Three-dimensional Complex Geometry Surface Mesh Generation Method

In this thesis, an independent software to automatically generate unstructured grids directly on complicated 3D (3-dimensinal) surfaces has been developed using the Advancing Front Method (AFM). Visual C++, in conjunction with database technique, is used as the modeling and programming environment. Most of the geometrical data, describing 3D body features required in the software, are generated, stored and manipulated using database files and transformed into a specified format suitable for the mesh generation, and finally the AFM is employed to triangulate 3D surfaces directly.At first, the computational domain is described by the primal data of geometric parameters, which are inputted by users. The information is stored and managed with Excel data files. The API (the Application Programming Interface) attains information of models from the database system by the ODBC application of Visual C++.Another important work of the pre-process of 3D grid generation is how to describe the model exactly and unambiguously. In this paper, a new method, which can quickly and arbitrarily reshapes geometric models defined by Boolean operations, is presented. Then the information of the geometry model is transformed to a uniform data structure that can be used directly by the surface grid generation program.The generation of triangular grids on 3D surfaces for a complex geometric configuration is performed by the AFM, and the grid nodes and connectives are generated directly in 3D. This process is independent of the surface mapping, so the size and shape of the elements can be controlled more easily. Then some post-processing is applied to enhance the quality of the generated grid.Application results show that the mesh generation is robust, efficient and flexible, indicating that the proposed method and treatment are feasible and efficient for 3D surface mesh generation: The developed software enhances functions of the existing FLOW_VR environment.