Dear Phuoc,
The problem is indeed the same, to compute the location of gauss points
on a neighbour element, the inversion of the geometric transformation is
called. This inversion used a Newton algorithm whose starting point is a
node of the element ... (function find_initial_guess in
bgeot_geotrans_inv.cc).
I changed a bit the starting point, so it should work now. But this is
clear that the fact that the transformation is singular at the pyramid
tip is a difficulty.
Best regards,
Yves
Le 15/06/2018 à 11:53, Huu Phuoc BUI a écrit :
Dear Yves,
Thank you very much for your help.
Now it worked when computing the outer faces. But I faced another
problem of this mixed mesh. In fact, I'd like to compute the stress
jump at the inner faces using generic assembly, and GetFEM++ showed an
error like this:
"
File "/usr/local/lib/python2.7/dist-packages/getfem/getfem.py", line
5591, in asm_generic
return getfem('asm', 'generic', mim, order, expression, region,
model, *args)
RuntimeError: (Getfem::InterfaceError) -- Error in
getfem_generic_assembly_compile_and_exec.cc, line 3887 virtual int
getfem::ga_instruction_neighbour_transformation_call::exec():
Geometric transformation inversion has failed in neighbour transformation
"
So, as you said, this error comes from geometric transformation of
pyramid elements. Do you have an idea how to fix it?
Best regards,
Phuoc
On 15/06/2018 11:10, Yves Renard wrote:
Dear Phuoc,
The problem come from the fact that the test is made on the mean unit
normal vector on a face. This mean unit normal vector is computed by
averaging the unit normal vector on each geometrical node of a face.
Unfortunately, for a pyramid element, the transformation is singular
on the geometrical nodes.
I replaced the mean of normal vector by the normal vector on the mean
of geometrical nodes of the face. It fixes the problem. (I push the
change on the master branch).
Best regards,
Yves
Le 14/06/2018 à 15:40, Huu Phuoc BUI a écrit :
Dear Yves,
Please find the mesh attached.
Thank you for your help.
Best regards,
Phuoc
On 14/06/2018 14:52, Yves Renard wrote:
Dear Phuoc,
No, I see no reason. If you can just send me the mesh in a format
readable by GetFEM, I could check what is wrong.
Best regards,
Yves
Le 14/06/2018 à 10:24, Huu Phuoc BUI a écrit :
Dear Getfem-users,
I have a problem with computing the outer faces when using a mixed
mesh (having tetras, hexa, prisms and pyramids).
The error is:
face_left = m.outer_faces_with_direction([0, 0., -1.0], 0.01)
File "/usr/local/lib/python2.7/dist-packages/getfem/getfem.py",
line 1372, in outer_faces_with_direction
return self.get("outer_faces_with_direction", v, angle, CVIDs)
File "/usr/local/lib/python2.7/dist-packages/getfem/getfem.py",
line 1152, in get
return getfem('mesh_get',self.id, *args)
RuntimeError: (Getfem::InterfaceError) -- Error in
bgeot_geometric_trans.cc, line 381 const base_matrix&
bgeot::geotrans_interpolation_context::B() const:
Non invertible matrix
Please let me know if you have any idea. Thank you.
Best regards,
Phuoc
--
Yves Renard ([email protected]) tel : (33) 04.72.43.87.08
Pole de Mathematiques, INSA-Lyon fax : (33) 04.72.43.85.29
20, rue Albert Einstein
69621 Villeurbanne Cedex, FRANCE
http://math.univ-lyon1.fr/~renard
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