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General question about interpretation of boundary condition at interior boundaries

Posted 2013年6月28日 GMT-4 04:04 Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.3b 2 Replies

Jan Nitzbon
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Dear Comsol-community,

I am simulating a diffusion equation using the "Coefficient Form PDE" from the mathematics interface in a 2D domain. There is an interior boundary at which I want to set a "Flux/Source"-BC. I am now wondering how this is exactly interpretated by Comsol.
In the User Guide (to version 4.2a) on page 751 the situation that fits to my problem is described. I want to set the BC that is described by the equation
-n1*F1-n2*F2=g-qu (ni=normal vector, Fi=flux vector).
Unfourtunately from the explanation in the Guide I did not exactly understand whether Comsol by default interpretates the interior boundaries as described by this equation OR if I need to implement this in a special way. In the latter case, how would I need to implement this BC in version 4.3b?

Thank you in advance!

Best regards
Jan Nitzbon
2 Replies Last Post 2013年11月4日 GMT-5 15:10
COMSOL Moderator

Hello Jan Nitzbon

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Marco Zanoni
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Posted: 1 decade ago 2013年10月23日 GMT-4 12:13
Hi,

I have the same problem. I'm trying to apply a constant heat flux, for example
-n(Gamma)=g where g=41000[W/m^2].

But I cannot get this work properly.

Did you find any answer for your problem?

Thanks.

Marco
Hi, I have the same problem. I'm trying to apply a constant heat flux, for example -n(Gamma)=g where g=41000[W/m^2]. But I cannot get this work properly. Did you find any answer for your problem? Thanks. Marco
Jan Nitzbon
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Posted: 1 decade ago 2013年11月4日 GMT-5 15:10
I think in my case it worked out to take the "normal" BC "Heat/Flux" at the interior boundary. Comsol interpreted that as in the equation I mentioned in my first post. However, if I rember right, I had a lot of problems with finding the right way to implement the BC. Finally I figured it out because I was able to compare my results to theoretical predictions.

Good luck for your problem!
I think in my case it worked out to take the "normal" BC "Heat/Flux" at the interior boundary. Comsol interpreted that as in the equation I mentioned in my first post. However, if I rember right, I had a lot of problems with finding the right way to implement the BC. Finally I figured it out because I was able to compare my results to theoretical predictions. Good luck for your problem!

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