# Effective Diffusivity in Porous Media

Effective diffusivity in porous media, abbreviated as \( D_e \), is the adequate dispersion of gas or liguid through the voids of soil.

## Effective diffusivity in porous media formula

\(\large{ D_e = \frac{ D \; n \; \delta }{ \tau } }\) |

### Where:

Units |
English |
Metric |

\(\large{ D_e } \) = effective diffusivity | \(\large{ \frac{ft^2}{sec} }\) | \(\large{ \frac{m^2}{s} }\) |

\(\large{ D } \) = diffusion coefficient in gas or liquid filling the pores | \(\large{\frac{ft^2}{sec}}\) | \(\large{\frac{m^2}{s}}\) |

\(\large{ n }\) = porosity available for transportation | \(\large{dimensionless}\) | |

\(\large{ \delta }\) (Greek symbol delta) = constrictivity | \(\large{dimensionless}\) | |

\(\large{ \tau } \) (Greek symbol tau) = tortuosity | \(\large{dimensionless}\) |

Tags: Soil Equations Geotechnical Equations Diffusion Equations