Dear Radames, Neumann conditions are taken into account by the source term brick. In weak formulation, a Neumann condition is a source term on the corresponding boundary. See examples and http://download.gna.org/getfem/html/homepage/userdoc/model_source_term.html
Yves. On mardi 22 novembre 2011, [email protected] wrote: > Dear all, > > I'm a newbie to getfem++. > > I want to solve an isotropic homogenous elastostatic problem. The (first) > mesh is ready but I cannot see how to include my boundary conditions. > > Here are the equations of my problem: > > e_ij = (u_i,j + u_j,i)/2 in V > sigma_ij =lambda delta_ij epsilon_kk + 2 mu epsilon_ij in V with lambda, mu > Lamé coefficient sigma_ij,j + b_j = 0 in V with b data > u_i = w_i on S_D with w data > sigma_ij n_j = p1 n_i on S_N1 with p1 data and n the unit normal of the > surface (face) sigma_ij n_j = p2 n_i on S_N2 with p2 data and n the unit > normal of the surface (face) > > p1 and p2 are gas pressures. Therfore there is no tangential traction at > the surfaces S_Ni, but only normal pressure. S_N1 + S_N2 + S_D = \partial > V. > > > For the first three equations I can use the linear elasticity brick [1] > AFAICS. For the Dirichlet condition I can use the Dirichlet brick [2]. But > with the two Neumann boundaries I cannot see how to specify them. The > unknown of the FEM is the displacement field u. The boundary condition is > given in terms of sigma but not (directly) in terms of u. I expect that > the Neumann brick [3] implements u_i,j n_j = v_i, but that's not what I > need. How can I proceed? > At the moment I use the python interface, but I can move to the c++ > interface if it can solve my problem easier. > > [1] > [2] > [3] > > > Many thanks for any hints. > > Kind regards, > Radames > > > > > --- > E-Mail ist da wo du bist! Jetzt mit freenetMail ganz bequem auch unterwegs > E-Mails verschicken. Am besten gleich informieren unter > http://mail.freenet.de/mobile-email/index.html > > _______________________________________________ > Getfem-users mailing list > [email protected] > https://mail.gna.org/listinfo/getfem-users -- 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 --------- _______________________________________________ Getfem-users mailing list [email protected] https://mail.gna.org/listinfo/getfem-users
