Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

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

Please login with a confirmed email address before reporting spam

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 2019/02/22 8:37 GMT-5
Walter Frei COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 5 years ago 2019/02/22 8:37 GMT-5

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,

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.