An integrated optimization design of a fishing ship hullform at different speeds

The purpose of this paper is to show how the improvement of the hydrodynamics performance of a ship can be achieved by solving a shape optimization design problem at different speeds using the Simulation-Based Design (SBD) technique. The SBD technique has been realized by integrating advanced CFD codes, global optimization algorithms and geometry modification methods, which offers a new way for hullform optimization design and configuration innovation. Multiple speeds integrated optimization has been a challenge for hullform design. In this paper, an example of the technique application for a fishing ship hullform optimization at different speeds is demonstrated. In this process, Free-form Deformation method is applied to automatically modify the geometry of ship, and the Multi-Objective Particle Swarm Optimization (MOPSO) algorithm is adopted for exploring the design space. Two objective functions, the total resistances at two different speeds (12kn and 14kn) are assessed by RANS solvers. The optimization results show that the decrease of total resistance is significant for the optimization case at the two speeds, with a reduction of 5.0% and 11.2% respectively. Finally, dedicated experimental campaigns for the design model and the optimized model are carried out to validate the computations and the optimization processes. At the two speeds, the reduction of the total resistance in model scale is about 6.0% and 11.8% for the optimized case. These are a valuable result considering the small modifications allowed and the good initial performances of the original model. The given practical example demonstrates the feasibility and superiority of the proposed SBD technique for multiple speeds integrated optimization problem.