Ultra-thin gas squeeze film characteristics for infinitely large squeeze number

In this study, the characteristics of ultra-thin gas films are analyzed asymptotically for infinite squeeze number using the molecular gas film lubrication equation with coupled roughness and rarefaction effects taken into consideration. The governing equation of the internal region was obtained by a time averaged technique, and the boundary conditions were obtained numerically from the matching conditions near the boundaries. Two new functions, H and H^-1, were proposed for deriving the matching equation near the boundary. Finally, the characteristics of squeeze film bearings with infinite width were analyzed for various roughness parameters (Peklenik number, standard deviations of the composite roughness, and roughness orientation angles), rarefaction parameter (Knudsen number), and operation conditions (excursion ratio).