3D Supermesh Preprocessing

FEFLOW 10.0 offers a first level of access to tools and methods dedicated to the building and repairing of 3D surfaces and polylines, allowing the explicit and implicit creation of geological / structural geometric models. The Geode-FEFLOW tools in FEFLOW 10.0 are accessible via the Supermesh Processing panel. The tools are Repair Surfaces, Re-triangulate Surfaces and Generate Implicit Surfaces. For further details about Geode-Solutions technologies visit the company Website.

The Geode-FEFLOW tools as part of FEFLOW Advanced module (from v. 3.0x) are only supported with the new 3D Supermesh data structure (*.smh3d). FEFLOW Advanced module requires a separate license to the FEFLOW license. FEFLOW Advanced is part of the Software Maintenance Agreement (SMA) benefits.

In case you have an old 3D Supermesh file (*.smhx), you would need to firstly save the document as *.smh3d in order to use methods such as surface repair, surface remesh, volumetric mesh and implicit modelling.

The Supermesh Preprocessing panel with Geode-FEFLOW tools.

Explicit Methods

Relying on the state-of-the-art technology developed by Geode-Solutions, 3D Supermeshes can be processed in different orders to achieve:

Surface/surface and surface/polyline intersections allowing the creation of a 3D geometric models from sets of independent surfaces, polylines, and points.
Remeshing of 3D triangulated surfaces, targeting both triangle equilaterality and user input mesh size metrics.
Simplification of 3D triangulated surfaces.
Generation of volumetric regions for 3D tetrahedral meshing with TetGen (see section 3D Meshing) or Geode.

Geode-Solution’s embedded technology aims at guaranteeing the conformity and quality of 3D geometric data, the basic requirements for a robust 3D triangulation towards an optimal 3D unstructured finite element mesh.

Depending on the 3D dataset, the tools can be used independently or in combination. Here is an overview of the possible workflows and tool selections:

Workflow	Description
Repair Surfaces only	The Repair Surfaces is used to identify and resolve the intersections. Then the 3D Supermesh is ready for tetrahedrization with Geode or TetGen.
Re-triangulate and then Repair Surfaces	The Re-triangulate Surfaces option is used to improve the equilaterality of the imported triangulated surfaces. But the surfaces still do not fulfil a proper boundary representation. Subsequently, Repair Surfaces is used to identify and resolve the intersections. Finally, the 3D Supermesh is ready for tetrahedrization with Geode or TetGen.
Repair Surfaces and then Re-triangulate	The Repair Surfaces is used to identify and resolve the intersections. The 3D Supermesh now consists on a proper boundary representation. Subsequently, the Re-triangulate Surfaces option is used to improve the triangulation of the inner and outer surfaces. Finally, 3D Supermesh is ready for tetrahedrization with Geode or TetGen.
Re-triangulate only	One or multiple surfaces has been imported to the 3D Supermesh project. Re-triangulate Surfaces option is used to improve equilaterality of the triangles only. Resulting triangulated surfaces do not necessary conform a proper boundary representation ready for tetrahedrization.

Although the Re-triangulate Surfaces is very practical option for improving the equilaterality of the surfaces, the fact that the mesh is optimized, it means also that topological (and geometrical) details can change. Moreover, in the cases that multiple uses are re-meshed, Re-triangulate Surfaces tool does not verify whether the resulting surfaces are intersecting (or not). Under some specific geometrical configurations, it will be required a subsequent re-run of the Repair Surfaces algorithm.

Original Supermesh	Repair Surfaces	Repair and Re-triangulate Surfaces

Repair Surfaces

Option	Description
Filter outer surfaces [True / False]	The Repair Surfaces algorithm is capable to identify surfaces within or outside the general boundary representation. By activating this option, the algorithm will remove all the surfaces or part of them located outside the domain boundaries.
Sharp angle [°]	Surfaces are individualized by default. The criteria used for the individualization depends on the user-defined sharp angle. The angle range from 0° to 179.9°. The default and recommended value is 120°.

Re-triangulate Surfaces

Option	Description
Preserve original vertices [True / False]	Option defines whether the original vertices of the surfaces should be preserved or not. Prevent vertices and segments of the input geometries to be removed within planar regions. Some input configurations may produce results exhibiting external hulls being too deeply modified on output, in which case the option should be used.
Sharp angle [°]	Dihedral angle beyond which planarity of triangles sets is considered. When attempting to preserve original vertices and segments during surface re-meshing, this limit angle allows for planar regions to be re-meshed without unexpected and exaggerated modifications of the external border shape. The angle range from 0° to 179.9°. The default and recommended value is 120°. Larger the sharp angle is, lesser the modifications of the resulting mesh compared to the original surface are.
Global edge size [m]	The desired length of generated triangles edges. If the value is left to 0 [m], then FEFLOW proposed an edge size based on the minimum and maximum sizes of the surface (s) used for the operation.

Implicit Modelling Methods

In combination with the explicit methods for surface preprocessing such as Repair Surfaces and Re-triangulate Surfaces, FEFLOW 10.0 provides an alternative and robust workflow using implicit modelling methods for building the structural geology. Based on field observations such as boreholes and boundary representations, the Generate Implicit Surfaces option under Supermesh Preprocessing panel. The use of implicit modelling methods in FEFLOW 10.0 is separately discussed in the section Implicit modelling.