Diffusion Equaton Fluent
 

Hi

I want to model a pure mass diffusion equation (laplace Equation) with certain concentration and the inlet and outlet of a cube geometry.

How can I do that without having a concentration gradient from outlet toward the centre of the geometry.What should be the boundary conditions?

How can I calculate the molar diffusion flux at the inlet. The flux part of the Fluent can not be use because I set velocity as zero in the boundary conditions.

Thanks,