Knudsen Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Knudsen number, abbreviated as Kn, a dimensionless number, is used in fluid dynamics to determine what type of analysis should be used to model an object moving through a fluid.  It is defined as the ratio of the molecular mean free path length to a representative physical length scale.  This calculation determines the Knudsen number, the length or the lambda value based on your inputs.


Knudsen number calculator


Knudsen Number formula

\(\large{ Kn = \frac{ \lambda }{ l } }\)   


\(\large{ Kn }\) = Knudsen number

\(\large{ l }\) = length

\(\large{ \lambda }\) (Greek symbol lambda) = mean free path


Tags: Equations for Fluid Calculators