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Convergence and time step solver

Posted Dec 15, 2015, 1:53 a.m. EST Results & Visualization, Studies & Solvers Version 4.3 4 Replies

Badri Suhaini
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Hi all,
How's everyone? :D

Anyway,
Just want to know, what does that curvy distorted line at the end of the diagram shows?
Does it mean I have instability convergence? too large time step?

how do I solve this? I am getting singularity error everytime.

I followed "singularity.error" on the discussion forum and the comsol employee at the end of the discussion

Regards,
Badri

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4 Replies Last Post Dec 17, 2015, 2:12 a.m. EST
Krishnaswamy Veluswamy
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Posted: 9 years ago Dec 15, 2015, 1:31 p.m. EST
Hi,

Even I am facing facing the same issue with Time dependent optimization.

However, reducing the time step, doesnt going really affect the error, but you get the error after a prolonged time. (I got it like that), however for many it worked by reducing the time step.

Whatever the timestep you give in the solver, its just for post processing and it has nothing to do with the calculation (I hope so), as the comsol has inbuilt time stepping which will calculate at those time steps.

I still puzzled at the error. post me a msg if u get rid of this error.
Hi, Even I am facing facing the same issue with Time dependent optimization. However, reducing the time step, doesnt going really affect the error, but you get the error after a prolonged time. (I got it like that), however for many it worked by reducing the time step. Whatever the timestep you give in the solver, its just for post processing and it has nothing to do with the calculation (I hope so), as the comsol has inbuilt time stepping which will calculate at those time steps. I still puzzled at the error. post me a msg if u get rid of this error.
Badri Suhaini
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Posted: 9 years ago Dec 15, 2015, 6:10 p.m. EST
Hello

I solved the error already,
I did it by reducing the time step in my "Study: Time-dependent" for example by making range (0,0.5,1) to range (0,0.1,1).

And I also followed the "improving convergence in nonlinear time dependent model" on the COMSOL discussion. (www.comsol.com/support/knowledgebase/1127/)

Do you know what it means by convergence? What does it value shows actually from the image that I have attached? What does it mean if the convergence decreases or increases as time goes on?

Regards,
Badri
Hello I solved the error already, I did it by reducing the time step in my "Study: Time-dependent" for example by making range (0,0.5,1) to range (0,0.1,1). And I also followed the "improving convergence in nonlinear time dependent model" on the COMSOL discussion. (http://www.comsol.com/support/knowledgebase/1127/) Do you know what it means by convergence? What does it value shows actually from the image that I have attached? What does it mean if the convergence decreases or increases as time goes on? Regards, Badri
Krishnaswamy Veluswamy
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Posted: 9 years ago Dec 16, 2015, 4:30 a.m. EST
Hi,

There is already an discussion on convergence in the forum,

here you go for the link,

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

Hope it helps.
Hi, There is already an discussion on convergence in the forum, here you go for the link, http://www.comsol.com/community/forums/general/thread/35375/ Hope it helps.
Badri Suhaini
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Posted: 9 years ago Dec 17, 2015, 2:12 a.m. EST
Thanks
Thanks

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