Global Optimization and Variable Fidelity Strategies in the Single and Multiobjective Optimal Design of Fast Multihull Ships

The fundamental elements and strategies needed to build and apply SBD are discussed, with attention to some critical issues, such as global optimization algorithms, grid deforming techniques, parallel architectures and large number of design variables. In the attempt to include also tools more familiar to the vast majority of ship designers, a new approach using the variable fidelity concept is presented in the variable- physics version and adapted for derivative-free methods, allowing for an integration of accurate RANS predictions together with fast potential flow results. The numerical optimization of a fast catamaran is the application presented in this paper, which follows preliminary results presented in Campana et al. (2006-a). The shape optimization is carried out via two different Simulation-Based Design (SBD) frameworks, developed has the result of a close collaboration between code developers, users and industry. Attention was devoted into the precise definition and implementation of real industrial constraints.