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Concentration profile problem

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I have a model of a charged capillary with negative charge on its walls. When calculating the electrolyte flux across is, I reach incorrect concentration profiles outside the capillary, see attached images. This makes the flux and electric current discontinuous.

The physics is Laminar flow + Nernst-Planck-Poisson equation. Volume force within the capillary is

roo_e*dV/dx

where roo_e is the volume charge density. Capillary resides between 0 and 20 µm and aqueous diffusion boundary layers between -20...0 and 20...40 µm.

ConcProfile picture is for the cation (Na+).



0 Replies Last Post 21.11.2023, 07:12 GMT-5
COMSOL Moderator

Hello Lasse Murtomäki

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