9.1.3    Meshing hazards along the Z-axis

Let us recall that at the level of bottom and cover of each element the software automatically creates Mesh Snapping Planes. If the mesh generator detects two such Mesh Snapping Planes, enforced by two different elements, at different levels but very close to each other – it will create a very thin layer of cells. What may happen in some specific cases is that these two levels should really be identical, and they have been shifted apart as a result of previous operations on elements. The difference may also arise when we have two elements, at the same physical level and of the same physical height, but one of them is simple while the other - combined. For the combined element the levels of bottom and cover are explicitly remembered by QW-Editor. For the simple element, QW-Editor remembers its height and the level of bottom, and calculates the level of cover therefore. The result may be different from the level of cover of the combined element.

The thin layer of cells created in such cases would be unnecessary, prolonging the simulation time and deteriorating the accuracy. To avoid such problems, QW-Editor precedes the actual mesh generation by snapping of all coordinates to 10^-6 in current units. This measure has proven sufficient in all typical applications, but nevertheless the user is advised to consult the Mesh Info dialogue whenever substantial changes in the project have been made.