Automatic refinement with minimal level of refinement

[Lucas Campos]

Dear all,

I am creating a mesh using GridGenerator::hyper_shell. In this mesh, I want to divide the mesh into 

two distinct subdomains, radially. In order to do that, I need to refine the mesh at least once. Each 

of these cells carries an internal state that depends on its kind.

The issue I have is that, while improbable, in theory it is possible for 

GridRefinement::refine_and_coarsen_fixed_number to merge these cells back, which 

would be a mistake. Is there a way either configure the triangulation to consider the once refined 

state the coarsest possible?

The other solution I see is to "manually" input the once-refined mesh and then use 

create_triangulation, but that sounds cumbersome and error-prone.

Bests,
Lucas Campos

[luca.heltai]

After you have created your coarse mesh, you could GridTools::flatten_triangulation it. This will create a brand new coarse triangulation, containing only all your active cells.

L.

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[Lucas Campos]

Perfect! Thank you!

[Wolfgang Bangerth]

On 02/19/2018 05:37 AM, luca.heltai wrote:
> After you have created your coarse mesh, you could GridTools::flatten_triangulation it. This will create a brand new coarse triangulation, containing only all your active cells.

Alternatively, between the call to GridRefinement::refine_...() and
Triangulation::execute_coarsening_and_refinement(), you can go over all cells
and call
if (cell->level() == 1
&&
cell->coarsen_flag_set())
cell->clear_coarsen_flag()

This makes sure that once refined cells will never be coarsened again.

Best
W.

--
------------------------------------------------------------------------
Wolfgang Bangerth email: bang...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/