knudsen numbers using the Navier-Stokes equation with consistent slip boundary conditions and modified physical coefficients. In particular, we present results of velocity profiles, pressure distribution and load capacity for various slider bearing configurations. An empirical model for the velocity distribution is developed by studying the Poiseuille and Couette flow components of the lubricating film. Important lubrication characteristics such as the pressure distribution and load capacity are obtained directly from numerical solutions of the modified Reynolds equation. In addition, we outline a method to accurately predict the shear drag forces induced by air resistance to the track-access-motion of the sliders. The new model is validated by comparisons with numerical solutions of the generalized lubrication equation based on the two-dimensional linearized Boltzmann equation and Direct Simulation Monte Carlo (DSMC) results available in the literature. The model predicts the velocity profiles, pressure distribution, load capacity and skin friction with good accuracy for a wide range of Knudsen numbers for low subsonic compressible flows. However it exhibits some physical limitations in the free molecular flow regime, due to its use of a Poiseuille flowrate database obtained via the solution of a two- dimensional Boltzmann equation.
Bahukudumbi, Pradipkumar (2002). A phenomenological model for rarefied gas flows in thin film slider bearings. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2002 -THESIS -B345.