Pinch controls are not supported.

Only three-dimensional bodies can be used as Bodies of Influence (BOIs).

The hard-sizing behavior of Sphere of influence (SOI) controls is not supported. You can define a refinement with an SOI control but not a coarsening. The SOI element size is only applicable in the mesh if it is smaller than the local mesh size without SOI.

BOI controls are interpreted as an agglomerate of SOI controls that fill the body of influence. Therefore, on the boundaries of that body, the size might be a little larger because the location is not in one of the spheres.

The scope is not used for the SOI/BOI definition. The SOI/BOI does not act only on the scoped topology, but on all topologies within the region of the SOI/BOI.

In MultiZone, size controls are first applied on the edges. For structured blocks, the mapped mesh of structured blocks is completely determined by the mesh on the attached edges. You cannot apply refinement or coarsening to the faces as you can for unstructured blocks. Therefore, to see the impact of the SOI on a mapped face, you must increase the radius of the SOI or lower the Growth Rate to influence the mesh size on the edges. 

Figure 177: Sphere of Influence on Face that Doesn't Intersect Edges

In MultiZone, a closed edge is represented by more than one blocking topological edges. Therefore, user-specified edge node distribution size may not be respected. However, the number of intervals will still be respected, 

For split curves in rotated edge association, only interval count, not distribution, will be respected.

Some inflation cases are not supported. For example, when the inflation does not form a closed loop (which would lead to non-conformal mesh that is not allowed). In these cases the inflation will be skipped. Also see MultiZone Support for Inflation.

The Show Sweepable Bodies feature is a good tool to detect bodies that should mesh with MultiZone.

There is no access to underlying blocks except by writing out the Ansys ICEM CFD files.

For help in diagnosing problems when using the MultiZone method, refer to the description of the Edge group in the Mechanical help. This toolbar provides access to features that are intended to improve your ability to distinguish edge and mesh connectivity.

See Handling General MultiZone Meshing Failures for more information.