Layer Pinching Workflow

This section provides some guidelines for the workflow of a specific case of re-meshing parts of the domain with an unstructured mesh (layer pinching) by using the 3D Layer Configuration dialog.

Starting from a layered or 2D mesh, the following steps need to be done to set up a 3D partially structured mesh with layer pinching. Please note that the steps described, and especially their order, can only be an example as the exact procedure is highly dependent on the situation at hand, and will typically include an iteration of several steps.

Open the 3D Layer Configuration dialog.
Create the desired number of slices using the tool buttons.
In case that the elevation assignment that will follow in the next step will cause intersections, the Class setting in the slice list determines which slice will prevail. By default, Fixed and Moveable are available as settings, with Fixed slices keeping their assigned elevations and Moveable slices being adapted. So attribute all the slices with appropriate settings, following typically their geological genesis.

A user-defined finer gradation of the so-called Horizon Classes can be created by using the tool buttons below the slice list.

Attribute the different slices with elevations, either by using a homogeneous elevation that can be typed into the Elevation column of the slice list, or by using Apply elevations... in the toolbar or in the context menu of a slice.
For the latter case, a point map loaded to the maps panel before can be chosen to provide elevation data for the slice, along with settings of an interpolation method defining how the regionalization is done.

If a point map containing elevation data for all slices rather than one map for each slice is available, this can be applied to the root of the tree list view (Slices). The map is required to contain an attribute called 'Slice' that contains the slice number in this case.

Both 3D view and Elevations tabs show the actual status of the model elevations as a preview. The original model is not changed until the OK button is hit.
In case that the elevation assignment causes intersections, the Class setting in the slice list determines which slice will prevail. By default, Fixed and Moveable are available as settings, with Fixed slices keeping their assigned elevations and Moveable slices being adapted.
Repeat the above steps in an iterative process if necessary.
Once the structure is as desired, click on OK to apply the changes transfer the elevation and layer structure setup to the actual model.
In case there are slice intersections, the upcoming Layer resolution dialog allows to select an option for repairing the geometry.
Choose either the second or third option to resolve the conflicts with layer pinching. The uppermost option would repair the geometries by using continuous layers.

As for more complicated cases a complex order and a large number of steps may be required, the 3D Layer Configuration dialog allows to record the steps being done as a macro and repeat them by executing the macro. See Using a Macro to Build the 3D Mesh.

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.