4.5.3.4 Definition of Simulation Grids

PROMIS-NT is capable of performing its simulations on either orthogonal or unstructured triangular grids. In both cases the simulation grid is derived from the input grid by applying some quality criteria given by interface parameters of the PROMIS-NT setup model instance. The according PromisNTSetupModel Parameters are listed in Table 4.9. If more then on grid is defined within the input PIF file, the Parameter inputGRID can be used to select the initial simulation grid explicitly.

Table 4.9: PROMIS-NT simulation grid setup

Name	Type	Description
inputGRID	MdlString	Input PIF grid object used as initial grid for simulation. This grid must be an overall grid.
useOrthoProduct	MdlBool	Perform simulation on ortho product grids. Default: false
sectioAurea	MdlBool	Use this ratio to refine the grid before the simulation is started. For any number smaller then the golden ratio (i.e. sectio aurea, 1.618...) the golden ratio is used, which gives the finest automatically generated grid. As larger the ratio as coarser the generated grid. The coarsest grid is the initial grid itself. Default: 0.0
triangleAreaFrac	double	absolute area fraction used as limit for refining one triangle Default: 0.2
maxTriangleArea	double	absolute maximum area for triangles in ${\mu}m^2$ as limit for refining one triangle Default: -1.0
generateDelaunay	MdlBool	generate a new Delaunay grid or compute on existing input grid Default: true
minTriangleArea	double	absolute minimum area for triangles in ${\mu}m^2$ as limit for refining one triangle Default: 5e-4
minAngle	double	minimum angel for quality mesh generation Default: 20.0
coarseError	double	absolute error factor for coarsing grid refinement criterion Default: 5e-2
doseError	double	absolute dose error factor for dose refinement criterion Default: 3e-3
curveError	double	absolute gradient error factor for transient gradient refinement criterion Default: 1e-3
gradError	double	absolute gradient error factor for transient gradient refinement criterion Default: 1e-3
gridAdaption	MdlString	MDL class for user defined grid adaption.

The usage of an orthogonal simulation grid can be enforced by using the Parameter useOrthoProduct. In case an orthogonal grid is used the sectioAurea defines a simple quality criterion ensuring that the grid density does not vary too much [47].

Triangular grids can either be created from scratch (generateDelaunay) or refined from initial input grids by utilizing the built-in TRIANGLE library. Detailed informations about the applied quality criteria can be found in [52] and [4].