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Hello everybody: please help me: (no convergence)

Posted Oct 19, 2010, 7:01 p.m. EDT 3 Replies

Mohammadreza Barzegaran
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I always get these two message in my simulation with comsol 3.5a

1st: Failed to find a solution:
Divergence of the linear iterations.
Returned solution has not converged

2nd:
Failed to find a solution:
The relative residual is greater than the relative tolerance, for the direct solver.
Returned solution has not converged.

my simulation is in quasi-static electromagnetic analysis and I used almost all of solvers: GMRES, FGMRES and any kinds of pre- and post-conditioners.


Is it because of solver or meshing?
3 Replies Last Post Oct 20, 2010, 6:11 p.m. EDT
Danial Tz
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Posted: 1 decade ago Oct 20, 2010, 2:07 a.m. EDT
I would suggest always to start with a simple model and simpler solvers than iterative solvers. Use Pardiso solver, or if your model is not too large use MUMPS solver, which is even more robust.

movaffagh bashi,
danial

--
Comsol 4.0a
Ubuntu 10.04.1
I would suggest always to start with a simple model and simpler solvers than iterative solvers. Use Pardiso solver, or if your model is not too large use MUMPS solver, which is even more robust. movaffagh bashi, danial -- Comsol 4.0a Ubuntu 10.04.1
Özen Özdemir
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Posted: 1 decade ago Oct 20, 2010, 3:48 a.m. EDT
Be sure that your boundary conditions are well defined and you have consistent units for material properties.

Regards,
Özen
Be sure that your boundary conditions are well defined and you have consistent units for material properties. Regards, Özen
Mohammadreza Barzegaran
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Posted: 1 decade ago Oct 20, 2010, 6:11 p.m. EDT
I checked everything again and I changed the B-H curve into consistent mur which has had effect and the solution goes up to 99% but error in this moment with:

with GMRES solver relative tolerance is 1.9e-5 with relative residual 4.9e-8 so it again says:

failed to find a solution
the relative error is greater than the relative tolerance, for the direct solver
returned solution has not converged


but some answers are logical e.g voltage distribution but not magnetic field density.

Do you think it is because of importing the shape from another software. is the relative tolerance of importing important?
I checked everything again and I changed the B-H curve into consistent mur which has had effect and the solution goes up to 99% but error in this moment with: with GMRES solver relative tolerance is 1.9e-5 with relative residual 4.9e-8 so it again says: failed to find a solution the relative error is greater than the relative tolerance, for the direct solver returned solution has not converged but some answers are logical e.g voltage distribution but not magnetic field density. Do you think it is because of importing the shape from another software. is the relative tolerance of importing important?

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