# Knudsen number (For a Boltzmann gas)

## Description

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. For a Boltzmann gas Knudsen number is depended on the thermodynamic temperature, the particle hard shell diameter and the total pressure.

Related formulas## Variables

K_{n} | Knudsen number (dimensionless) |

k_{B} | Boltzmann constant |

T | The thermodynamic temperature (K) |

π | pi |

d | The particle hard shell diameter (m) |

P | The total pressure, (Pa) |

L | The representative physical length scale (m) |