Grid Generation on NURBS Surfaces Developed for Ship Hull Form Optimization

A grid generation tool is developed for the hydrodynamic optimization of ship hull forms. The tool includes three components: the preprocessor that consists of the I/O interfaces with IGES/3DM files, the module for ship hull form manipulations and the boundary interpreter; the triangular mesh generator that utilizes the advancing front method and the point projection technique; and the post-processor that handles mesh quality improvements and code performance statistics. An example of a singularity caused by poor parameterizations is discussed and a modified projection matrix is proposed to avoid singularities. The use of a designed octree structure improves the runtime efficiency of the code. The detailed implementations are discussed in this paper. This tool is tested on three representative ship models and the results show that it can be used for CFD-based flow predictions and ship hull form optimizations.