Reliability-based robust design optimization for ships in real ocean environment

A reliability-based robust design optimization for resistance reduction and operability increase in head waves from a real ocean environment is formulated and solved. The analysis tool consists in a URANS solver coupled with uncertainty quantification methods for variable regular wave, based on a Monte Carlo simulation with metamodels. The design optimization methods include the Karhunen-Loe?ve expansion of the geometry modification space, coupled with design of experiments and metamodels, and a multi-objective particle swarm optimization algorithm. To reduce the computational effort, a simplified model is introduced for the effects of sea state and speed on the subsystem's seakeeping responses. The application presented is a 100m Delft catamaran sailing in the North Pacific Ocean, with speed in the range Fr = 0.115 ÷ 0.575. An optimal design is selected, providing a 2.8% reduction for the expected value of the mean resistance and an 8.5% increase in operability, based on stochastic operations.