Re: Coupling problem: Nernst-Planck equation with Poisson not converging

Hi Sri,

Thanks for your reply.
Yes, an electrolyte with two species is washed through the cell, entering through the inner tube and leaving through the outer tube. One of the species is transported through a transporter protein on a biomembran and is thus leaving the model (as this area is conntected to ground, no electrostatic force is built up. Now, with one species leaving, the concentration changes and therfore the space charge density, which over the Poisson-equation and and the defined space charge density should have influence on the migration-term in the nernst-planck equation as far as I understand. No external field or voltage is applied, my goal is to check whether these concentration gradients reach the electrode (next to the tubes) by migration in the presence of convection by the fluid. The diffusion term can be ignored in this case I think.

I had a look at the Tertiary current distribution, but it appears to neglect the self-induced migration term through the concentration change as well as sets up a electroneutrality condition, which is not applicable to my model.
I set up the model in accordance to the diffuse double layer model in the libraries....
I still don't understand why I don't get convergence in my case...

thanks for any help,
Raphael