Aligned Meshing and Geometric Features

In the surface remesher, aligned meshing is a fully automated process which creates a template mesh on surfaces with four corners.

Aligned meshing improves the surface mesh representation for 4-sided surfaces, such as fillets and rounds, especially when they are meshed with a coarse mesh. Other benefits include quicker CAD projection and a more efficient use of faces on the surface mesh.

For flat surfaces, the aligned mesher only produces an aligned mesh when the cells that are produced are of significantly higher quality than when using the regular remesher. For example, if the aligned mesher is likely to create poorly-shaped triangles, it automatically reverts to the basic remesher output for that CAD surface. For curved surfaces, an effort is made to align the mesh with the curvature. For this reason, Simcenter STAR-CCM+ often favors the aligned mesher, while allowing for some degradation in the cell quality, as it captures the geometry more effectively.

In the Surface Remesher model expert properties, the Create Aligned Meshes option is activated by default.

This feature is fully active in these situations:
  • Cases with CAD association, where the Project to CAD option is activated (default). The resulting meshes keep their CAD association.
  • Cases with CAD association, where the Project to CAD option is deactivated. CAD association is lost, but aligned meshing is performed.
  • Cases without CAD association of any kind, regardless of how you set the Project to CAD option.
You can generate aligned meshes on discrete surfaces. In this context, a discrete surface is defined as:
  • Surfaces with no CAD.
  • All surfaces in the surface remesher, if Project to CAD option is deactivated.
  • Any surface which is partially or fully disassociated from CAD coming into the surface remesher.

Limitations of Aligned Meshing

Limitations of the aligned mesher for surfaces with CAD:

  • The Create Aligned Meshes option works best with faces and vertices on surfaces that have 100% CAD association. If the surfaces have incomplete CAD maps, a hybrid projection is created. Local CAD projection is used when the information is available. When no information is available, a discrete projection is used back to the initial mesh.
  • When using Parts Based Meshing, geometric features are retained automatically.
  • You can use one or more feature edges as boundaries for aligned meshing, as long as there is only one underlying CAD surface.
  • For aligned meshing to be able to work on a surface, the surface must have at least four CAD vertices, four corners, or four feature edges surrounding the area of interest.
  • Surfaces that are directly on a periodic interface map are not aligned-meshed, even when only one edge is shared. However, in-place maps between neighboring parts can be aligned-meshed.
  • There must be no inner loops on the surface.
Limitations of the aligned mesher on surfaces with no CAD:
  • The limitations that apply to aligned meshing on surfaces with CAD also apply to aligned meshing on surfaces with no CAD.
  • Aligned meshing supports 4-sided and non-4-sided rectangular surfaces, however these surfaces must have 4 distinct corners.
  • Aligned meshing is based on patches. More specifically, any discrete region is a candidate for aligned meshing if this region is 4-sided and is surrounded by patch perimeters, part surface boundaries, and/or feature edges.
  • Aligned meshing works for models that have a combination of regions/surfaces that are associated with CAD and other regions/surfaces that are not associated with CAD. In such situations, surfaces that are associated to CAD are aligned and remain associated to CAD, and the discrete surfaces are also candidates for aligned meshing, but are projected to the initial mesh.
  • Cylinders, and other closed surfaces that have 0 or 1 seams, are not aligned if they are discrete but are still supported if they have underlying CAD. To make sure that these surfaces are aligned, break them into at least 2 separate patches/surfaces—by default, Simcenter STAR-CCM+ does this for cases with CAD. You can break these surfaces into 2 or more surfaces using feature edges.