Continuum model for Couette-Poiseuille flow in a drag molecular pump
  A continuum one-dimensional model of the plane Couette-Poiseuille flow is developed to describe the pressure distribution in a drag stage of molecular pump of either the Gaede or Holweck type. In spite of its simplicity and approximate nature the model provides a good qualitative representation of the drag pump operation in the whole range of the regimes from the continuum to free molecular ones. 
Petr A. Skovorodko