Turbomolecular Pump

Application ID: 46911

The Free Molecular Flow interface, available in the Molecular Flow Module, is an efficient tool for modeling extremely rarefied gases when the gas molecules move much faster than any geometric entities in the domain. For turbomolecular pumps, in which the blades move at speeds comparable to the thermal speed of the gas molecules, a Monte Carlo approach is needed.

In this example, the trajectories of gas molecules are computed in the empty space between two rotating blades of a turbomolecular pump. The model uses the Rotating Frame feature, which applies centrifugal and Coriolis forces to the particles, allowing the trajectories to be computed in a noninertial frame of reference that moves with the rotating blades. The effect of the blade velocity on the compression factor is shown using a parametric sweep.

This model example illustrates applications of this type that would nominally be built using the following products: