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My first PDE

Posted Aug 7, 2014, 11:16 a.m. EDT Version 4.4 3 Replies

Oliver Possnert
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Hi , we are two undergraduates students who are trying to solve a system of five PDE's in COMSOL.
We have been able to do this in MATLAB but are unable to achieve this in COMSOL. To start of we tried to implement a simple diffusion PDE using the coefficient PDE solver. We have troubles simulating our system. Can someone explain why?
SPECIFICS
-Geometry: 100 mm^2
-Coefficients: C = 4.9*10^-6, da = -1, all other 0.
-intial value: 1*10^7
- boundary: Dirchlets r = 0 for all
- normal mesh, fine
Then we used the study tool (time dependent) and solved for time (0,1,10).
Error: "Differential-algebraic equation encountered. Use Singular mass matrix = Yes.."
3 Replies Last Post Sep 5, 2014, 5:36 p.m. EDT
Mehrdad Shahmohammadi Beni
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Posted: 1 decade ago Aug 12, 2014, 3:13 a.m. EDT
Hi

Can you give me more info about your problem, If it is possible show me your PDEs that you would like to solve so I can check step by step.

Regards.

Ben.
Hi Can you give me more info about your problem, If it is possible show me your PDEs that you would like to solve so I can check step by step. Regards. Ben.
Oliver Possnert
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Posted: 1 decade ago Aug 12, 2014, 4:34 a.m. EDT
Hi Ben,

Thank you for your interest in our problem. As for now we have managed to get some guidence from elsewhere but it can't hurt to get a second look at it! I have attached a PDF-document in this reply which is explaining our model and containing our PDE's.

Best regards,

Oliver
Hi Ben, Thank you for your interest in our problem. As for now we have managed to get some guidence from elsewhere but it can't hurt to get a second look at it! I have attached a PDF-document in this reply which is explaining our model and containing our PDE's. Best regards, Oliver
Trevor Davis
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Posted: 1 decade ago Sep 5, 2014, 5:36 p.m. EDT
Hi Oliver,

I am running into a similar problem with my PDE interface. What sort of answers did you get/where did you get them in solving your problem?

Thanks,
Trevor
Hi Oliver, I am running into a similar problem with my PDE interface. What sort of answers did you get/where did you get them in solving your problem? Thanks, Trevor

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