Parametric Adjoint Optimization of a Twisted Rudder

Sammanfattning: Optimization methods are commonly used to develop new products and are also an importantstep in more incremental design improvements. In the maritime industry, these methodsare often used to create more ecient vessels and to ful ll the environmental requirementsimposed by the IMO. In recent years, the adjoint method have been used more frequently.This method can be used to predict the inuence of some input parameters on a quantityin a Computational Fluid Dynamics (CFD) simulation.In this project, the adjoint method has been investigated and applied on a relevant case;how it can be used to reduce the drag of a twisted rudder by changing the twist angles.STAR-CCM+ has been used to perform the CFD and adjoint simulations. These resultshave been imported to CAESES, a CAD-modeler, which connects the adjoint results to thedesign parameters. The adjoint results indicate a possible change of the design parameter,the twist angle is modi ed based on these results and a new geometry of the rudder is constructedin CAESES. Furthermore, the numerical results indicates that the method can beused to reduce the drag on the rudder. One of the cases in the project achieved a reductionof the rudder drag by 3.35 % and the total drag decreased with 0.18 %. However, the othertwo cases did not achieve a reduction of the drag and hence further investigations needs tobe done.The adjoint method have the possibility to be a good optimization alternative for developmentof new products or in engineering-to-order processes. The option of connecting theadjoint results to design parameters is a great advantage. On the other hand, the method inthis project is not reliable and the reason for the contradictory results needs to be studiedfurther.