Question
Error message saying "A self-intersection was detected" when trying to generate the unstructured mesh with the TetGen - mesh generator (see Fig. 1). Why does this happen?
Fig 1 - Error message "A self-intersection was detected"
Answer
The error may be triggered by an intersection of geometries.
There are two types of intersections not allowed in the TetGen mesh generator - polylines cutting through an elemental facet or entire polygons cutting facets (see Fig 2. and Fig. 3). If this is the case, it is best practice to return to the supermesh and repair the intersections there. You can also take an entire step back and fix the surfaces inside your geological software.
Fig. 2 - Example of intersection not allowed in the TetGen mesh generator
Fig. 3 - Example of intersection not allowed in the TetGen mesh generator
Fig. 4 - Geometries with no holes and no intersection/overlapping. The example is imported from GOCAD.
FURTHER INFORMATION & USEFUL LINKS
Manuals and Guidelines
FEFLOW 8.1 Documentation - Supermesh 3D