A finite element technique for solving 2-D open boundary problems

A finite element recursion technique is described for the solution of open-boundary electric and magnetic field problems. The method is to model the exterior region by an annular "super-element" in which all the nodes except those on the inside edge have been eliminated. The routine to generate the annulus and its element division automatically is detailed. This algorithm calculates the boundary coefficients representing the exterior Laplacian region from a knowledge of the interior region boundary node distribution. The method has been tested by comparing calculated solutions with results obtained from both analytical and experimental models and good agreement achieved.