The Knudsen Number refers to the dimensionless number. The Knudsen Number is defined as the ratio of the molecular mean free path length to a representative physical length scale. In short, the Knudsen Number refers to the ratio of the mean free path length of the molecules of a fluid to a characteristic length. It is used to describe the flow of low-density gases.
Knudsen Number :
Kn = λ/L
Mean Free Path :
λ = Kn*L
Representative Physical Length Scale :
L = λ/ Kn
Where,
Kn = Knudsen Number,
λ = Mean Free Path,
L = Representative Physical Length Scale.
This Advanced Online
Knudsen Number Calculator is used to calculate the ratio of the mean free path length of the molecules of a fluid to a characteristic length.
Example:
Calculate the Knudsen Number for the given details.
Mean Free Path (λ) = 25 m
Representative Physical Length Scale (L) = 20 m
Solution:
Apply Formula:
Kn = λ/L
Kn = 25/20
Kn = 1.25