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2.2 Methodology

For the three-dimensional case, it corresponds to:

• generating meshes from point, two-dimensional meshes, coarse meshes, etc., data, using the appropriate algorithms;
• modifying existing meshes and combining them to form the final mesh, step by step, to which a D.S. of type NOPO is associated. This D.S. is then stored in a sequential access file.

In order to perform the above steps, we need to:

• locate all the primal sub-sets in the domain by eliminating all sub-sets which can be derived by symmetry, translation, etc., or more generally, by geometric transformation;
• locate the domains which can be derived from a two-dimensional mesh of one of its sections;
• record, furthermore, the primal subsets linked to physical type constraints;
• search for the module which is the most suitable for each of these sub-sets;
• determine the nature of the data which each of these modules use;
• construct the data from the points, ..., present;
• activate the desired mesh generator(s);
• perform the symmetries, translations, rotations, etc., of the primal sub-sets;
• "glue" these meshes together, two by two;
• repeat the two previous steps until the entire domain is covered;
• split the elements into tetrahedra or into sub-elements of the same type, if desired;
• define the non-vertex nodes, if necessary, and remove the vertices from the nodal list;
• renumber, if necessary, the elements and/or nodes;
• store the result on file (and plot it to verify and ensure the quality of the mesh).

For each primal sub-set, we select the module which is most suitable:

• for a topologically hexahedral domain, we use, excluding APNOP3, module GEL3D1 (see chapter 3);
• For a topologically cylindrical domain, we use module MA2D3D (see chapter 3, or keyword MA23 of APNOP3);
• for an arbitrary domain, module COLIB2 (multi-block method), or the corresponding processor COLIXX, is used excluding APNOP3 (see chapter 3);
• when the elements to be created are few or identical, module CONOPO (manual method) could be used;
• module MAOBJE is used to treat catalogued objects;
• for all cases where the mesh is created not using APNOP3, if the mesh must be used for fine manipulations, SDREST is used to introduce this mesh into memory and manipulate it via the different possibilities presented by APNOP3.