Dear Hamed, The problem here is that VectorTools::interpolate_boundary_values always applied boundary values to surfaces in 3d, or lines in 2d. You cannot directly apply point constraints using this function. What is happening here is that you've set a component mask which says that for ALL of the specified components on a given surface, you wish to add some constraint. Next you define the constraint using a function. By default, the values returned by the function are zero (this is what Vector<double> &values is initialised as), and you then can change their value based on position. Note that it is the value that changes, not whether they are actively constrained or not. So, your function is effectively doing nothing tha the ZeroFunction wouldn't already do, since based on some position-dependent criterion you're changing the returned values from zero to zero!
However, if you're really wanting to implement point constraints then there is some reprise. Look at this post <https://groups.google.com/forum/#!searchin/dealii/vertex_dof_index%7Csort:date/dealii/gT3OJ3jfwKg/bwbhduSCBAAJ> and other posts <https://groups.google.com/forum/#!searchin/dealii/vertex_dof_index|sort:date> on how to use the vertex_dof_index, and then manually add constraint lines your constraint matrix. Regards, J-P On Friday, October 21, 2016 at 1:38:19 AM UTC+2, Hamed Babaei wrote: > > Hi friends, > > For an elastic problem, I am going to apply zero boundary displacements > for three specific points on the center of -x, -y and -z planes of a cubic > domain. > I have already done this but for the boundary surface not a boundary point > (the same as incremental_boundary_displacement in step-18). > The following is what I wrote to do so which doesn't work properly. In > fact, it fixes the whole -x, -y and -z surfaces, not just for the three > points on them that I intended. > > template <int dim> > class BoundaryCondition : public Function<dim> > { > public: > BoundaryCondition (const int boundary_id); > virtual void vector_value (const Point<dim> &p, > Vector<double> &values) const; > virtual void vector_value_list (const std::vector<Point<dim> > > &points, > std::vector<Vector<double> > > &value_list) const; > private: > const int boundary_id; > > }; > template <int dim> > BoundaryCondition<dim>::BoundaryCondition (const int boundery_id) > : > Function<dim> (dim), > boundary_id(boundary_id) > > {} > template <int dim> > inline > void > BoundaryCondition<dim>::vector_value (const Point<dim> &p, > Vector<double> &values) const > { > Assert (values.size() == dim, > ExcDimensionMismatch (values.size(), dim)); > > Point<dim> point_x; > point_x(1) = 5; > point_x(2) = 5; > > Point<dim> point_y; > point_y(0) = 5; > point_y(2) = 5; > > Point<dim> point_z; > point_z(0) = 5; > point_z(1) = 5; > > > if (boundary_id ==0 && ((p-point_x).norm_square() > <(0.5e-9)*(0.5e-9))) > values(0) = 0; > else if (boundary_id ==2 && ((p-point_y).norm_square() < > (0.5e-9)*(0.5e-9))) > values(1)= 0; > else if (boundary_id ==4 && ((p-point_z).norm_square() < > (0.5e-9)*(0.5e-9))) > values(2)= 0; > > } > template <int dim> > void > BoundaryCondition<dim>::vector_value_list (const > std::vector<Point<dim> > &points, > std::vector<Vector<double> > > &value_list) const > { > const unsigned int n_points = points.size(); > Assert (value_list.size() == n_points, > ExcDimensionMismatch (value_list.size(), n_points)); > for (unsigned int p=0; p<n_points; ++p) > BoundaryCondition<dim>::vector_value (points[p], > value_list[p]); > } > > .....and in the constraint I have > added VectorTools::interpolate_boundary_values for every boundary plane, > for example for the -x plane it looks like : > > > VectorTools::interpolate_boundary_values(dof_handler, > boundary_id, > > BoundaryCondition<dim> (boundary_id), > constraints, > > fe.component_mask(x_displacement)); > > > I don't know why it doesn't recognize the if condition " if > (boundary_id ==0 && ((p-point_x).norm_square() <(0.5e-9)*(0.5e-9)))" !!! > > I was wondering if you know where I am making mistake, or if there is any > step in which this boundary condition has applied. > > Thanks, > Hamed > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
