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Poisson and Nernst-Planck equation coupling
Posted 10 apr 2014, 22:16 GMT-4 Version 4.3b 4 Replies
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This is a very simple case. In my problem, I focus on the concentration in the dilute solution with applied electric field. The electric potential allied on the two electrodes are stationary. No reaction or flux in the system. The concentration of the solution is 1M, electric potential difference between two electrode is 10V.
Since this is a stationary problem, I set 1-D(just a line) with two physics, poisson equation and NP Equation, However, I can not get the reasonable plot, so how can I get the plot of the concentration vs position.
My model is attached.
Many thanks
Attachments:
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Also, your interval is 1 m long, which makes no sense, i.e. the thickness of the double layer is usually of the order of nanometers (in 1.0 mM solution 10 nm).
Since you have no flux, ionic concentrations follow Boltzmann distribution, and the source term in the Poisson equation becomes -2*c_bulk*sinh(zF/RT*u). You cannot use Nernst-Planck equation because that assumes electroneutrality which contradicts with the Poisson equation.
The problem is also rather stiff, i.e. there are stability issues in the solution.
Attached my file with the boundary condition V(x=0) = 100 mV.
BR
Lasse
Attachments:
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Thanks for your help and I download your attachment. However I can not open it since my COMSOL version is 4.3b. I hope to understand this problem from your model, can you send me the screenshots or details in docs? Really appreciate it!
Best regards,
Larry
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Thanks for your help and I download your attachment. However I can not open it since my COMSOL version is 4.3b. I hope to understand this problem from your model, can you send me the screenshots or details in docs? Really appreciate it!
Best regards,
Larry
Please login with a confirmed email address before reporting spam
Lasse
Attachments: