# Knudsen Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

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

## FORMULA

:(Kn$$Kn = \frac{ \lambda }{ l }$$

Where:

$$Kn$$ = Knudsen Number

$$\lambda$$ = mean free path

$$l$$ = length

Solve for:

$$\lambda = Knl$$

$$l = \frac{ \lambda }{ Kn }$$