Re-meshing of parts of the domain with tetrahedral elements

In many cases, a layered FEFLOW mesh using prismatic elements will be the basis for a partially unstructured mesh. On the one hand, this option covers cases where a legacy FEFLOW model is to be extended by new features benefitting from unstructured meshing, on the other hand also newly built models may be much easier to handle with largely structured geometry in the vertical, and unstructured meshing only in specific locations where needed.

For this option, a classic layered mesh is built as detailed in the Supermesh design and Mesh generation descriptions. Having set up a 3D layered model, the following steps can be done to replace part of the mesh by using unstructured mesh geometry:

• Create a stored elemental selection of the zone you would like to replace the mesh in, and/or load 3D maps to the Maps panel that you intend to use as add-in geometry for the mesh generation.

Maps can also be used to determine the zone to be remeshed, without using an element selection.

• Move the stored elemental selection into the section From Element Selection of the Meshing panel.
• Move any maps to be used in the process to the section From Maps of the Meshing panel.
• Choose appropriate properties for the selection as well as the maps (described in the description of the Meshing panel).
• Generate the tetrahedral mesh using the Meshing panel.

When regenerating the mesh for parts of the model domain, the existing model parameters (process variables, boundary conditions and material properties) are inherited to the new elements. Make sure to check the result of the process, as general inheritance rules may not always be appropriate for the case at hand.

By generating an unstructured mesh for parts of the model domain, the previous layer/slice structure is not completely retained, but the mesh is handled as unstructured geometry in FEFLOW. This means, for example, that the Entities panel does no longer allow access to layers and slices. It offers, however, access to the tops and bottoms of layers in structured parts of the model. Slice views also only show the structured parts of layers and slices, parts with unstructured geometry show as holes and their parameters can only be edited in 3D views. The elements in the pinching zones of the model can be addressed by Element Groups that are automatically created in the Entities panel. Additional layers/slices cannot be added to partially unstructured meshes.