Duo (geodesic triangular)

Grid family
duo
Kind
grid
Source
src/grids/duo.jl
Tags
#grid #unstructured #triangular #icosahedral #geodesic

Description

The duo family is a geodesic triangular mesh — a recursively-bisected icosahedron projected onto the sphere. At level L, each of the 20 icosahedral seed faces is subdivided into 4ᴸ triangles, giving 20·4ᴸ triangles, 30·4ᴸ edges, and 2 + 10·4ᴸ vertices.

The mesh is unstructured (no (i, j) indexing) but enjoys topological regularity: every interior vertex has 6 incident edges and the only “defects” are the 12 vertices inherited from the icosahedron, which have 5 edges. This makes it a popular target for shallow-water and barotropic codes that want a uniform sphere coverage without the cubed-sphere panel seams.

Visualization

Geodesic triangular mesh, level 1
Level-1 icosahedral subdivision (80 triangles, 42 vertices). The 12 original icosahedron vertices remain visible as the only five-coordinated nodes.

Trait coverage

Registered against AbstractUnstructuredGrid. Adjacency arrays are vertices_on_face, edges_on_face, and faces_on_vertex; bulk geometry is the per-vertex Cartesian-on-sphere position and per-edge arc length.

Canonical fixtures

  • discretizations/grids/duo/icos_level0.esm — 20 faces, 12 vertices (the seed)
  • discretizations/grids/duo/icos_level1.esm — 80 faces, 42 vertices
  • discretizations/grids/duo/icos_level2.esm — 320 faces, 162 vertices

See also