5. Operand OPERATION = “COLLAGE”#

The “COLLAGE” operation is used to connect two meshes that would have been meshed independently in two separate files (for example by two different teams).

If the two meshes are not consistent on their interface (different discretization), the user will have no choice but to use the AFFE_CHAR_*/LIAISON_MAIL feature to link the degrees of freedom of the two meshes that will remain topologically disjoint. He will then have to use the “SUPERPOSE” operation.

If, on the other hand, the two meshes have been planned to be glued back together, it will use the “COLLAGE” operation. To do this, he should have taken the precaution of naming the two groups of (interface) meshes that will allow the two meshes to be glued together. In addition, these two groups of cells must be geometrically coincident. The user will then write:

OPERATION =” COLLAGE “, COLLAGE = _F (GROUP_MA_1 =”gma1”, GROUP_MA_2 =”gma2”,),

The mesh groups gma1 and gma2 will then be merged. More specifically:

  1. the gma1 and gma2 meshes will be removed,

  2. the gma2 nodes will remain (but will be orphans),

  3. the nodes in gma1 will connect the two meshes.

Before merging the two mesh groups gma1 and gma2, the code will check that the nodes of these two mesh groups are coincident (with a tolerance of \(\mathrm{0,001}\) times the length of the smallest edge of the two meshes).

Entity name conflicts in the two meshes are resolved in the same way as for the “SUPERPOSE” operation (see above).