In this case, Kn is < 0.01. In addition, the term viscous flow is used if the product of pressure p
and diameter d of the components through which gas is flowing is p . d ≥ 6 . 10 -1 mbar . cm
for air.
In the case of viscous flow, a distinction is made between laminar and turbulent flow. Laminar
flow prevails at low flow speeds. At higher flow speeds, this changes to a turbulent flow [2].
The occurrence of turbulent flow is contingent upon the Reynolds number