From: robert <robert.bodner@un...>  20101220 16:08:21

Hi, I am trying to build a model which solves the same equation as in ex9. I would like to specify the boundary conditions in a way that the flux out of the system on the left side equals the flux coming in on the right side. I am trying to use something like: for (unsigned int side=0; side<elem>n_sides(); side++) if (elem>neighbor(side) == NULL) { const std::vector<std::vector<Real> >& phi_face = fe_face>get_phi(); const std::vector<Real>& JxW_face = fe_face>get_JxW(); const std::vector<Point >& qface_point = fe_face>get_xyz(); fe_face>reinit(elem, side); for (unsigned int qp=0; qp<qface.n_points(); qp++) { const Real xf = qface_point[qp](0); const Real yf = qface_point[qp](1); const Real zf = qface_point[qp](2); const Real value = neumann_value(xf, yf, zf); for (unsigned int i=0; i<phi_face.size(); i++) Fe(i) += JxW_face[qp]*value*phi_face[i][qp]; } } but I am not sure how to determine neumann value for the outgoing flux on the other side. Thanks for your help, Robert 