How to build a 3D multimesh?

Hello

I’m relatively new to working with Fenics, and I’m using it for overlapping meshes. So far I haven’t had big problems working with 2D multi-meshes, however, for 3D meshes it hasn’t been possible to build a multimesh. I’m sending you a brief example along with the error. In the article https://arxiv.org/pdf/1610.02277.pdf they describe a successful case using 3D overlapping meshes in Fenics, however it doesn’t work for me. Thanks for any advice.

The example:

from mshr import *
from dolfin import *

SphereTest = Sphere(Point(0.0,0.0,0.0),5.0)
front_mesh = generate_mesh(SphereTest, 10)
front_mesh1 = generate_mesh(SphereTest, 10)
VectorP=Point(0.0,0.0,5.0)
front_mesh.translate( VectorP)

multimesh = MultiMesh()
multimesh.add(front_mesh)
multimesh.add(front_mesh1)
multimesh.build()

The error:

Generating mesh with CGAL 3D mesh generator
Generating mesh with CGAL 3D mesh generator
Traceback (most recent call last):
File “3D_Sphere.py”, line 23, in
multimesh.build()
RuntimeError:

*** -------------------------------------------------------------------------
*** DOLFIN encountered an error. If you are not able to resolve this issue
*** using the information listed below, you can ask for help at


*** fenics-support@googlegroups.com


*** Remember to include the error message listed below and, if possible,
*** include a minimal running example to reproduce the error.


*** -------------------------------------------------------------------------
*** Error: Unable to triangulate convex polyhedron.
*** Reason: Triangulation of polyhedron of topological dimension 2 and geometric dimension 3 not implemented.
*** Where: This error was encountered inside ConvexTriangulation.cpp.
*** Process: 0


*** DOLFIN version: 2019.1.0
*** Git changeset: 15b823f2c45d3036b6af931284d0f8e3c77b6845
*** -------------------------------------------------------------------------

Best regards,

The collision detection algorithms for 3D MultiMesh was never merged in to the master branch of dolfin. I would contact the authors of that paper to obtain their 3D version of the software.

Thank you for your quick response. It would really help a 3D multi-mesh version of the software. I have some problems I wish I could run.

Best regards,

You should send one of the authors an email.