Pressure dependence of the diffusion coefficient

Description

Diffusivity or diffusion coefficient is a proportionality constant between the molar flux due to molecular diffusion and the gradient in the concentration of the species (or the driving force for diffusion).

For self-diffusion in gases at two different pressures (but the same temperature), a empirical equation has been suggested.

Related formulas

Variables

DP1diffusion coefficient at pressure 1 (dimensionless)
DP2diffusion coefficient at pressure 2 (dimensionless)
ρP2gas mass density at pressure 2 (dimensionless)
ρP1gas mass density at pressure 1 (dimensionless)