A continuum description of unstructured meshes in two dimensions, both for planar and curved surface domains, is proposed. The meshes described are those which, in the limit of an increasingly finer mesh (smaller cells), and away from irregular vertices, have ideally-shaped cells (squares or equilateral triangles), and can therefore be completely described by two local properties: local cell size and local edge directions. The connection between the two properties is derived by defining a Riemannian manifold whose geodesics trace the edges of the mesh. A function φ, proportional to the logarithm of the cell size, is shown to obey the Poisson equation, with localized charges corresponding to irregular vertices. The problem of finding a suitable manifold for a given domain is thus shown to exactly reduce to an Inverse Poisson problem on φ, of finding a distribution of localized charges adhering to the conditions derived for boundary alignment. Possible applications to mesh generation are discussed.Key words: Unstructured mesh generation, differential geometry.
PACS:1 Overview A mesh is a partition of a domain into smaller parts, typically with simpler geometry, called cells. In two dimensions, both on the plane and on curved surfaces, cells are usually triangles or quadrilaterals. The shapes of the cells may be important; for many applications, cells with shapes similar to an equilateral triangle or a square are preferred. The problem of mesh generation can then be seen as an optimization problem: to find a partition of a domain into well-shaped cells, possibly under additional demands, such as cell size requirements.