There are three primary advantages to using the projection method in building block structured hexa meshes. The advantages are all related to the inherent limitations in CAD geometry. A typical 3D CAD model has 3D curves and surfaces or solids consisting of 3D surfaces. A single surface is usually not convenient for such a mesh. So the first advantage is that multiple surfaces can be combined to form one face of a block structure. These surfaces that form a composite usually do not meet perfectly. The second advantage of the projection method deals with these imperfections in composites. The third advantage of the projection method is when an block mesh edge needs to be at the intersection of two surfaces which do not meet properly.
When a node is projected to a composite surface, first it is projected to each individual surface. Then the projection that is closest is chosen as the projection point. It will always project to a point on one of the surfaces.
If you project two faces with a common edge onto two different surfaces (respectively) that almost intersect, then TrueGrid® will place the edge nodes along the intersection of the tangential extension of the two surfaces.
Most mesh generators require that the CAD geometry be cleaned up or healed before it can be used. A lot of time and money can be spent in this process. TrueGrid® automatically compensates for these imperfections so that the clean up process can skipped.
