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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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Slow and Constant Convergence.

Posted 16.03.2012, 15:47 GMT-4 Fluid & Heat, Computational Fluid Dynamics (CFD), Mesh, Results & Visualization, Studies & Solvers Version 4.2 4 Replies

Rui Silva
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Hi folks,

I am running a 3D COMSOL simulation and the problem is that the simulation is sort of stuck and the same
values and it does not change that much (see attached pic)...

Is there something I can do to accelerate the convergence.

I have tried using the Inconsistent Stabilization but it changes my values a lot in the final resultsa, so that's a no go!

Anyone has any alternatives?

I was reading the documentation and notice the numerical damping, but there is few information regarding this subject...

Any thoughts?

Best Regards,

Rui

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4 Replies Last Post 20.03.2012, 10:12 GMT-4
Rui Silva
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Posted: 1 decade ago 19.03.2012, 13:03 GMT-4
Could use some help on this subject...


And to provide some more details:

My model is highly non-linear, since it is a modified multiphase flow.

I have modified the equations in the "Equation node".

Perhaps one approach would be to choose a more suited solver for nonlinear PDE.

Does anyone have some experience with this subject?

Best Regards,


Rui Silva
Could use some help on this subject... And to provide some more details: My model is highly non-linear, since it is a modified multiphase flow. I have modified the equations in the "Equation node". Perhaps one approach would be to choose a more suited solver for nonlinear PDE. Does anyone have some experience with this subject? Best Regards, Rui Silva
Lechoslaw Krolikowski
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Posted: 1 decade ago 20.03.2012, 06:20 GMT-4
Hi,
See: 1127: "Improving convergence in nonlinear time dependent models" in the Support Knowledge Base.
Best Regards,
Andrzej
Hi, See: 1127: "Improving convergence in nonlinear time dependent models" in the Support Knowledge Base. Best Regards, Andrzej
Rui Silva
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Posted: 1 decade ago 20.03.2012, 08:17 GMT-4
Thank you for your reply Andrzej.

I am implementing a stationary solver.

Is it still applicable to Stationary Problems?

Best Regards,

Rui Silva
Thank you for your reply Andrzej. I am implementing a stationary solver. Is it still applicable to Stationary Problems? Best Regards, Rui Silva
Lechoslaw Krolikowski
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Posted: 1 decade ago 20.03.2012, 10:12 GMT-4


I am implementing a stationary solver.

Is it still applicable to Stationary Problems?



No.

Useful information about convergence can be found in the User's Guide. Ver. 4.2
Achieving Convergence When Solving Nonlinear Equations, page 439 (pdf file).
[QUOTE] I am implementing a stationary solver. Is it still applicable to Stationary Problems? [/QUOTE] No. Useful information about convergence can be found in the User's Guide. Ver. 4.2 Achieving Convergence When Solving Nonlinear Equations, page 439 (pdf file).

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