Thanks Jean-Paul for creating the simple example. I ran the code and
indeed see that it does say zero constraints for the chosen example,
although I too do not know much about the hanging support points in
p-refinement.
Best,
Deepak
On 25-08-16 10:34, Jean-Paul Pelteret wrote:
Hi Deepak,
Ok, so I've created a minimal working example to demonstrate what
you're seeing here. I'm not sufficiently familiar with the
p-refinement part of the hp functionality/implementation to tell
whether this is truly the expected behaviour or not. I see that the
examples and description
<https://www.dealii.org/8.4.1/doxygen/deal.II/group__constraints.html#ga3eaa31a679484e80c193e74e8a967dc8>
in the documentation mix h- and p-refinement, so are _perhaps_ not
sufficiently clear to describe the expected outcome of this
configuration. Or maybe its a bug arising from the adjacent cells
being on the same refinement level (i.e. there are no actual hanging
_nodes_). Perhaps someone else could clarify this?
J-P
On Tuesday, August 23, 2016 at 9:45:41 AM UTC+2, Deepak Gupta wrote:
Dear Daniel and others,
Below is the part of my code that might explain better:
*//Below is the constructor for FEM class (a part of my own
library). The part of the code below in BOLD states that I assign
different order shape functions alternatively.*
template<int dim>
FEM<dim>::FEM(
Triangulation<dim> &obj_triangulation,
hp::DoFHandler<dim> &dof_handler,
DefineMesh<dim> &obj_mesh){
this->mesh = &obj_mesh;
this->dof_handler = &dof_handler; // for the state field on
the analysis
this->triangulation = &obj_triangulation; //for the state
field on the analysis
//For Lagrange element
if (mesh->elementType == "FE_Q"){
for (unsigned int degree = 1; degree <=
mesh->max_el_order; ++degree){
fe_collection.push_back(FESystem<dim>(FE_Q<dim>(degree), dim));
}
}
//Quadrature collection for FE
for (unsigned int qrule = 1; qrule <= mesh->max_el_order + 11;
++qrule){
quadrature_collection.push_back(QGauss<dim>(qrule));
}
**//initializing the type of element for each cell of analysis mesh*
for (typename hp::DoFHandler<dim>::active_cell_iterator cell =
dof_handler.begin_active();
cell != dof_handler.end(); ++cell){
cell->set_active_fe_index(p_index);
++cell;
cell->set_active_fe_index(p_index+2);
}*
}
*//The setup() function is as follows, The line that prints the
no. of constraints is put in BOLD in the code
*template <int dim>
void FEM<dim>::setup_system(){
//FE mesh
dof_handler->distribute_dofs(fe_collection);
solution.reinit(dof_handler->n_dofs());
system_rhs.reinit(dof_handler->n_dofs());
analysis_density_handler->distribute_dofs(fe_analysis_density_collection);
//Used to add density on every node
hanging_node_constraints.clear();
DoFTools::make_hanging_node_constraints(*dof_handler,
hanging_node_constraints);
hanging_node_constraints.close();
*std::cout<<"No. of hanging node constraints :
"<<hanging_node_constraints.n_constraints()<<std::endl;*
DynamicSparsityPattern dsp (dof_handler->n_dofs());
DoFTools::make_sparsity_pattern (*dof_handler,
dsp,
hanging_node_constraints,
true);
sparsity_pattern.copy_from(dsp);
system_matrix.reinit(sparsity_pattern);
}*
*
*OUTPUT:
*No. of hanging node constraints : 0*
---------------------------------------------------------------------
*Could someone let me know why the no. of constraints is zero.
Since the p-order of neighboring elements differ, I would expect
constraints here.
Best regards
Deepak
On Fri, Aug 19, 2016 at 10:51 AM, Daniel Arndt
<d.ar...@math.uni-goettingen.de
<mailto:d.ar...@math.uni-goettingen.de>> wrote:
Deepak,
I am aware of the fact that
ConstraintMatrix.n_constraints() gives the number of
hanging nodes for h-refinement, but if I only use
p-refinement, can it give the number of hanging support
points occurring due to the difference in the order of
bases between two adjacent elements? I am expecting this
based on the description of the hp-refinement document.
I have been trying this but always get 0 hanging support
points, although I know that the some elements of the mesh
use Q1, others Q2.
That sounds definitely strange. step-27 uses a hp::DoFHandler
and make_hanging_node_constraints. Do you see that constraints
are created there?
If you can't find a solution looking at that example program,
can you reduce your code to a minimal example showing that no
constraints are created for p-refinement?
Best,
Daniel
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Deepak K. Gupta
PhD Candidate/Researcher
Structural Optimization & Mechanics
TU Delft / Precision & Microsystems Engineering
Faculty of Mechanical, Maritime & Materials Engineering (3mE)
Mekelweg 2, 2628 CD Delft, The Netherlands
T +31 (0)15 27 86818
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Room 3mE.G.1.150
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