Quadrilateral mesh generation on trimmed NURBS surfaces

An automatic mesh generation scheme with unstructured quadrilateral element s on trimmed NURBS surfaces has been developed. In this paper NURBS surface geometries in the IGES format have been employed to represent geometric mo dels. For unstructured mesh generation with quadrilateral elements, a domai n decomposition algorithm employing loop operators has been modified. As fo r the surface meshing, an indirect 2D approach is proposed in which both qu asi-expanded planes and projection planes are employed. Sample meshes for c omplex models are presented to demonstrate the robustness of the algorithm.