Quadrilateral surface mesh generation with improved quality by combination of triangles (Q6589345)

The paper deals with the generation of quadrilateral meshes in 2D and 3D cases. The authors propose an enhanced indirect method by the combination of triangles. It takes a triangular mesh as the input, and except that the number of elements needs to be even, the triangular mesh can be generated by the commonly used AFT method or Delaunay method. To ensure the quality of the combined quads, a local-global triangular remeshing procedure is conducted first, and size gradation and vertex valence are focused in this step. Then, the well-known Blossom algorithm is used to find the perfect matching triangles for combination. Finally, in order to reduce the number of unnecessary singularities, a connectivity optimization procedure is introduced to replace the irregular elements in local regions with regular elements and thus improve the overall quality of the combined quads. The performance of the proposed method is demonstrated by several 2D and 3D complex numerical experiments including airplane F16 and tower-bridge models.