Code = EMSHIP S2-4 (Semester 2)
Workload: lectures (20h), practical training (20h)
Number of credits: 4
The classical design process is made of three steps that are performed sequentially: hull design, hull performances evaluation, and performances analysis. Usually, this process is repeated iteratively while modifying the design until the naval architect either runs out of time or money: the design is then “optimized”. In the past years, when numerical tools were not available or not sufficiently accurate, the evaluation of the hull relied essentially on tank tests. This step is time consuming and only allows a limited number of evaluations during a fixed design period. With the improvement of numerical tolls ability to compute hull form performances, the time required to evaluate a hull has decreased to less than few hours so that in the fixed design period, an innumerable number of hulls can be evaluated. The limiting factor in the optimization chain, that was originally the evaluation of the hull, is now the time spent designing the hull and the time spent to analyze the results. The reduction in this cycle time is the main motivation for automating the full process, from the hull design to the analysis of the results and further developing an optimization tool that limits the human intervention to the selection and control of the main hull parameters which are investigated.
The optimization process is then composed of four major components: a hull modeling software that generates hull shapes, a meshing software that automatically generates the three dimensional mesh around the hull, a set of solvers for ship resistance, stability or motion in waves evaluation, and at last an optimization software (Mode-Frontier) that drives hull design parameters according to multi-objectives and constraints defined by the user.
- Presentation of existing optimisation schemes (derivative algorithms, simplex algorithm, genetic algorithms).
Industrial cases of optimisation
- Presentation of ModeFrontier, an multi-objective optimization software.
- Multi objective optimization in the naval context: cost and performance, power and seakeeping, etc.
- Practical use of Mode Frontier connected with a wave resistance software for the shape optimization of a ship with respect to resistance.
Good understanding of lectures and practical training of the previous course EMSHIP S2-3 (CFD for ship hydrodynamics) is required.
Form of exams:
Report of practical training.