On Wednesday 04 June 2008 10:30, Sébastien Janas wrote: > Hi all, > > I want to solve the transient linear equation of diffusion. > > It seems that there is no function pre-build in getfem for the > transient problems. So I assemble the mass matrix (MM) and stiffness > matrix (SM) "manually", and then construct the linear system A*X=B > using the backward euler > > A = (MM + delta t * SM) > B = MM * X(t-1) > > Then I have to impose dirichlet conditions on the surface. I import my > mesh from gmsh, where the surface are tagged with a number (in my case > 200). How can I modify my linear system to take into accompt the > dirichlet conditions? All the functions I found in the documentation > are in the case where you use model bricks or standard assembly > procedures... > > If I can have the list of node numbers tagged by 200 I would use the > penalty method. But I am not able to obtain these list. > > I am using the python interface of getfem. > > Thanks for your help, > > Best regards, > > Janas Sébastien
This is true that there is no general strategy proposed for transient problems, especially with the matlab or python interfaces. This is however not easy to build such a general strategy since the situation can vary a lot for differente time integration schemes. However, You can have the list of nodes on a boundary with the command gf_mesh_fem_get(MF, 'dof on region', [bnum]); but you have first to tag the boundary with the command gf_mesh_set(M, 'region', int bnum, imat CVFLST); (see the Matlab examples). Yves. -- Yves Renard ([EMAIL PROTECTED]) tel : (33) 04.72.43.87.08 Pole de Mathematiques, INSA de Lyon fax : (33) 04.72.43.85.29 20, rue Albert Einstein 69621 Villeurbanne Cedex, FRANCE http://math.univ-lyon1.fr/~renard --------- _______________________________________________ Getfem-users mailing list [email protected] https://mail.gna.org/listinfo/getfem-users
