Hello,
I came across this old thread, and successfully used the provided code in
my own code (https://github.com/l-korous/mhdeal) - thank you Andreas - and
I want to share how I used it:
- here are the (slightly changed) files provided by Andreas:
https://github.com/l-korous/mhdeal/blob/master/DealiiExtensions.h
https://github.com/l-korous/mhdeal/blob/master/DealiiExtensions.cpp
* I changed the custom class PeriodicBoundary's functionality into simple
arrays of boundary_ids and directions -
https://github.com/l-korous/mhdeal/blob/master/DealiiExtensions.h#L54
- here is the usage of collect_periodic_faces & add_periodicity:
https://github.com/l-korous/mhdeal/blob/master/parameters.cpp#L65
- and here is the usage of the custom functions from Andreas:
https://github.com/l-korous/mhdeal/blob/master/problem.cpp#L50
Many thanks
On Monday, February 1, 2016 at 3:36:20 PM UTC+1, Nectarios wrote:
>
> Dear Andreas,
>
> Thank you very much for your help. I will look at it and let you know how
> things go.
>
> Best Regards,
>
> Nectarios
>
> On Mon, Feb 1, 2016 at 11:08 AM, Andreas Krämer <[email protected]
> <javascript:>> wrote:
>
>> Hi Nectarios,
>>
>> the way I did it works as follows (starting with an unrefined grid):
>>
>> - Collect periodic faces to create a halo layer of ghost cells across
>> the periodic boundary:
>> // collect periodic faces and extend halo layer of ghost cells across
>> periodic boundaries
>> // take care: collect_periodic_faces must not be called for a
>> refined grid
>> if (m_triangulation->n_levels() > 1) {
>> throw PeriodicBoundaryNotPossible(
>> "The periodic boundaries have to be set before the
>> refinement.");
>> }
>> std::vector<
>> dealii::GridTools::PeriodicFacePair<
>> typename Mesh<dim>::cell_iterator> > matched_pairs
>> ;
>> dealii::GridTools::collect_periodic_faces(*m_triangulation,
>> m_boundaryIndicator1, m_boundaryIndicator2, m_direction,
>> matched_pairs);
>> // add halo layer
>> m_triangulation->add_periodicity(matched_pairs);
>>
>>
>>
>> - Refine grid (if you want to) and distribute DoFs
>> - Create a cell map that identifies faces at the two sides of a
>> periodic boundary
>> PeriodicCellMap<dim> m_cells;
>> DealIIExtensions::make_periodicity_map_dg(doFHandler,
>> m_boundaryIndicator1, m_boundaryIndicator2, m_direction, m_cells);
>>
>> - Make the sparsity pattern, incorporating the PeriodicCellMap (see
>> function make_sparser_flux_sparsity_pattern to get the idea). In general
>> you could just call deal.II's make_flux_sparsity_pattern and iterate over
>> the PeriodicCellMap to add the missing entries.
>> - Assemble the system, incorporating the PeriodicCellMap to identify
>> neighbors across periodic faces. I did something like
>> // loop over all cells
>> ...
>> // loop over all faces
>> for (size_t j = 0; j < dealii::GeometryInfo<dim>::faces_per_cell;
>> j++) {
>> //Faces at boundary
>> if (cell->face(j)->at_boundary()) {
>> size_t boundaryIndicator = cell->face(j)->boundary_id();
>> if (m_boundaries->isPeriodic(boundaryIndicator)) {
>> // Apply periodic boundaries
>> const boost::shared_ptr<PeriodicBoundary<dim> >&
>> periodicBoundary =
>> m_boundaries->getPeriodicBoundary(
>> boundaryIndicator);
>> assert(periodicBoundary->isFaceInBoundary(cell, j));
>> typename dealii::DoFHandler<dim>::cell_iterator
>> neighborCell;
>> size_t opposite_face =
>> periodicBoundary->
>> getOppositeCellAtPeriodicBoundary(
>> cell, neighborCell); // this function
>> extracts the neighbor cell from the PeriodicCellMap
>> // now assemble And Distribute Internal Face with the
>> periodic neighbor cell
>>
>>
>> The names of the functions should give you an idea what actually
>> happens here.
>>
>>
>> PeriodicCellMap, make_periodicity_map_dg and make_sparser_flux_sparsity
>> pattern are defined in the attached file to give you a rough idea (this
>> version works better than the one posted before).
>>
>> The code is part of a bigger framework, so you will have to change it
>> quite a bit before using it. However, the most important function,
>> make_periodicity_map_dg, should also work for your code.
>>
>>
>> If you have further questions, I'm happy to help.
>>
>> Best,
>>
>> Andreas
>>
>>
>>>
>>>> --
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>
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