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Two solver steps in time depend. study

Posted Aug 22, 2017, 1:36 p.m. EDT Version 5.3 2 Replies

Lawrence Renna
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I am running a time dependent study. When I try and run for long times, i.e. greater than 5 s, it does not converge. However, if I run a solver step until ~0.1 s and then feed that result in as the initial condition in a second step in the solver, I can run it to longer times, i.e. 100 s. The solutions seem reasonable.

My question is: Is this an appropriate method to getting a simulation to converge?

Thank you
2 Replies Last Post Aug 22, 2017, 2:09 p.m. EDT
Jeff Hiller COMSOL Employee

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Posted: 7 years ago Aug 22, 2017, 1:58 p.m. EDT
Hello Lawrence,
Please see my colleague's contribution to the following thread for an explanation why your model behaves differently depending on the end time.
www.comsol.com/community/forums/general/thread/108101
As that post suggests, you should be able to get convergence in a single solver step by adjusting the settings as he describes.
Best,
Jeff
Hello Lawrence, Please see my colleague's contribution to the following thread for an explanation why your model behaves differently depending on the end time. https://www.comsol.com/community/forums/general/thread/108101 As that post suggests, you should be able to get convergence in a single solver step by adjusting the settings as he describes. Best, Jeff
Lawrence Renna
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Posted: 7 years ago Aug 22, 2017, 2:09 p.m. EDT
Dear Jeff,

Thank you for directing me to this post.

Decreasing the "fraction of initial step" worked perfectly. I can now use a single solver step.

Best,
Lawrence
Dear Jeff, Thank you for directing me to this post. Decreasing the "fraction of initial step" worked perfectly. I can now use a single solver step. Best, Lawrence

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