Dear Yves,
That's great! It's indeed working now. Thank you very much for your help.
Best regards,
Phuoc
On 15/06/2018 16:38, Yves Renard wrote:
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
