Thank you, Kostas. You are very dedicated!
It is OK, there are few ways to go. People I think have just got
used to the elegant and convenient way of integration in *getfem
*and are becoming lazy to do some work :)
Assuming that we have basic_dof_from_cvid and
basic_dof_nodes method we have everything we need to implement
Newton Cotes(for example) formulas manually for each edge.
It just takes some extra code and time
I prefer this way, maybe i will try the projection/ interpolation
approach soon.
But just for your and Yves notes, even in mechanics(especially in
fluids), evaluation of field circulation might be useful. Again
it is not a problem or issue just extra sci/tech/eng service
Regards and thank you for clarifying things, Egor
вт, 20 июл. 2021 г. в 20:24, Konstantinos Poulios
<[email protected] <mailto:[email protected]>>:
Dear Egor,
Ok I suspected that you might be in 3D, but referring to
"quad" made me assume that you were asking about 2D. In this
case, the question is more tricky because GetFEM's
architecture does not support 1D integrals in a 3D mesh. As
you probably know, mesh regions can only contain convexes and
convex faces. Integration methods are also defined only in
convexes and convex faces. Hence I am not very positive that
a solution exists based on the same 3D mesh.
The only solution that I see is by creating a 2D mesh from
your 3D mesh. E.g. you could define a 2D mesh that contains
all faces of a 3D simplex, and then integrate on the faces
(i.e. edges of this 2D mesh). Or alternatively, you can also
directly create a 1D mesh in 3D, based on the edges of your
3D mesh, but these are more difficult to extract.
In any case, working with 2 meshes, one 3D mesh, and one 2D
(or 1D) mesh, will require you to transfer information
between meshes using the different interpolation functions in
GetFEM, e.g. using an identity interpolate transformation:
image.png
I hope that this helps you decide about a strategy and please
ask again if you need help at lower level with the
implementation of such a strategy. I have a vague impression
that this question has also been discussed in the past in the
mailing list, so you might be able to find some tips in older
posts as well.
Not sure why the edges python function is marked as
deprecated. @Yves: Do you have a hint on that?
In any case relevant code in C++ can be found in
https://git.savannah.nongnu.org/cgit/getfem.git/tree/interface/src/getfemint_misc.cc
<https://git.savannah.nongnu.org/cgit/getfem.git/tree/interface/src/getfemint_misc.cc>
(build_edge_list)
https://git.savannah.nongnu.org/cgit/getfem.git/tree/src/bgeot_mesh_structure.cc
<https://git.savannah.nongnu.org/cgit/getfem.git/tree/src/bgeot_mesh_structure.cc>
(mesh_edge_list)
But these are quite low level functions.
Best regards
Kostas
On Tue, Jul 20, 2021 at 12:20 PM Egor Vtorushin
<[email protected] <mailto:[email protected]>> wrote:
Kostas,
thank you for answering thу question and sorry for the
delay in communication. I am sorry for missing
important point - i am in 3D space
In 2D HHO example it works fine since
|# # Boundary selection
|flst = m.outer_faces() GAMMAD = 1 m.set_region(GAMMAD, flst)||
managing with 1D faces that are the edges I suppose.
In 3D all_faces provides access to 2d faces. Consider 4
points simplex that have 4 faces. I can integrate over
an area of one of faces or many using regions built with
outer_faces output.
In my situation I have to make 1D integration over edges
with respect to length. The4 point simplex has 4 faces
and 6 1D edges.
|At first glance outer_faces() method doesn't provide
access to 1D edges for 3D meshes and with is my problem,
assuming the fact that it returns empty array for dim=1
or dim=2 |
|*boxm*.outer_faces() Out[: array([[0, 0, 0, 0, 0, 0],
[0, 1, 2, 3, 4, 5]], dtype=int32)
*boxm*.outer_faces(3) Out: array([[0, 0, 0, 0, 0, 0],
[0, 1, 2, 3, 4, 5]], dtype=int32)
*boxm*.outer_faces(2) Out: array([], shape=(2, 0),
dtype=int32) *EMPTY**boxm*.outer_faces(1) Out: array([],
shape=(2, 0), dtype=int32)|
|
|*EMPTY*||
||
|Here *boxm *is 1 convex rectangular |PARALLELEPIPED
|Regards, Egor|
||
пн, 19 июл. 2021 г. в 15:31, Konstantinos Poulios
<[email protected] <mailto:[email protected]>>:
Dear Egor Vtorushin,
Have a look at the outer_faces method:
image.png
if you put only one element in CVIDs you will get
what you want, I guess.
I am not sure how efficient it is to calculate these
integrals for all elements one by one though.
"mesh.all_faces" might also be relevant for your
question. You can also have a look at HHO examples like
https://git.savannah.nongnu.org/cgit/getfem.git/tree/interface/tests/python/demo_elasticity_HHO.py
<https://git.savannah.nongnu.org/cgit/getfem.git/tree/interface/tests/python/demo_elasticity_HHO.py>
Best regards
Kostas
On Mon, Jul 19, 2021 at 8:59 AM Egor Vtorushin
<[email protected] <mailto:[email protected]>> wrote:
Dear Yves,
Do you have any hints how to manage 1D integral
over a loop containing simplex' or quad' *edges*.
Let I have an electrical field(or current )
computed in simplex or quad mesh nodes. Then i
need to calculate the field circulation over
edge-loop for each *face *according to Stokes'
theorem/formula
There is an obsoleted function
|edges|(/CVLST=None/, /*args/)
Synopsis: [E,C] = Mesh.edges(self [, CVLST][,
‘merge’])
[OBSOLETE FUNCTION! will be removed in a
future release]
Return the list of edges of mesh M for the
convexes....
Maybe there is a way to utilize the Mesh.edges
function or another way?
Regards, Egor Vtorushin
