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Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Knudsen Number

Knudsen number ( \(Kn\) ) (dimensionless number) is defined as the ratio of the molecular mean free path length to a representative physical length scale.

Knudsen Number FORMULA

:(Kn

\( Knudsen \; number    \;=\;    \frac{  mean \; free \; path  }  { length }\)

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

Where:

\(Kn\) = Knudsen number

\( \lambda \) (Greek symbol lambda) = mean free path

\( l\) = length

Solve for:

\(\lambda =  Knl \)

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