Editing Input syntax manual (section)

=== voro (stochastic Voronoi tessellation geometry definition)<span id="voro"></span> ===

 '''voro''' ''UNI<sub>0</sub>'' ''UNI<sub>bg</sub>'' ''R<sub>0</sub>'' '''-1''' ''NP'' ''UNI<sub>1</sub>'' ''VF<sub>1</sub>'' [ ''UNI<sub>2</sub>'' ''VF<sub>2</sub>'' ... ]

 '''voro'''  ''UNI<sub>0</sub>'' ''UNI<sub>bg</sub>'' ''R<sub>0</sub>'' ''FILE''

Defines a stochastic Voronoi tessellation geometry. Input values:

{|
| <tt>''UNI<sub>0</sub>''</tt>
|: universe name for the Voronoi medium
|-
| <tt>''UNI<sub>bg</sub>''</tt>
|: background universe name filling all undefined space
|-
| <tt>''R<sub>0</sub>''</tt>
|: test radius [in cm]
|-
| <tt>''NP''</tt>
|: number of seed points
|-
| <tt>''UNI<sub>m</sub>''</tt>
|: sub-universe name for the ''m''-th random fragmented polyhedral zone
|-
| <tt>''VF<sub>m</sub>''</tt>
|: volume fraction associated to ''m''-th random fragmented polyhedral zone
|-
| <tt>''FILE''</tt>
|: input file containing the Voronoi data
|}

The <u>syntax of the file</u> containing the Voronoi seed points data is:

::{| class="toccolours" style="text-align: left;"
|-
| ''X<sub>1</sub>'' ''Y<sub>1</sub>'' ''Z<sub>1</sub>'' ''UNI<sub>1</sub>''
|-
| ''X<sub>2</sub>'' ''Y<sub>2</sub>'' ''Z<sub>2</sub>'' ''UNI<sub>1</sub>''
|-
| ...
|-
| ''X<sub>N</sub>'' ''Y<sub>N</sub>'' ''Z<sub>N</sub>'' ''UNI<sub>1</sub>''
|-
| ''X<sub>N+1</sub>'' ''Y<sub>N+1</sub>'' ''Z<sub>N+1</sub>'' ''UNI<sub>2</sub>''
|-
| ...
|}

where:
{|
| <tt>''X<sub>n</sub>'', ''Y<sub>n</sub>'', ''Z<sub>n</sub>''</tt>
|: seed points coordinates [in cm]
|-
| <tt>''UNI<sub>m</sub>''</tt>
|: sub-universe name for the ''m''-th random zone associated to the given seed point
|}

<u>Notes:</u>
*The input consists of a list of seed points and associated sub-universes filling the Voronoi cells Alternatively, the number of seeds points and volume fractions of each zone can be provided, letting Serpent sample the positions randomly.
**The advantage of the first option is that the distribution can be defined explicitly, taking into account, for example, the varying level of fragmentation closer to the boundaries.
*The cell search and surfaces distances are based on search mesh and local short-list of points to reduce the computational effort. 
**The search mesh is conditioned by the test radius, which should enclose the Voronoi polyhedral cells.
***Too small radius may result in geometry errors as some points are excluded from all the search mesh cells in which they should be.
***Too large radius may results in including points in cells that do not actually intersect with the polyhedral boundary.
*The <tt>''DENS''</tt> parameter in the [[#set mcvol|mcvol]] input option can be switched "<tt>on</tt>" to compensate the non-preservation of the volume fractions provided as input due to the randomness of the seed points.
**It applies calculated scaling factors to material densities preserving the original masses (scaling factor = volume MC routine / volume given)
*The stochastic geometry type based on Voronoi tessellation is described in related paper<ref>Leppänen, J. ''"A New Stochastic Geometry Type Based on Voronoi Tessellation in the Serpent 2 Monte Carlo Code."'' In proc. M&C2023, Niagara Fall, Canada, Aug. 13-17, 2023</ref>.