Abstract
Fundamental aspects for low- and medium-vacuum regions are described. Some long-standing problems, such as slip flow, pumpdown curve for viscous flow region, and vacuum drying are presented. The importance of slip velocity at a pipe wall for the Knudsen number between 0.01 and 0.1 is enlightened. A numerical result for a pumpdown curve with a pressure dependent conductance in the viscous flow regime was presented with an emphasis on a t−1 pressure decrease. In addition, vacuum drying process is modeled with a water containing capillary and pressure dependent mass flow is discussed.
