A practical system for hydrodynamic optimization of ship hull forms

Since their foundation, model basins play an important role in hydrodynamic ship optimization. Their customers (ship yards, ship owners, navies, etc.) come to verify their design targets, but expect in addition advice on possible improvements. Such advice is based on experience and know-how, on careful analysis of model test results, observations in the testing facilities and, since 15 years, results of CFD calculations.
The rapid development of Computational Fluid Dynamics (CFD), i.e. the prediction of flow phenomena by numerical solution of a mathematical model of the flow, has resulted in a strongly increasing role of flow computations in hydrodynamic ship design. Analysis of the results by an experienced designer provides valuable indications on hull form modifications which are likely to improve the flow and reduce resistance. In a number of steps, significant improvements are often achieved.
Much research is now done on the possibilities to replace this process by a fully automatic optimization: to let a computer find the best ship form within the constraints set, by using suitable search techniques in combination with flow computations. However, such approaches so far have had limited success, for reasons to be explained below.
In this paper, we introduce a semi-automatic optimization technique that is more suitable for routine application in practical ship design projects. The principal innovations are:

• the completely flexible parametrisation of hull form variations;
• the effective and intuitive system for specifying the deformations;
• and the important role left for the designer, in selecting variations and analysing results.

As it will appear, this has opened the way towards a new dimension in CFD use in practical ship hull form design.