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COMSOL Fuel cell tutorials: ERRORS & WARNINGS IN SOLVER

Posted 4 avr. 2011, 19:17 UTC−4 Low-Frequency Electromagnetics, Studies & Solvers Version 4.0a 2 Replies

Sehribani Ulusoy
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Hi,

I have just started to use COMSOL Multiphysics, and Fuel Cell and Batteries Module. I am doing the tutorials related to fuel cells and I am having problems with the solution part.

Fuel cell tutorials that I have completed are
"Species Transport in the Gas Diffusion Layers of a PEM" &
"Mass Transport and Electrochemical Reaction in a Fuel Cell Cathode".

For both of them, I couldn't get any results. I have checked with the original .mph files, although all my steps are the same , I am getting error and warnings.

For the first one(GDL), the error is:

"Failed to find a solution.
Maximum number of Newton iterations reached.
Returned solution has not converged."

For the second one(Cathode), the warnings in the following order are:

"Ill-conditioned preconditioner. Increase factor in error estimate to 155.4718301037104"
"Ill-conditioned preconditioner. Increase factor in error estimate to 256.6441852180479"
"Ill-conditioned preconditioner. Increase factor in error estimate to 269.1247545481101"
"Ill-conditioned preconditioner. Increase factor in error estimate to 221.9807080541324"

I hope you can help me about this issues. I am attaching the .mph files I have done. The other files, you can find using the following links:

www.comsol.com/showroom/documentation/model/260/
www.comsol.com/showroom/documentation/model/458/

Thanks a lot in advance.

SU



2 Replies Last Post 31 mai 2011, 14:28 UTC−4
Magnus Ringh COMSOL Employee

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Posted: 1 decade ago 5 avr. 2011, 04:16 UTC−4
Hi,

The GDL model seems to be missing an Inflow condition at boundary 22 for the Transport of Concentrated Species for the cathode.

In general, these fuel cell models are fairly complex multiphysics models with many interacting physics and variables, so it might be better to start with some simpler examples to get to know the software.

Best regards,
Magnus Ringh, COMSOL
Hi, The GDL model seems to be missing an Inflow condition at boundary 22 for the Transport of Concentrated Species for the cathode. In general, these fuel cell models are fairly complex multiphysics models with many interacting physics and variables, so it might be better to start with some simpler examples to get to know the software. Best regards, Magnus Ringh, COMSOL
Tyler
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Posted: 1 decade ago 31 mai 2011, 14:28 UTC−4
Hi Magnus,

Do you have any advice on the "Ill-conditioned preconditioner" warning? I'm getting it in a 3D model using MF. The warning recommends to increase the error estimate to a high value, is that all that may be done, or is there likely some other fundamental problem with my model.

model: in MF, edge current applied, edges form a helical structure. A cylindrical volume in located at its centre. splitting the volume into two cylinders, model solves fine with default iterative parameters. Splitting the volume into four pieces, throws ill-coniditioned warning.

thanks!
Hi Magnus, Do you have any advice on the "Ill-conditioned preconditioner" warning? I'm getting it in a 3D model using MF. The warning recommends to increase the error estimate to a high value, is that all that may be done, or is there likely some other fundamental problem with my model. model: in MF, edge current applied, edges form a helical structure. A cylindrical volume in located at its centre. splitting the volume into two cylinders, model solves fine with default iterative parameters. Splitting the volume into four pieces, throws ill-coniditioned warning. thanks!

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