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. _______________________________________________ Getfem-users mailing list [email protected] https://mail.gna.org/listinfo/getfem-users _______________________________________________ Getfem-users mailing list [email protected] https://mail.gna.org/listinfo/getfem-users
