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Creeping, dilute, surface reacting flow - Negative concentration fixes?

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Hi all, new to COMSOL

I'm modeling creeping flow and transport of dilute species through a series of ribs, with an electrochemical reaction occuring at 10 mA/sqcm on the bottom surface of the under-rib flow. The initial concentration of the dilute species is 6.25 mM. It reacts away to form water. My model results show concentrations varying from 6.29 mM to -63.3 mM, but almost all the variation occurs within the last few millimeters of the outlet channels.

The inlet channel is the upper right face of the middle trunk, while the outlets are the two left faces of the outer drains (top and bottom of geometry)

I'm looking to either improve the calculations so that I don't get any negative concentrations, or limit the range of plotting values (to only show concentrations between 0 and 6.25 mM). Also, I'm looking to improve the visualization of the concentration distribution, so any tips there would be appreciated.

Please let me know if there is any additional information needed, thanks!



1 Reply Last Post Feb 22, 2019, 8:37 a.m. EST
Walter Frei COMSOL Employee

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Posted: 6 years ago Feb 22, 2019, 8:37 a.m. EST

Hello Isaac,

Regarding negative concentrations, please see: https://www.comsol.com/support/knowledgebase/952/

Best Regards,

Hello Isaac, Regarding negative concentrations, please see: https://www.comsol.com/support/knowledgebase/952/ Best Regards,

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