Med Memory Users' Guide 5.1.3

MESH

General information

The MESH class is dedicated to the handling of unstructured meshes. Two classes derive from it : MESHING supplies functions for creating meshes from scratch (c.f. MESHING), while GRID gives specific constructors for creating structured meshes.

Content of the connectivity array

Underlying the unstructured meshes is the notion of connectivity. This section only covers meshes made out of standard elements, the MED_POLYGON and MED_POLYHEDRA case being detailed in section Polyhedra and polygons .

connectivity_arrays_small.png

Nodal connectivity storage scheme

In MEDMEM, an unstructured mesh nodal connectivity is defined with these arrays (if the mesh has no MED_POLYGON and MED_POLYHEDRA element) :

  • the type array, which contains the number of cells for each present type
  • the nodal connectivity array containing the connectivity of each cell, all cells being sorted by type,
  • the connectivity index array, which indicates the beginning of each cell in the connectivity array,

The cell types are ordered by their number of nodes.

As an example, let us consider a mesh made out of a linear triangle, two linear quadrangles and a quadratic triangle (c.f. figure fig_connectivity_example ).

connectivity_example_small.png

Example for mesh connectivity

The number of types is : 3

The type array writes : MED_TRIA3, MED_QUAD4, MED_TRIA6