# 1.2 Methodology

In the two-dimensional case, it corresponds to (according to the MODULEF approach):

• generating meshes from point, line, contour, course mesh, 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 achieve 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;
• record, furthermore, the primal sub-sets 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 and lines 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;
• perform some local or global transformations (refinement, regularization, etc.);
• 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 deformed quadrilateral or triangle, modules TRICOO and QUACOO (algebraic methods ) generates quadrangles, which can be split into triangles, and triangles;
• for an arbitrary domain, modules TRIFRO and TRIHER (advancing-front method  and Voronoi's method ) generates triangles;
• similarly, COLIB2 (multi-block method ), in the 2D version, produces the same result from a partitioning of a course mesh of the domain.
• when the elements to be created are few or identical, module CONOPO (manual method ) could be used;
• CONOPO is suitable to mesh lines into segments;
• MAOBJE is used to treat catalogued objects.

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