Hull Form Generation And Hydrodynamic Performance Calculation Based On Form Parameters

During the preliminary design stage, to determine a ship's geometry we need efficient computational methods in the fields of geometric modeling, while to predict its hydrodynamic performance need accurate fluid dynamics stimulation. But the two are fulfill consecutively, without direct feedback. This mode of thinking makes interactive form design become the current mainstream methodology. When adopt interactive form design, designer has to modify repeatedly. It is expensive in terms of time and labor ,even dependent on worker's experience.Designers search after a fast and efficient method to determine the good form hull. Geometric modeling and hydrodynamic performance optimization must be combined to a fully integrated process. Hydrodynamic performance, such as stability, resistance, seakeeping, sea load and manoeuvre ,could be compute by the input withthe geometry. We apply a new approach——the method of parametric hull designcould generate curves and surfaces of the ship hull which shall be developed from high-level descriptors(form parameters) for their intended shapes. Building a geometric modeling system by program, the input to the modeling process is a set of parameters while the output to the calculation of hydrodynamic performance is a set of offsets. Then, the form hull has a indirect effect on hydrodynamic performance inherently. The method of parametric hull design is not only an important foundation of hydrodynamic performance optimization, but also a indispensable component.This thesis is based on advanced theory and numerical method, building a ship line generation automatic system by program, applying for ship modeling and calculation of seakeeping. There are five chapters in this thesis:In the chapter 1,it shows research background, chooses a suitable method and determines the direction of problem ,then proposes the objectivesIn the chapter 2,it introduces a hull form generation method based on form parameters in detail .First it shows the modeling process , the definition and type of form parameter. Second it should discussed how to generate a planar curve absolutely at the view of geometry——about basic curve and design section.In the chapter 3,it shows how to generate a planar curve by B-spline .Based on cubic uniform B-spline ,it proposes an new approach to model curve applying fairness criteria by mean of form parameters. It should introduce the characters of single-segment curves, multi-segment curves and special curves.In the chapter 4, it should be elaborated on how to generate a B-spline surface. To begin with, it should introduce what is skinning algorithm. In contrast with traditional skinning interpolation, a new "fairness" skinning interpolation should beintroduced——a different method by extending the proposed technique for planarcurve design to the modeling of space curves and surfaces.In the chapter 5, it could realize automation of the parametric modeling process for a high-speed vessel with transom stern. After having the offsets, it could be used for calculation of seakeeping.