Dear Yuri,
There is of course no problem to transcribe your problem into the
assembly language of Getfem. You can mixt domain and boundary terms with
no problem.
Just a question on the expression you give : some polynomials are placed
outside the integrals. Is it normal and if yes, what is the sense of this.
Depending if you use the Matlab or Python or Scilab interface or if you
write directly your code in C++, you can find some examples helping you
to create the framework of your code in the test directories of Getfem
(see http://getfem.org/tutorial/index.html)
For instance, what you denote the "implicit boundary term" can be coded
by an assembly string of the following form
"([P5(X[1],X(2]), P6(X[1],X[2]).Grad_u + l*u)*Test_lambda - lambda*Test_u"
where 'u' and 'lambda' are the unknowns and P5, P6 functions should be
defined first (if you have an explicit expression, you can just plug it
here), and 'l' is a data that should be declared.
Regards,
Yves.
Le 10/10/2017 à 20:02, Юрий Кульчицкий a écrit :
Dear Getfem users,
I am experiencing an issue related to the problem formulation in the
case when there are both boundary integrals and usual integrals in the
2D case.
A boundary integral arises both from adding an implicit boundary
condition using an augmented Lagrange formulation and from the basic
weak form equation. It also implies an additional unknown (which is a
corresponding multiplier) and an additional test function.
May you point to me a way how can I formulate the problem correctly? I
would be very grateful for any help. I tried to understand how bricks
work, but so far with no success related to different integration domains.
I also enclose the full (simplified) weak form as png image if it
would help: https://image.ibb.co/jTwUDw/La_Te_X_Example.png.
Sorry if this question is too simple. I'm not quite familiar with the
library and the inner details of its FEM realization yet.
Regards,
Yuri Kulchitsky
--
Yves Renard ([email protected]) 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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