Re: [Getfem-users] Laplacian with Q_1 élément.

[Yves Renard]

Dear Yassine,

Yes, you are right. There is a superconvergence phenomenon in both cases.
I do not see what is the reason, the integration method is correct.
May be, the fact that the mesh is nearly structured. It would be interesting
to make the experiment in a fully non-structured case.

Best regards,

Yves.




Le 16/02/2016 11:05, Yassine ZAIM a écrit :

Dear Dr. Yves, 

Thank you so much for your answer and your time. 

I try with "MESH_NOISED = 1;"

For exemple :

for "NX = 127; Number of dof : 16384" : I found the error_H1 = 1.239379991943454e-05

for "NX = 255; Number of dof : 65536" : I found the error_H1 =3.083252284962158e-06

Order = Log2(1.239379991943454e-05/3.083252284962158e-06)=2.0071.

Maybe we will have the superconvergence phenomena in the both cases.

​Dear Thoma​s,

Thank you so much for your answer and your time. 

For me I work with C++, I don't use any interfaces, because I need to do some modifications later. The functions used for computation of error are getfem::asm_L2_norm and getfem::asm_H1_norm.

Best regards.

2016-02-16 9:36 GMT+00:00 Thomas Linse <address@hidden>:

How did you calculate the L2 and H1 norms? I found "correct" convergence for a similar 1D problem when calculating the norms "by hand" (using Gauss integration), whereas the norms calculated using "gf_compute" from the scilab interface showed a larger convergence rate.

Maybe "gf_compute" (which calls getfem::asm_L2_norm or dasm_H1_norm) does not use the necessary order of integration?

Kind regards,

Thomas

On 16.02.2016 09:59, Yves Renard wrote:

Dear Yassine,

Superconvergence phenomena are quite common when a structured mesh is used. If you use the option "MESH_NOISED", this should (unfortunately !) disapear.

Best Regards,

Yves.


Le 15/02/2016 15:01, Yassine ZAIM a écrit :

Hi,

I want to ask you if someone has already solved the laplacian problem that exists in the tests directory with the Q_1 element in 2 dimension. Because I find the order of convergence equal to "2" for the L2 and H1 norme. what is not normal.

Best regards.

Bonjour,

S.v.p j'aimerais savoir si quelqu'un de vous a déjà testé le problème de laplacian qui exist dans la répertoire des tests avec l'élément Q_1 en dimension 2. J'ai testé ça et je trouve le même ordre pour les deux norme L2 et H1 (Ordre(L2) = Ordre(H1) = 2). Ce qui contredit la théorie.

Merci d'avance pour vos réponse.

Cordialement.

--

ZAIM Yassine 

PhD Student in Applied Mathematics

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  Yves Renard (address@hidden)       tel : (33) 04.72.43.87.08
  Pole de Mathematiques, INSA-Lyon             fax : (33) 04.72.43.85.29
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  http://math.univ-lyon1.fr/~renard

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Getfem-users mailing list
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_______________________________________________
Getfem-users mailing list
address@hidden
https://mail.gna.org/listinfo/getfem-users

--

ZAIM Yassine 

PhD Student in Applied Mathematics

-- 

  Yves Renard (address@hidden)       tel : (33) 04.72.43.87.08
  Pole de Mathematiques, INSA-Lyon             fax : (33) 04.72.43.85.29
  20, rue Albert Einstein
  69621 Villeurbanne Cedex, FRANCE
  http://math.univ-lyon1.fr/~renard

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