Improved hexahedral mesh generation from quadrilateral surface meshes

Abstract

The quadrilateral surface mesh modification method based on dual cycle operations shows promising advantages in hexahedral mesh generation. However, as only simple cycle eliminations are considered, the existing methods can not handle complex surface meshes. In this study, an improved method based on cycle elimination is proposed for high-quality hexahedral mesh generation from a given quadrilateral mesh. For complex cycles, the dual cycles of a quadrilateral mesh are classified into different types, i.e., concave cycles, flat cycles and convex cycles, and processed accordingly. Then, a novel reversible chord removal operation is proposed to transform the concave cycles into convex cycles. Besides, the interlocked convex cycles are also split to new cycles suitable for elimination with the proposed chord removal operation. After that, the convex cycles can be eliminated. To find the best cycle for elimination, the convex cycles are ranked with geometric and topology information and the cycle with the highest rank is chosen to be eliminated. The above steps repeat until only a hexahedron exists and the final hexahedral mesh can be obtained by reversing the order of the surface modification operations. The effectiveness of the proposed method is validated with dozens of surface meshes.