Abstract
Ultra-thin gas squeeze film characteristics for finite squeeze numbers are examined by solving the molecular gas film lubrication (MGL) equation, which has a similar form to the conventional Reynolds-type lubrication equation but contains a flow rate coefficient and is valid for arbitrarily small spacings or for arbitrary Knudsen number. We quantitatively clarify by numerical computations that at thin film conditions below several micrometers, pressures generated by squeeze motions are lower than those of continuum flow case and therefore load-carrying capacities are smaller and depend upon film thickness because of the molecular gas effect. For example when the squeeze number is 10 and excursion ratio is 0.5, the load-carrying capacity at 0.1 μm is about one tenth of that at 1 μm.