Extraction of boundary representation from surface triangulations

Many computational science tools employ nite element meshes as discretizations of the geometrical domains, and automatic mesh generation has become an indispensable part of the discretization process. Boundary representations (BRep) of solids are the means of describing the geometrical model to the mesher, thus enabling the generator to proceed without user intervention. Signi cant e ort has been devoted in the past to BRep construction in the frame-work of solid modelling systems. In this paper we consider the task of converting a tesselation (triangulation) of the surface of a solid into a BRep, and propose a robust and e cient set of algorithms for this purpose. Applications include, among others, remeshing of nite element discretizations during simulations involving not only geometric distortion but also changes in topology (coalescence and fragmentation of solids, ow, and so on).