Molecular gas film lubrication theory in free moleculer region : Effects of accomodation coefficients

Abstract

For examining molecular gas film lubrication (MGL) characteristics in several nanometers, free molecular MGL equation, which employs Poiseuille flow rate and shear stress coefficient for free molecular flow region, is established considering surface accommodation effects and calculated the characteristics of plane inclined slider and step slider with accommodation coefficients of disk and slider, α_0 and α_1,as parameters. As the minimum spacing decreases, pressures and shear stresses by the use of conventional MGL equation and the free molecular MGL equation become close each other, which means free molecular MGL equation is applicable for the nanometer region. Moreover, differences among any flow rates in Poiseuille flows become diminished, as the minimum spacings decreases and bearing number increases.