Numerical Analysis of Subambient Pressure Air Bearing Under Nanometer Spacings in Hard Disk Driver

Ultra thin film lubrication with nanometer spacings plays an important role in microscale fields such as MEMS, hard disk drives. The usual methods of gas dynamics are no longer applicable when the mean free path of gas molecules is not negligible in comparison with the characteristic length of flow field. In this paper, a new model based on rarefied gas dynamics suitable to arbitrary Knudsen numbers is established firstly. Then, an effective numerical method is developed to calculate the modified Reynolds equation for ultra thin gas film lubrication. The application to a typical case and numerical calculations using the modified Reynolds equations are performed with subambient pressure sliders. The numerical results show that the model and numerical method are valid for slider air bearing with nanometer spaces