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Operator reacf

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I am trying to compute the current at an electrode by using the boundary integration. I do this by integrating the normal diffusive flux over the electrode boundary. However I was told that typing reacf(c) (c=concentration) would increase the accuracy of the calculation. Doing this gives me the wrong answer and anything else I try doesn't work. I haven't been able to find anything in the book that helps. Any help would be great.
Thanks

1 Reply Last Post 31 juil. 2009, 19:05 UTC−4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 2 decades ago 31 juil. 2009, 19:05 UTC−4
Hi
If you where somewhat more explicit about the physics you use and the model you would probably get more replies.

The ractf() function came on one of the last versions of COMSOL and is so far I have understood a simplified way to use the "weak form " integration over a boundary, which is more precise than a brute sum over edge elements.

I use it regularly for structural analysis it save me time from previous more tedious formula expressions and it works fine.

Now you have to apply the correct flux to it, I cannot tell if your "c" is the one, I propose that you look up "weak form" in the doc, then "current density integration" and search the discussion forum, there are already a few discussions around current from surface flux integration

Good luck
Ivar
Hi If you where somewhat more explicit about the physics you use and the model you would probably get more replies. The ractf() function came on one of the last versions of COMSOL and is so far I have understood a simplified way to use the "weak form " integration over a boundary, which is more precise than a brute sum over edge elements. I use it regularly for structural analysis it save me time from previous more tedious formula expressions and it works fine. Now you have to apply the correct flux to it, I cannot tell if your "c" is the one, I propose that you look up "weak form" in the doc, then "current density integration" and search the discussion forum, there are already a few discussions around current from surface flux integration Good luck Ivar

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