NEW TECHNIQUES FOR SHIP HULL FORM OPTIMISATION BASED ON CFD
This paper discusses recently developed techniques for ship hull form optimization based on CFD computations, as are now applied in practice at MARIN. For optimising ship afterbody designs using RANS computations, multifidelity methods have been developed, aiming at a fast application to a variety of practical cases. Surrogate-based global optimisation is used, using a multi-objective genetic algorithm. The surrogates are derived by combining few high-fidelity computations, by free-surface RANS codes, with many low-fidelity computations. This paper was published in Ship Technology Research.
For rather slender vessels for which the wave resistance variations over the design space are dominant, a free-surface potential flow code is found very effective as a low-fidelity solver, permitting a large reduction of the number of RANS computations and the associated cost. Examples are shown for model 5415 and a fast displacement vessel.
For cases with variation in both viscous and wave resistance, an alternative method is used combining coarse and fine-grid RANS computations; the coarse-grid ones being about 20 times cheaper. Application of this coarse/fine grid multifidelity optimisation to a containership and a motor yacht shows its effectivity.