Diffusivity can refer to:
- Diffusivity of heatThermal diffusivityIn heat transfer analysis, thermal diffusivity is the thermal conductivity divided by density and specific heat capacity at constant pressure. It has the SI unit of m²/s...
- Diffusivity of mass:
- Molecular diffusivity (often called "diffusion coefficient")
- Eddy diffusivityEddy diffusionEddy diffusion, eddy dispersion, or turbulent diffusion is any diffusion process by which substances are mixed in the atmosphere or in any fluid system due to eddy motion...
- Momentum diffusivity