Efficient Strategies to Design Optimal Ship Hulls

Automatic procedures to design ship hull geometries yielding minimal wave resistance and wave breaking are an attractive opportunity from both the economical and practical standpoints. Estimating the cost function gradient according to sensitivity equation and adjoint equation methods instead of using standard finite difference approximations offers margins of cost reduction which this paper aims at assessing. A speed-up factor of about 1.6 has been obtained. The main reasons allowing the alternative methods to perform better than finite differences are the reduction of flow solutions needed to compute the cost function gradient and the possibility of using the same LU factored matrix both for the flow solver and the SEM or AM equations. Large margins of improvements exists if the computational effort spent to compute the influence coefficients of the flow solver could be reduced.