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Error: Failed to find a solution. Divergence of the linear iterations. Returned solution is not converged.

Posted Nov 28, 2011, 4:36 p.m. EST Version 4.2a 3 Replies

Hasan Faraby
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Hello All,

I am trying to simulate the inductance of a 10 turn solenoid.
The geometry was drawn using extrudes and revolves in COMSOL 4.2(didn't use the Helix primitive).
I used free tetrahedral mesh for the geometry.
The mesh doesn't show any error.
But when I try to solve the model I get the following message :

Failed to find a solution.
Divergence of the linear iterations.
Returned solution is not converged.


Any help regarding this will be highly appreciated.
Interestingly, when I reduce the radius of the solenoid to half, it solves without any error.


Regards
Hasan
3 Replies Last Post Feb 10, 2015, 10:06 a.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Nov 29, 2011, 1:34 a.m. EST
Hi

have you checked that your mesh size is compatible with the expected gradients and frequencies (that you resolve gradient variations well enough). Mostly 3D ACDC models become so heavy that you need supercomputers, so it's worth a little estimation if a 3D approach is feasible, if not then try a 2D-axi, most coils are correctly represented in 2D-axi, and the model is far lighter (RAM wise) but you need to write some equations. Check the model library there are several examples (and you have advanced BC conditions for coils, check your doc)

--
Good luck
Ivar
Hi have you checked that your mesh size is compatible with the expected gradients and frequencies (that you resolve gradient variations well enough). Mostly 3D ACDC models become so heavy that you need supercomputers, so it's worth a little estimation if a 3D approach is feasible, if not then try a 2D-axi, most coils are correctly represented in 2D-axi, and the model is far lighter (RAM wise) but you need to write some equations. Check the model library there are several examples (and you have advanced BC conditions for coils, check your doc) -- Good luck Ivar
Haitao Yang
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Posted: 1 decade ago Feb 8, 2012, 5:29 p.m. EST
Hi Ivar

I have a similar problem. I am trying to simulation the vibration of cantilever in fluid. and I add a boundary load on one boundary of the load in order to excite it to vibrate. But only when the time step is big, it can converge. When the time step becomes small enough for my question, there is always one error " recoverable error in residual, but the solver can not recover it.

The attached is the model, Can you have a look and give some suggestions ?
Thank you very much.

Best Regards
Haitao
Hi Ivar I have a similar problem. I am trying to simulation the vibration of cantilever in fluid. and I add a boundary load on one boundary of the load in order to excite it to vibrate. But only when the time step is big, it can converge. When the time step becomes small enough for my question, there is always one error " recoverable error in residual, but the solver can not recover it. The attached is the model, Can you have a look and give some suggestions ? Thank you very much. Best Regards Haitao

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Abdulrazak Otaru
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Posted: 10 years ago Feb 10, 2015, 10:06 a.m. EST
Hi ....I am student of University of Nottingham, UK
I have been trying to solve Stokes equation in 3D micro - geometrical meshed. I'm currently exploring the Fluid model>Creeping flow>stationary of COMSOL 4.4. Comsol failed to solve my problem. it continue showing me "Failed to find a solution. Divergence of the linear iterations.Returned solution is not converged". Going through discussion forum, someone suggested that unchecking "p" on "solver manager" in "solver paramters" would help solve the problem. Please can anyone help me on how to locate this SOLVER MANAGER in COMSOL 4.4.? or what is the best approach?..

Thank you all,

Otaru, A.J.
Hi ....I am student of University of Nottingham, UK I have been trying to solve Stokes equation in 3D micro - geometrical meshed. I'm currently exploring the Fluid model>Creeping flow>stationary of COMSOL 4.4. Comsol failed to solve my problem. it continue showing me "Failed to find a solution. Divergence of the linear iterations.Returned solution is not converged". Going through discussion forum, someone suggested that unchecking "p" on "solver manager" in "solver paramters" would help solve the problem. Please can anyone help me on how to locate this SOLVER MANAGER in COMSOL 4.4.? or what is the best approach?.. Thank you all, Otaru, A.J.

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