Difference between revisions of "Unstructured mesh-based geometry type"

From Serpent Wiki
Jump to: navigation, search
(Mesh structure/quality)
(Splitting of polyhedrons)
Line 79: Line 79:
  
 
=== Splitting of polyhedrons ===
 
=== Splitting of polyhedrons ===
 +
 +
Serpent will do the final neutron tracking in a tetrahedral mesh, which is automatically generated by splitting other polyhedrons to tetrahedra. Tetrahedrons are used in the neutron tracking as each of their face surfaces is defined by three points (the vertices of the face) this is exactly the number of points required to uniquely define a plane.
  
 
=== Debugging ===
 
=== Debugging ===

Revision as of 09:56, 26 February 2016

The unstructured mesh based geometry is a by-product of the unstructured mesh-based multi-physics interface. It can be used to create a geometry universe based on an unstructured mesh.

Input Syntax

The unstructured mesh based geometry can be created by using the solid 1 or solid 3 input card.

Geometry only (solid 1)

solid 1 UNI BGUNI
MESH_SPLIT MESH_DIM SZ1 SZ2 ... SZMESH_DIM
POINTS_FILE
FACES_FILE
OWNER_FILE
NEIGHBOUR_FILE
MATERIALS_FILE

The first solid type creates an unstructured mesh-based geometry universe. Input values are:

UNI  : universe name for the irregular geometry
BGUNI  : name of the background universe filling all undefined space
MESH_SPLIT  : Splitting criterion for the adaptive search mesh (maximum number of geometry cells in search mesh cell)
MESH_DIM  : number of levels in the adaptive search mesh
SZi  : Size of the search mesh at level i
POINTS_FILE  : Path to the unstructured mesh points file
FACES_FILE  : Path to the unstructured mesh faces file
OWNER_FILE  : Path to the unstructured mesh owner file
NEIGHBOUR_FILE  : Path to the unstructured mesh neighbour file
MATERIALS_FILE  : Path to the unstructured mesh materials file

Geometry and multi-physics data (solid 3)

solid 3 UNI BGUNI
INTERFACE_FILE

It is also possible to create the geometry and bring in temperature and/or density data on the same mesh. In this case, most of the parameters are given in a separate multi-physics interface file which can be re-read by Serpent to update the fields between coupled calculation iterations. The input values in the main input file are:

UNI  : universe name for the irregular geometry
BGUNI  : name of the background universe filling all undefined space
POINTS_FILE  : Path to the interface file containing the rest of the parameters


The input format of each of the linked files is based on the OpenFOAM file format.

Mesh structure/quality

The mesh can consist of arbitrary polygons as long as they can be entered in the OpenFOAM file-format and some quality requirements are met:

  • The cells must be closed
  • The cells must be convex (i.e. all face and body diagonals must be completely within the cell volume)
  • Each face must have exactly one owner cell.
  • Each face must have exactly one or zero neighbor cells.

Splitting of polyhedrons

Serpent will do the final neutron tracking in a tetrahedral mesh, which is automatically generated by splitting other polyhedrons to tetrahedra. Tetrahedrons are used in the neutron tracking as each of their face surfaces is defined by three points (the vertices of the face) this is exactly the number of points required to uniquely define a plane.

Debugging