Three-Dimensional Grid Generation around a Ship Hull Using the Geometrical Method

Abstract

A grid generation method called “geometrical method” was used to generate three-dimensional grid around a Series 60 (Cb =O.7) ship hull. The surface grid of the ship hull was generated by representing the hull surface using spline curves which connect the given offset points. The outer boundary was defined as a cylinder of a given radius. Intermediate points of the initial grid were given on a straight line connecting inner and outer boundary points.The initial grid was modified iteratively to satisfy four requirement criteria, i. e., orthogonality, smoothing, clustering, and minimum spacing. They were quantified based on geometrical configurations of the grid. In the procedure, the grid point locations were changed gradually to satisfy those requirements, or balance in case they conflicted. Finally, the grid was reclustered in a single sweep to be applicable to high Reynolds-number flow computation. Therefore, it is possible to generate coarse grid initially with small number of grid points and then increase the number of points in a simple manner afterwards, thus minimizing CPU time and man-hour for generating the grid.