[Getdp] Convergence problem with inhomogeneous Helmholtz equation

Lars Rindorf lhr at com.dtu.dk
Fri Jan 4 14:08:15 CET 2008

Here you go. Thanks for the help.


-----Original Message-----
From: Colignon David [mailto:David.Colignon at ulg.ac.be]
Sent: Fri 1/4/2008 12:07 PM
To: Lars Rindorf
Cc: getdp at geuz.org
Subject: Re: [Getdp] Convergence problem with inhomogeneous Helmholtz      equation


can you also send us the  solver.par  file you use ?



> Dear all
> I am having some problems with the convergence of the solution of an inhomogeneous Helmholtz
> equation. The problems occurs for frequencies of the driving term which are about more than five
> times the fundamental eigenfrequency of the system. For the solver parameters I use the default
> with the maximum number of iterations increased to 3000. I have tried to change the solver and
> the dimension of the Krylov space. Changing the dimension of the Krylov seems to do something,
> although it does not solve the problem. The driving term of the inhomogeneous equations is applied
> in a point. I tried a line, and a subdomain and for those the problem was the same.
> I've made the model in Comsol, and here there was no problem. I also tried to change my nodal
> field to a 1P form, but this made no difference.
> Can anyone help?
> I have attached the files. The model offers two resolutions: 'static' and 'eig'. Choose 'static'.
> Also choose 'static' for the postoperation.
> Kind regards
> Lars Rindorf
> The Danish Institute of Technology
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