3D Crouzeix-Raviart (P1nc3d) in FreeFEM?

General Discussion
1

Dear all,

I hope this message finds you well.

I am currently working on a 3D numerical simulation that requires the use of the Crouzeix-Raviart finite element (non-conforming P1) on tetrahedral meshes. I am aware that FreeFEM natively supports P1nc for 2D problems, but I can’t find the 3D version.

Does a community plugin exist for this, or any known workaround? Thank you very much for your time and for sharing your expertise.

Best regards,

PegasusZhang

2

I sorry, this fini element is not in freefem in 3d,

I will add rapidly a plugin P1nc3d

3

Dear Professor Hecht,

Thank you very much for your prompt reply and for confirming this. That is wonderful news! I will keep an eye out for the P1nc3d plugin update.

I really appreciate you taking the time to address this, and thank you for your continuous work on FreeFEM.

Best regards,
PegasusZhang

4

I have make a new plugins, not realy tested,

The plugin

Element_P1nc_3d.cpp.zip (2.3 KB)

Unzippe and compile with

Host-004:seq hecht$ ff-c++ Element_P1nc_3d.cpp

clang++ -c -I../seq/include -Wno-undefined-var-template -m64 -fPIC -DNDEBUG -O3 -std=gnu++14 -DBAMG_LONG_LONG -DNCHECKPTR -fPIC -I/usr/local/ff+±4.16/ff-petsc/r/include/suitesparse -I/usr/local/ff+±4.16/ff-petsc/r/include -I/opt/homebrew/Cellar/hdf5/2.0.0_1/include -I/opt/homebrew/include ‘Element_P1nc_3d.cpp’

clang++ -bundle -undefined dynamic_lookup -Wno-undefined-var-template -m64 -fPIC -DNDEBUG -O3 -std=gnu++14 -DBAMG_LONG_LONG -DNCHECKPTR -fPIC -I/usr/local/ff+±4.16/ff-petsc/r/include/suitesparse -I/usr/local/ff+±4.16/ff-petsc/r/include -I/opt/homebrew/Cellar/hdf5/2.0.0_1/include -I/opt/homebrew/include ‘Element_P1nc_3d.o’ -o Element_P1nc_3d.dylib

clang++ -bundle -undefined dynamic_lookup -Wno-undefined-var-template -m64 -fPIC -DNDEBUG -O3 -std=gnu++14 -DBAMG_LONG_LONG -DNCHECKPTR -fPIC -I/usr/local/ff+±4.16/ff-petsc/r/include/suitesparse -I/usr/local/ff+±4.16/ff-petsc/r/include -I/opt/homebrew/Cellar/hdf5/2.0.0_1/include -I/opt/homebrew/include ‘Element_P1nc_3d.o’ -o ../mpi/Element_P1nc_3d.dylib -L/usr/local/ff+±4.16/ff-petsc/r/lib -lmpicxx -lmpi -lpmpi

the test :

testFE-P1nc3d.edp (551 Bytes)

I will had this , this week in develop branch.

5

I put this motif see add P1ncS and add too in CHANGELOG.md, and update plugin/seq/Makefil… · FreeFem/FreeFem-sources@08fbba3 · GitHub

and correct of P4 finite element in 3d

6

Dear Professor Hecht,

I tested the P1nc3d element in a 3D Stokes problem, and it performed perfectly. Thanks again for the rapid fix—it’s exactly what I needed!

Best,
PegasusZhang