Design of Modern Ferries with Optimized Performance in a variety of sea conditions
CHALLENGE - One of the important aspects of ship design is the optimization of efficiency in both calm and rough water. This paper presents the Simulation Based Design (SBD) framework of a fast displacement ferry in terms of its wave making resistance and seakeeping performance.
SOLUTION - In this work, a custom parametric design of an existing conventional hull form was developed using CAESES. Variant hull forms were generated automatically by varying specific design variables which were selected according to their effect on the objective functions. In addition, a procedure has been produced to optimize the fitting of the parametric geometry to the parent hull form, using 3rd degree B-Spline curves. As for the calm water performance evaluation of the ship sail, the SWAN potential code solver was used, in order to estimate its wave resistance. Finally, the calm water performance of the initial and optimized hull forms were evaluated by estimating their total resistance using the Reynolds-Averaged Navier-Stokes (RANS) solver STAR CCM+. For this paper MOSA (Multi-Objective Simulation Annealing) and NSGAII (Non Dominated Genetic Algorithm II) algorithms were used, available in optimization software modeFRONTIER.
BENEFITS - A multi-objective, single stage optimization process was implemented in order to improve the hydrodynamic performance of the ferry. The reduction of the total resistance was found to be 5.74 % for Optimization 1 and 7.27 % for Optimization 2, and thus the wave resistance is slightly more reliable than wave height to be set as an objective function in calm water optimization.