[petsc-users] Advice on identifying boundary vertices

[Aldo Bonfiglioli]

Dear all,

I am trying to identify the boundary vertices that belong to a given 
stratum of the Face sets. This is going to be used to prescribe 
Dirichlet-type bcs.

I can select the boundary faces (edges in 2D) of a given stratum using 
PetscCall(DMLabelGetStratumIS(label, stratum, user%bndryfaces(i), ierr)) 
and that looks ok;

I then try to identify the boundary vertices by looping over the points 
(edges in 2D/faces in 3D) of the face set of a given stratum and 
retrieve the vertices that make up each individual edge/face.

For reasons I fail to understand, the above procedure fails to identify 
certain vertices (those circled in the enclosed pdf where different 
colours mark different ranks) in a parallel environment.

Questions:

1. is there an available function that does what I am trying to do? I 
know that the boundary points can be found in the "marker" label, but I 
need to discriminate among Face Sets of different strata.

2. what might be wrong in the aforementioned approach?

Thanks,

Aldo

-- 
Dr. Aldo Bonfiglioli
Associate professor of Fluid Machines
Scuola di Ingegneria
Universita' della Basilicata
V.le dell'Ateneo lucano, 10 85100 Potenza ITALY
tel:+39.0971.205203 fax:+39.0971.205215
web: https://urldefense.us/v3/__http://docenti.unibas.it/site/home/docente.html?m=002423__;!!G_uCfscf7eWS!YLL7mzBlK9H_sEdtXob1AVklf8cVLhT3NTDdExIZsdI3xMfNHBoLXr92BmYzCXOuJqtm2L6OU4DJKV_81AkjvQf-Kra-Ym8P0tU$ 
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