COUPLING FINITE AND BOUNDARY-ELEMENT METHODS FOR 2-DIMENSIONAL POTENTIAL PROBLEMS

A finite-element-boundary-element (FE-BE) coupling method based on a w eighted residual variational method is presented for potential problem s, governed by either the Laplace or the Poisson equations. In this me thod, a portion of the domain of interest is modelled by finite elemen ts (FE) and the remainder of the region by boundary elements (BE). Bec ause the BE fundamental solutions are valid for infinite domains, a pr ocedure that limits the effect of the BE fundamental solution to a sma ll region adjacent to the FE region, called the transition region (TR) , is developed. This procedure involves a judicious choice of function s called the transition (T) functions that have unit values on the BE- TR interface and zero values on the FE-TR. interface. The present FE-B E coupling algorithm is shown to be independent of the extent of the t ransition region and the choice of the transition functions. Therefore , transition regions that extend to only one layer of elements between FE and BE regions and the use of simple linear transition functions w ork well.