Use Free Triangular () to create an unstructured triangular mesh on boundaries in 3D and domains in 2D, as shown in Figure 8-61. The Free Triangular operation can also be used to remesh faces of imported surface meshes in 3D.

You can control the number, size, distribution, and refinement of elements by using Size, Size Expression, Distribution, and Corner Refinement subnodes (only Size and Distribution subnodes are available for Finalizing the Mesh).

For a mesh that defines its own geometric model, use Free Triangular to remesh one or several faces. The operation separates the selected boundaries from the mesh, creates a geometry from the separated mesh, meshes the geometry, and then copies the new generated mesh onto the original imported mesh. This operation has the following practical implications:

To add a Free Triangular node, select one or several boundaries (3D) or domains (2D) in the Graphics, then choose one of the following:

Define the boundaries (3D) or domains (2D) where you want to create an unstructured triangular mesh. Choose the level of the geometry from the Geometric entity level list:

For imported meshes in 3D, the available options in the Geometry entity level list are Manual and All boundaries.

To scale the geometry during the meshing operation, change the x-scale, y-scale, and z-scale in 3D to positive real numbers, as shown in Figure 8-62. If any of the scale factors are not equal to one (1), the software scales the geometry in those directions before meshing. After meshing, it restores the geometry and mesh to fit the original size.

The scale factors make it possible to generate meshes that are anisotropic, and is one alternative to use if the mesh generator creates many elements due to a thin geometry or large aspect ratios in the geometry (compare the first and last mesh in Figure 8-62). Compare this to changing the Resolution of narrow region parameter in a mesh Size attribute to only affect the mesh size in narrow regions. In 3D, consider using the Collapse Face Regions or Remove Details to remove narrow regions, if these are not important to the simulation at hand.

Select the check box Resolve narrow domain regions to allow the element size to be smaller close to narrow domain regions, as shown in Figure 8-63. The surface mesh will be the same as if the Free Tetrahedral operation had been built in the adjacent domain. Clear the check box to generate a triangular mesh without accounting for narrow domain regions. The check box is selected by default for meshes that define their own geometric models, such as imported meshes, and is cleared by default for meshes that are conforming with geometry.

Select the Smooth across removed control entities check box to smooth the transition in element size across removed Controlling the Mesh Size Using Mesh Control Entities. You can specify the number of smoothing iterations in the Number of iterations field. In the Maximum element depth to process field you can specify the maximum element depth for the mesh points to be smoothed.

Here you can specify the triangulation method used when creating the triangular mesh. Select Automatic (default) to let the software use the method that is best suited for the geometry. Select Delaunay to use a method based on a Delaunay algorithm. This results in a mesh with more irregular structure. Select Advancing front to use a method based on an advancing front algorithm. This results in a mesh with more regular structure.

You can optionally simplify the mesh when remeshing faces in an imported mesh. The simplification can remove small defects typically present in mesh data from measurements, such as tomography, and it can speed up the process by removing unnecessary elements. The Simplify mesh check box is selected by default to enable simplification.

The Relative simplification tolerance (default value: 0.01) is relative to the dimensions of the entire geometry and specifies a global limit for how much the mesh can be modified. The Defect removal factor (default value: 1) is relative to the local feature size, as estimated by the algorithm, and is combined with the global limit to produce a limit for how much the mesh can be modified at a certain location. If the mesh contains many defects that you want to remove, you could try to increase the value of the Defect removal factor. If the mesh describes the desired geometry with high accuracy, you might want to decrease this factor instead.