[Getdp] Magnetodynamic 3D - Electromagnetic circuit element
Florin CIUPRINA
florin at elmat.pub.ro
Wed Apr 16 15:53:42 CEST 2003
Hello Christophe,
>Did you try to solve the linear system with a direct solver
>(Algorithm=11 in solver.par)?
Thank you very much for this advice. It finaly led me to some results.
Here you can see what I have done:
1) first trial:
Algorithm=11 and sparse matrix, and
I received the message:
GetDP : Error : Unknown algorithm for sparse matrix solver
2) second trial
Algorithm=11 and full matrix and this time I obtained
the solution which seems to be OK, for coarse mesh and low frequency.
However, for a dense mesh, there are problems with the memory (obviously
due to the full storage), and I cannot solve the problem at all.
3) other trials with iterative algorithms
For a relatively dense mesh (which I cannot solve with LU due to memory
limitation),
I have tried all the other available iterative algoritms. The only
one that converged was algorithm=10, but the convergence was extremely slow.
I improved its convergence by using scaling=4.
Matrix_Format 1
Matrix_Printing 0
Matrix_Storage 0
Scaling 4
Renumbering_Technique 1
Preconditioner 2
Preconditioner_Position 2
Nb_Fill 20
Permutation_Tolerance 0.05
Dropping_Tolerance 0
Diagonal_Compensation 0
Re_Use_ILU 0
Algorithm 10
Krylov_Size 40
IC_Acceleration 1
Re_Use_LU 0
Iterative_Improvement 0
Nb_Iter_Max 5000
Stopping_Test 1e-10
In this case, for 100Hz it takes 154 iterations, but, if I want to increase
the frequency (e.g. 10 KHz) it takes 817 iterations.
So, I wonder if:
- Can I use a direct solver for sparse matrices?
- Is there any possibility to improve the convergence of the iterative
method that
worked for this problem (algorithm=10) so that I would be able to work with
high
frequencies (up to GHz maybe...)?
I also noticed that, when using several frequencies in the same resolution, the
number of iterations is greater than the maximum number of iterations of the
independent resolutions for each frequency. I assume that this is due to
different
initializations. So, what do you reccommend? Is it better (faster) to solve
for
each frequency separately?
Thanks a lot for your helpful support.
With kind regards,
Florin
Florin Ciuprina, Ph.D.
Associate Professor
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POLITEHNICA University of Bucharest
Electrical Engineering Faculty
Electrical Materials Laboratory
Spl.Independentei 313, 77206, Bucharest, Romania
Tel: +40.21.402 92 91
Fax: +40.21.410 43 55
e-mail: florin at elmat.pub.ro
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