Analytical gradients of first-order diffraction and radiation forces for design optimization of floating structures

Abstract

Gradient-based design optimization of floating structures with many design variables requires efficient and accurate computation of hydrodynamic coefficients including wave excitation forces and their derivatives with respect to design variables. For large-volume structures or structures with many component members, the only practical method to determine diffraction and radiation forces is to apply a boundary element method solver. This work presents the first known boundary element method solver with implicit analytic derivatives, allowing for total derivative computation alongside force evaluation. Two case studies are presented: a single floating circular column and a structure with multiple square columns attached to a horizontal pontoon. Force results from both case studies agree well with reference data, while derivative results agree with the best comparisons available. Computational requirements limit the applicability of this method and suggest further work is required to refine this approach.