Voronoi cell nite di erence method for the di usion operator on arbitrary unstructured grids

Voronoi cells and the notion of natural neighbours are used to develop a nite di erence method for the di usion operator on arbitrary unstructured grids. Natural neighbours are based on the Voronoi diagram, which partitions space into closest-point regions. The Sibson and the Laplace (non-Sibsonian) interpolants which are based on natural neighbours have shown promise within a Galerkin framework for the solution of partial di erential equations. In this paper, we focus on the Laplace interpolant with a two-fold objective: rst, to unify the previous developments related to the Laplace interpolant and to indicate its ties to some well-known numerical methods; and secondly to propose a Voronoi cell nite di erence scheme for the di usion operator on arbitrary unstructured grids. A conservation law in integral form is discretized on Voronoi cells to derive a nite di erence scheme for the di usion operator on irregular grids. The proposed scheme can also be viewed as a point collocation technique. A detailed study on consistency is conducted, and the satisfaction of the discrete maximum principle (stability) is established. Owing to symmetry of the Laplace weight, a symmetric positive-de nite sti ness matrix is realized which permits the use of e cient linear solvers. On a regular (rectangular or hexagonal) grid, the di erence scheme reduces to the classical nite di erence method. Numerical examples for the Poisson equation with Dirichlet boundary conditions are presented to demonstrate the accuracy and convergence of the nite di erence scheme. Copyright ? 2003 John Wiley & Sons, Ltd.