DESCRIPTION OF A NON-STRUCTURED TRIANGULAR MESH

This mesh is defined giving a list of num_triangles triangles, num_nodes vertices. Each triangle is defined giving 3 vertex number. Contrary to previous triangular mesh, there is no defined edge structure. The mesh must be "rebuilt" : Each couple of points of a triangle (defining a virtual edge) must be referenced twice in the mesh, this means an edge must belong to two mesh elements. (this is a topological and not geometric reference). An edge which belong to only one mesh element is supposed to be on the border of the mesh (or on the skin of the mesh)

Data structure for non-structured triangular mesh is:

• num_triangles Number of triangles of the mesh.
• num_nodes Number of vertices of the mesh.
• triangle_nodes Array of the three indices pointing to nodes array, describing the triangle nodes.
• nodes Array of num_nodes coordinates of mesh nodes
• s Array of num_nodes values, one for each mesh node.
• v Array of num_nodes vectors, one for each mesh node.

Remark : The array nodes may include vertices which do not belong to any triangle of the mesh. In this case the mesh does not provide a continuous numeration of the vertices and num_nodes is not the total number of vertices of the mesh but the dimension of nodes array.

Sample triangular mesh with num_triangles = 8, num_nodes = 8:

1st vertex 0 1 1 6 2 7 5 1

2nd vertex 5 6 0 4 3 6 6 4

3rd vertex 6 4 6 2 4 2 7 3

triangle_nodes

0 1 1 6 2 7 5 1

5 6 0 4 3 6 6 4

6 4 6 2 4 2 7 3

Example : vertex 1 of triangle 5 is triangle_nodes [5][1] = 6