HI all,
I'm trying to implement a time-dependent convection equation using DG
elements with periodic boundary conditions on and adaptive mesh.
However, when I try to adapt the mesh using periodic using this code:
// estimate the error in each cell
Vector<float> estimatedErrorPerCell(triangulation.n_active_cells());
//KellyErrorEstimator<dim>::estimate(dofHandler,
QGauss<dim-1>(feSystem.degree + 1), {}, solution.block(0),
estimatedErrorPerCell);
KellyErrorEstimator<dim>::estimate(dofHandler,
QGauss<dim-1>(feSystem.degree + 1), {}, solution, estimatedErrorPerCell);
// refine cells with the largest estimated error (80 per cent of the
error) and coarsens those cells with the smallest error (10 per cent of the
error)
GridRefinement::refine_and_coarsen_fixed_fraction(triangulation,
estimatedErrorPerCell, 0.8, 0.1);
// to prevent the decrease in time step size limit the maximal refinement
depth of the meshlimit the maximal refinement depth of the mesh
if( triangulation.n_levels()>maxGridLevel ) {
for( auto& cell :
triangulation.active_cell_iterators_on_level(maxGridLevel) ) {
cell->clear_refine_flag(); }
}
// store previous and current solution on the coarser mesh
std::vector<BlockVector<double> > tempSolution(2);
tempSolution[0] = oldSolution; tempSolution[1] = solution;
// transfer the solution vectors from the old mesh to the new one
SolutionTransfer<dim, BlockVector<double> > transfer(dofHandler);
// prepare for the refinement---we have to prepare the transfer as well
*triangulation.prepare_**coarsening_and_refinement();* // for some
reason, this doesn't tell the cells across a periodic boundary that they
need to be refined
transfer.prepare_for_coarsening_and_refinement(tempSolution);
// do the refinement and reset the DoFs
triangulation.execute_coarsening_and_refinement();
SetupSystem();
std::vector<BlockVector<double> > temp(2);
ReinitializeVector(temp[0]); ReinitializeVector(temp[1]);
transfer.interpolate(tempSolution, temp);
oldSolution = temp[0]; solution = temp[1];
constraints.distribute(oldSolution);
constraints.distribute(solution);
*I get this error:*
--------------------------------------------------------
An error occurred in line <992> of file
</home/add8536/Software/dealii/source/grid/tria.cc> in function
void dealii::{anonymous}::update_periodic_face_map_recursively(const
typename dealii::Triangulation<dim, spacedim>::cell_iterator&, const
typename dealii::Triangulation<dim, spacedim>::cell_iterator&, unsigned
int, unsigned int, const std::bitset<3>&, std::map<std::pair<typename
dealii::Triangulation<dim, spacedim>::cell_iterator, unsigned int>,
std::pair<std::pair<typename dealii::Triangulation<dim,
spacedim>::cell_iterator, unsigned int>, std::bitset<3> > >&) [with int dim
= 2; int spacedim = 2; typename dealii::Triangulation<dim,
spacedim>::cell_iterator = dealii::TriaIterator<dealii::CellAccessor<2, 2>
>]
The violated condition was:
dim == 1 || std::abs(cell_1->level() - cell_2->level()) < 2
Additional information:
This exception -- which is used in many places in the library --
usually indicates that some condition which the author of the code thought
must be satisfied at a certain point in an algorithm, is not fulfilled. An
example would be that the first part of an algorithm sorts elements of an
array in ascending order, and a second part of the algorithm later
encounters an element that is not larger than the previous one.
There is usually not very much you can do if you encounter such an
exception since it indicates an error in deal.II, not in your own program.
Try to come up with the smallest possible program that still demonstrates
the error and contact the deal.II mailing lists with it to obtain help.
For some reason the refinement does not seem to know that the boundaries
are periodic and that it should refine the cells on the other side of the
domain. I tried changing the refinement step so that instead of just
calling triangulation.prepare_coarsening_and_refinement();, I created my
own function that mimics the distributed triangulation (calling the
distributed version of enforce_mesh_balance_over_periodic_boundaries) that
does the following:
while( true ) {
triangulation.prepare_coarsening_and_refinement();
triangulation.update_periodic_face_map();
bool changed =
enforce_mesh_balance_over_periodic_boundaries(triangulation);
if( !changed ) { break; }
}
This fixed the error but I'm getting the strange behavior---it looks like
the cell face fluxes are no longer being computed correctly
Does anyone have any idea about what the issue could be? I know I left out
a lot of code, but hopefully I included the important bits.
Thanks,
Andy
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