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not converged in spite of the low error value

Posted 21 janv. 2017, 11:59 UTC−5 Studies & Solvers Version 5.2, Version 5.2a 2 Replies

Michael Potter
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Hi,
I'm modeling a reactor with turbulent fluid flow and heat transfer and got really confused. The Nonlinear
solver reaches the error value lower than 1e-10 however the solver dose not stop the calculation. Could any one assist me with this problem?
2 Replies Last Post 26 janv. 2017, 11:54 UTC−5
Henrik Sönnerlind COMSOL Employee

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Posted: 8 years ago 24 janv. 2017, 02:58 UTC−5
Hi,

There are several criteria which need to be fulfilled for a solution to be considered as converged.

Maybe the discussions in

www.comsol.com/community/forums/general/thread/35375

can be of some help.

Regards,
Henrik
Hi, There are several criteria which need to be fulfilled for a solution to be considered as converged. Maybe the discussions in https://www.comsol.com/community/forums/general/thread/35375 can be of some help. Regards, Henrik
Michael Potter
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Posted: 8 years ago 26 janv. 2017, 11:54 UTC−5
Hi ,
Dear Henrik,
Thank's for your reply.
I read that page and your explanation completely.
The damping factor for my case was descended.
I have three questions:
1- What should be done to prevent this happening ?
2- Does setting termination criteria to be "solution or residual" help solve this problem ?
3- I want to know what is the reason for the statement :
"it is required that the damping factor in the Newton solver is 1 before the solution is accepted"
Could you introduce some references for further study ?

Best regards
Michael Potter
Hi , Dear Henrik, Thank's for your reply. I read that page and your explanation completely. The damping factor for my case was descended. I have three questions: 1- What should be done to prevent this happening ? 2- Does setting termination criteria to be "solution or residual" help solve this problem ? 3- I want to know what is the reason for the statement : "it is required that the damping factor in the Newton solver is 1 before the solution is accepted" Could you introduce some references for further study ? Best regards Michael Potter

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