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error in Frequency-Transient Simulation
Posted Dec 31, 2013, 12:49 p.m. EST Studies & Solvers Version 4.4 3 Replies
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Happy new year! everyone
recently i have maked a Frequency-Transient Simulation and got a error infomation:
"Failed to find consistent initial values.
Last time step is not converged."
the detail in "warnings" information is:
"In segregated group 2:
There was an error message from the linear solver.
Divergence of the linear iterations."
how can i solve this problem and improve my model? thanks for your help
recently i have maked a Frequency-Transient Simulation and got a error infomation:
"Failed to find consistent initial values.
Last time step is not converged."
the detail in "warnings" information is:
"In segregated group 2:
There was an error message from the linear solver.
Divergence of the linear iterations."
how can i solve this problem and improve my model? thanks for your help
3 Replies Last Post Jan 16, 2014, 9:01 p.m. EST
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Posted:
1 decade ago
Hi,
without the model this is difficult to answer - so just some general hints:
it looks like the linear iterative solver that is used for group 2 did not converge, either by reaching the maximum number of iterations or the behaviour of the error is not contractive (will never converge even if you increase the max number of iterations) - you can see this in the convergence plot (growing=divergence). The reason for this can be e.g. non-optimal solver settings, inconsistent initial values or modeling problems. As a start, if your RAM allows, the easiest thing to try is to switch to a direct solver in group 2 and see if it solves the block.
More detailed tips and tricks can be found in our knowledgebase:
www.comsol.com/search/?subset=support_knowledge_base&s=convergence
or in the COMSOL Reference Manual on page 135ff (Analyzing Model Convergence and Accuracy).
without the model this is difficult to answer - so just some general hints:
it looks like the linear iterative solver that is used for group 2 did not converge, either by reaching the maximum number of iterations or the behaviour of the error is not contractive (will never converge even if you increase the max number of iterations) - you can see this in the convergence plot (growing=divergence). The reason for this can be e.g. non-optimal solver settings, inconsistent initial values or modeling problems. As a start, if your RAM allows, the easiest thing to try is to switch to a direct solver in group 2 and see if it solves the block.
More detailed tips and tricks can be found in our knowledgebase:
www.comsol.com/search/?subset=support_knowledge_base&s=convergence
or in the COMSOL Reference Manual on page 135ff (Analyzing Model Convergence and Accuracy).
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Posted:
1 decade ago
there are two segregated steps in the list of segregated, does segregated group 2 mean the second step?
thank you for your answer
thank you for your answer
Hi,
without the model this is difficult to answer - so just some general hints:
it looks like the linear iterative solver that is used for group 2 did not converge, either by reaching the maximum number of iterations or the behaviour of the error is not contractive (will never converge even if you increase the max number of iterations) - you can see this in the convergence plot (growing=divergence). The reason for this can be e.g. non-optimal solver settings, inconsistent initial values or modeling problems. As a start, if your RAM allows, the easiest thing to try is to switch to a direct solver in group 2 and see if it solves the block.
More detailed tips and tricks can be found in our knowledgebase:
www.comsol.com/search/?subset=support_knowledge_base&s=convergence
or in the COMSOL Reference Manual on page 135ff (Analyzing Model Convergence and Accuracy).
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi,
i have tried to switch to a direct solver, but it needed too much memory and i had to stop it at the end.
can you tell me more about how to debug the model or the skill to find out the problems?and i'm very glad, if you have time to take a look at my model and give me some suggestions.
thank you very much
i have tried to switch to a direct solver, but it needed too much memory and i had to stop it at the end.
can you tell me more about how to debug the model or the skill to find out the problems?and i'm very glad, if you have time to take a look at my model and give me some suggestions.
thank you very much
Hi,
without the model this is difficult to answer - so just some general hints:
it looks like the linear iterative solver that is used for group 2 did not converge, either by reaching the maximum number of iterations or the behaviour of the error is not contractive (will never converge even if you increase the max number of iterations) - you can see this in the convergence plot (growing=divergence). The reason for this can be e.g. non-optimal solver settings, inconsistent initial values or modeling problems. As a start, if your RAM allows, the easiest thing to try is to switch to a direct solver in group 2 and see if it solves the block.
More detailed tips and tricks can be found in our knowledgebase:
www.comsol.com/search/?subset=support_knowledge_base&s=convergence
or in the COMSOL Reference Manual on page 135ff (Analyzing Model Convergence and Accuracy).
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