One method to obtain a grid of triangles in the simulation domain is to use the
DELAUNAY criterion^{3.3}: Given any set of points distributed over
a simulation domain, the DELAUNAY criterion requires that the sum of two facing
angles obtained from a triangulation is never larger than . However, the plain
DELAUNAY algorithm must be supplemented by a number of empirical constraints, which
become necessary when dealing with internal interfaces. Moreover, since the algorithm works
on a pre-defined set of points, a local grid refinement requires the entire tessellation to be
repeated. More details according to DELAUNAY triangulation can be found in
[54].

Another method to get a simulation grid is to use a regular mesh structure within the device
inner region, such as a rectangular grid. A set of nested rectangles can be used to modulate
the mesh point density^{3.4}. Local refinements can be easily performed by splitting any given rectangle
into two or four smaller elements. The rectangle set can be easily converted into a set of
triangles by diagonalization [11, p.72].