Dear professor,
I tried with getfem 4.3.2 but the result is always the same.
I am sorry, I am trying to obtain a reduced version of the code but I obtain a
very strange behaviour of the Gradient of vel_0. I really cannot understand
why. Maybe I am introducing other errors... As soon as I am able to obtain a
short code I'll send you.
Anyway, if I assemble the term in that
way://----------------------------------------------------------------------------------------------------------------------------------------------
bgeot::base_vector result;
bgeot::base_vector result2;
getfem::ga_interpolation_Lagrange_fem(model_2,"Grad_vel_0_up.[0.0;1.0]",
p.mf_mult,result);
getfem::ga_interpolation_Lagrange_fem(model_2,"Grad_vel_0_dwn.[0.0;1.0]",
p.mf_mult,result2);
model_2.add_initialized_fem_data("G_vel_0_up", p.mf_mult, result);
model_2.add_initialized_fem_data("G_vel_0_dwn",p.mf_mult, result2);
getfem::add_linear_generic_assembly_brick(model_2,
p.mim_fil,"Print(Interpolate(G_vel_0_up,
my_transformation))*r.Interpolate(Test_lambda_up, my_transformation)");
getfem::add_linear_generic_assembly_brick(model_2,
p.mim_fil,"Print(Interpolate(G_vel_0_dwn,
my_transformation))*r.Interpolate(Test_lambda_dwn, my_transformation)");
//-----------------------------------------------------------------------------------------------------------------------------------------------------------------
it seems to work. The problem is that I do not know if P1 is correct for
Grad_vel_0, when vel_0 is P2.I still have to make more verifications to be
really sure.
Thank you,
Eleonora
Il Lunedì 16 Febbraio 2015 8:02, Yves Renard <[email protected]> ha
scritto:
Dear Eleonora,
And of course if you can isolate a piece of code with a clear problem, it can
help.
Yves.
Le 14/02/2015 20:01, Eleonora Piersanti a écrit :
Thank you for the answer.
I am using getfem 4.3.1.
Now, I found an alternative way to assemble the term that seems to work.
Anyway, I can try with the 4.3.2 version of the library.
Kind regards,
Eleonora
Il Sabato 14 Febbraio 2015 16:04, Yves Renard <[email protected]>
ha scritto:
Dear Eleonora,
I don't see any problem in your formulation. This should a priori work.
Do you use Getfem 4.3 ?
If yes, can you try either the svn version or the link below
http://math.univ-lyon1.fr/homes-www/renard/temp/getfem-4.3.2.tar.gz
and tell me if it fixes the problem (some bug fix of this type have been done
since 4.3 release).
Best regards,
Yves.
----- Original Message -----
From: "Eleonora Piersanti" <[email protected]>
To: [email protected]
Sent: Thursday, February 12, 2015 9:09:11 AM
Subject: [Getfem-users] Gradient of a velocity field using high level generic
assembly, partial mesh fem and Interpolate transformation
Dear professor, dear all,
I have to assemble a complicated term and I used the high level generic
assembly. The problem is the following.
I have a 2D mesh on which two fems are defined: mf_u that is P2 with qdim=2,
for velocity, and mf_mult with qdim=2, for Lagrange multiplier, that is P1.
This mesh is symmetric with respect to the x axis (y = 0). On the symmetry axis
there is a filament represented by a 1D segment that for the 2D mesh is a
boundary. On this segment an other mesh mesh made by 1D elements is defined and
a fem mf_fil based on Hermite elements is defined.
Now, for some reasons, I had to use the partial mesh fem object. I define
mf_u_up on the upper part of the 2D mesh and on the dof on the symmetry axis
(therefore on the filament too), and mf_u_dwn on the lower part of the 2D mesh
and on the dof on the symmetry axis (therefore on the filament too). In the
same way I define mf_mult_up and mf_mult_dwn.
Then, I declare a model, varables and data:
//-----------------------------------------------------------------------------------------------------------------------------------------------
getfem::model model_2;
model_2.clear();
model_2.add_initialized_fem_data("vel_0_up", mf_u_up, vel_0_up);
model_2.add_initialized_fem_data("vel_0_dwn",mf_u_dwn, vel_0_dwn);
model_2.add_fem_variable("lambda_up", mf_mult_up);
model_2.add_fem_variable("lambda_dwn", mf_mult_dwn);
model_2.add_fem_variable("r", p.mf_fil); //r is the displacement y
//Define the interpolate transformation from 2D mesh to 1D mesh
add_interpolate_transformation_from_expression(model_2, "my_transformation",
p.mesh_fil, p.mesh, "Print(X)");
getfem::add_linear_generic_assembly_brick(model_2,
p.mim_fil,"Print(Interpolate(Grad_vel_0_up, my_transformation).[0.0;
1.0])*r.Interpolate(Test_lambda_up, my_transformation)");
getfem::add_linear_generic_assembly_brick(model_2,
p.mim_fil,"Print(Interpolate(Grad_vel_0_dwn, my_transformation).[0.0;
1.0])*r.Interpolate(Test_lambda_dwn, my_transformation)");
model_2.assembly(getfem::model::BUILD_ALL);
//------------------------------------------------------------------------------------------------------------------------------------------------------------//
I need to compute an integral on the filament that is 1D with some quantities
that are 2D, therefore I use the Interpolate transformation.
vel_0_up, and vel_0_dwn are data that are previously computed and I also
exported them in .vtk so that I can obtain the terms Grad_vel_0_up.[0.0;1.0],
Grad_vel_0_dwn.[0.0;1.0] on the filament with paraview. As you can see, I used
the Print command so I could save the value of those quantities. Unfortunately,
they do not seem to be correct. In particular, the first component of
Grad_vel_0_up.[0.0;1.0] is the double than the one obtained with paraview while
for Grad_vel_0_dwn.[0.0;1.0] on the filament I obtain something that is almost
zero everywhere on the filament. I would expect something symmetric (maybe with
differnt sign) due to the fact that vel_0_up and vel_0_dwn are symmetric.
Am I doing something wrong? Is it possible that it is due to the fact that I
am using partial mesh fem?
I hope the question is clear.
Kind regards,
Eleonora.
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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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