Matthieu Abgrall, Paolo Perali, Matthieu Sacher, Benoı̂t Clément, Romain Lécuyer-Le-Bris
Abstract This work proposes a surrogate-based framework to simultaneously optimize the geometry and kinematics of a three-dimensional oscillating foil operating near the free surface. The study targets a compromise between mean thrust and hydrodynamic efficiency, exploring Pareto-optimal solutions using the Boundary Element Method solver PUFFIn and an Efficient Global Optimization strategy. Both sinusoidal and non-sinusoidal motion laws are considered, with non-sinusoidal trajectories yielding improved performance at low Strouhal numbers. Geometric parameters, including span and chord distribution, are optimized alongside kinematics, while sweep and dihedral are found to have a limited influence on overall performance. Selected optimal designs are further assessed with Reynolds-Averaged Navier-Stokes simulations. Keywords whale-inspired oscillating foil; auxiliary ship propulsion; multi-objective optimization; efficient global optimization; boundary element method; Reynolds-averaged Navier-Stokes