Object Functions for Optimizing a Ship’s Aft Body

The choice of object functions is of crucial importance in hull form optimization projects. In this paper we consider two object functions, the first is an estimate of the required power to sustain a given speed, and as a second we consider some choices of a function that expresses the wake quality. Their behavior is studied in a five-dimensional design space constructed for multi-objective optimization of the aft body of a chemical tanker using a RANS code. The choice of the force distribution representing the propeller can have a non-negligible effect on powering parameters such as the thrust deduction fraction.