Knudsen Number

The Knudsen number (Kn) is a dimensionless number defined as the ratio of the molecular mean free path length to a representative physical length scale. This length scale could be, for example, the radius of the body in a fluid. The number is named after Danish physicist Martin Knudsen (1871–1949).

Read more about Knudsen Number:  Definition, Relationship To Mach and Reynolds Numbers in Gases, Application

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