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4.3b, AC/DC, Material Problem. Different Results on 2 Computer.
Posted 7 ago 2014, 07:47 GMT-4 Low-Frequency Electromagnetics, Materials, Results & Visualization Version 4.3b, Version 4.4 3 Replies
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iam new to Comsol and iam having some Problems. For my Bachelors Thesis iam looking into the resistivity of Concrete.
I createt a Cone in version 4.3b that exists of Concrete with two electrodes of Steel at the bottom and top.
I also created the exact same Cone in Verion 4.4.
Iam using Surface Average and Volume Integration to get the Current Density and Current. While using V4.4 iam getting the right results. Checked this with hand calculations.
While using comsol 4.3b iam getting really weird results. Very different from what the results should be like.
I made sure both Models wehere created the same.
After this i changed te concrete to Titanium just to see what happens. Again i let Comsol calculate Current Density and Current. Both V4.4 and V4.3b show the same results. Like its supposed to.... i guess.
I suspect the Material Concrete to be the Probleme. I checked all Material Propertys but i could not find any difference.
I would be really nice if someone of you could help me out.
I can post the files here if needed!
Thank you!
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if you post the models I can have a short look. Without that I cannot say what is causing this effect.
Best
Hinrich Arnoldt
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here are the Models that i created.
Vergleich4.3bConcrete and
Vergleich4.4Concrete show the difference in the results while using concrete.
Vergleich4.3bTitanium and
Vergleich4.4Titanium show that in both Versions i get the same results while using different Materials.
I hope you understand what iam talking about. It is somewhat confusing...
Thank you
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the reason for this effect is the different conductivity of the materials combined with new solver settings in Version 4.4.
If you plot ec.normJ in your Concrete 4.3b Model you will see that the solution is wrong. There are extremely high values of ec.normJ around. If you look into the solvers you will find that an iterative solver is applied which seems to have problems with the highly different conductances of steel and concrete. I have set the solver to direct and the solution is obtained fastly and it is correct, too.
Best
Hinrich Arnoldt