[Getdp] Magnetodynamic 3D - Electromagnetic circuit element

[Florin CIUPRINA]

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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