RIASSUNTO
Abstract
The paper discusses the application of the homotopy algorithm, coupled with a hull form modification method based on RBF(Radial basis function)interpolation, in order to deal with the inverse design of the fore part of the ship hull of a modern container ship KCS. The RBF interpolation has been use to allow the modifications of the ship forebody. The optimized hull form for minimizing the wave-making coefficient have been obtained, and hence analyzed and compared to the basis hull form in order to demonstrate the effectiveness of the developed procedure.
Introduction
In the recent few decades, important breakthrough has been made in practical application of CFD to ship hydrodynamics. Today, the rapid development of CFD technology provides an accurate and reliable tool to the ship hydrodynamic performance evaluation and prediction, and the rapid development of SBD(Simulation Based Design) optimization technique provides a scientific method to solve ship hull form design problems.
The applications of SBD technique to hydrodynamic optimization (mostly for reducing calm water resistance and wave patterns) have been reported in a significant number of studies (Day and Doctors 2000; Kim and Chun, 2008; Campana et al., 2004; Yang, 2011). In this article, the focus is on breaking through key technologies such as optimization algorithms, hull geometry modification and reconstruction, and code integration.
There are two kinds of methods to solve the optimization problem. One is the so-called heuristic algorithms and the other is the conventional gradient-based algorithms. The former, such as Genetic Algorithm (Dejhalla et al., 2002; Bagheri and Ghassemi, 2014), in which the initial solution do not need to be carefully selected and the global solution can be obtained. However, these methods are very timeconsuming because they have to establish the "populations" and thus a large number of CFD processes must be done. In contrast, the gradient based algorithms, such as the Levenberg-marquardt method (Huang et al., 1998;Chen and Huang, 2002; Chen and Huang, 2004; Chen et al., 2006) are more effective than the heuristic algorithms because they are "one-solution based" algorithms in which the number of CFD prosesses are much fewer. In this work, another gradient-based algorithm called homotopy algorithm has been applied in the optimization process.