Stress-density ratio slip-corrected Reynolds equation for ultra-thin film gas bearing lubrication

Abstract

The direct simulation Monte Carlo method is used to evaluate the improved slip boundary condition and slip-corrected Reynolds equation for gas lubrication in magnetic recording storage system. The study shows that in transition regime, the slip velocity is affected not only by shear stress, but also by density itself. In this ultra-thin film lubrication environment, the slip velocity has a linear relationship with the ratio of shear stress to density near the wall. This observation is particularly true when Knudsen number is around 1 or larger. Through this study, the authors have developed a new slip velocity model, named stress-density ratio model, particularly suitable to transition regime. Based on this novel model, a slip-corrected Reynolds equation is also derived and solved numerically. The stress-density ratio model is confirmed to offer a better applicability than the previous slip-flow models for modern computer magnetic storage device, where the Knudsen number of slider air bearing is in the range of unity or larger.