Originally Posted by PSYMN

Hex Dominant doesn't really play well with the other methods. You will also have a hard time when you try to merge it with the Hexa method, so you will need to do things in the right order...

Hex Dominant is also really more of an FEA method. It starts from the quad surface mesh and grows into the middle. If you don't have a quad surface mesh, it surface meshes everything first and then starts. It doesn't do the material point flood fill that the octree tetra mesher does. It could give perfect hexa on this simple case, but I am guessing yours is more complicated and you may not like all the junk pyramids and tetras in the middle.

If you are sure you want to go with this mesher, you should probably go the other way around... Do the Hexa blocking side first... Then save that mesh. Then delete all the mesh except the faces that touch the portion you want to hexa dominant mesh... (this will be the seeded surfaces).

Then surface mesh the rest of the region you want to hexa mesh (you can actually select the surfaces to mesh), make sure to turn on the option to "respect line elements" since this will let your new surface mesh connect properly to your previous surface mesh...

Run the Hexa Dominant mesher from the existing mesh... Save that mesh file.

Then load the Blocked Hexa mesh... It will ask if you want to replace or merge, choose merge to concatenate the files... Since the interface mesh came from the hexa blocking mesh, it will be exactly aligned, but you still need to merge the nodes. Use Edit mesh => Merge Nodes => Tolerance. Set the tolerance to something very small (like 0.0001) and apply.

Then you can delete that interface surface mesh since you won't need it any more...

Save the combined mesh and output to your solver.

Have fun with it.