Numerical shape optimization of a tanker ship hull has been carried out with the aid of computational fluid dynamics (CFD) techniques and experimentally verified. The choice of a specific objective function is based on the needs of the user. In the present study, total resistance and wave pattern have been used either separately or linearly combined. In the optimization process, three different algorithms have been tested, coupled together with a CFD flow solver. A perturbation surface has been used to modify the shape of the hull, allowing for a sharp reduction of the number of design variables. Accordingly, with different objective functions and geometrical constraints, several new optimized shapes of the bulb of a tanker ship have been automatically obtained. Among them, two optimized models have been built and tested, in the INSEAN towing tank, against the original design. In both cases the measured data have confirmed the success of the optimization process.

Whereas shape optimal design has received considerable attention in many industrial contexts, the application of automatic optimization procedures to hydrodynamic ship design has not yet reached the same maturity. Nevertheless, numerical tools, combining together modern computational fluid dynamics and optimization methods, can aid in the ship design, enhancing the operational performances and reducing development and construction costs. This paper represents an attempt of applying a multidisciplinary design optimization (MDO) procedure to the enhancement of the performances of an existing ship. At the present stage the work involves modeling, development, and implementation of algorithms only for the hydrodynamic optimization. For a naval surface combatant, the David Taylor Model Basin (DTMB) model ship 5415, a three-objective functions optimization for a two-discipline design problem is devised and solved in the framework of the MDO approach. A simple decision maker is used to order the Pareto optimal solutions, and a gradient-based refinement is performed on the selected design.