# Fourier Number (mass)

## Description

The Fourier number (Fo) or Fourier modulus, is a dimensionless number that characterizes heat conduction. It is the ratio of diffusive/conductive transport rate by the quantity storage rate and arises from non-dimensionalization of the heat equation. The transported quantity is usually either heat or matter (particles). For transient mass transfer by diffusion, there is an analogous mass Fourier Number to the thermal Fourier number.

Related formulas## Variables

Fo_{m} | Fourier Number (dimensionless) |

D | The Diffusivity (m^{2}/s) |

t | The characteristic timescale (s) |

L | The length scale of interest (m) |