A new molecular gas lubrication theory suitable for head-disk interface modeling

A rigorous generalized Reynolds equation, which governs gas lubrication dyn amics at the head disk interface (HDI), has been derived from the Bhatnagar -Gross-Krook kinetic equation. Rarefaction effects for arbitrary surface ac commodation coefficients are incorporated by calculating both the Couette a nd Poiseuille flow rates. New flow rate databases have been generated, whic h correct and extend the erroneous existing databases currently used for HD I simulations. Furthermore, a new set of system equations for the pitch and roll angles has been constructed by including shear stress changes due to rarefaction phenomena, which becomes critically important in estimating sli der dynamics at ultralow flying heights. (C) 1999 American Institute of Phy sics. [S0021-8979(99)38408-5].