Learning Forum

[zdfrankman]

I would like to change the diffusion coefficient of a fluid to model a species diffusion through a membrane. In the above image, the material window shows that there is no diffusion coefficient parameter on the materials database.
However, the handbook specifies that there should be a diffusion coefficient parameter to modify. Section 7.9.5. specifies "You will define or for each chemical species using the Create/Edit Materials Dialog Box.  Setup →  Materials. The diffusion coefficients have units of /s in SI units or /s in British units."

How do I input the parameters?
I have previously tried to simply alter the molecular weight and L-J characteristic length of the material, as these are components of the Einstein diffusion coefficient. However, altering these parameters had no impact on the diffusion rate in my simulation.

Thank you!

[Swathi V. V.]

Hi,

The mass diffusion coefficient for the species can be defined in the mass diffusivity input available in mixture material property.  Please see the screenshot below.