Shape Optimization Design of a Heaving Buoy of Wave Energy Converter Based on Fully Parametric Modeling and CFD Method

Abstract

Hydrodynamic shape of the heaving buoy is an important factor of the motion response in waves and thus energy conversion efficiency for point absorbers (PAs). Experience-based design considerations are currently limited by design ideas and time consumptions, hence the need for faster and smarter methods. An automated optimization method based on a fully parametric modeling method and Computational Fluid Dynamics (CFD), is proposed in the present paper. Using this method, a benchmark buoy is screen designed and then optimized for maximizing heave motion response. The geometry is described parametrically and deformed by means of the free-form deformation (FFD) method. During the optimization process, the expansion factor of control points is the basis for variations. A combination of Sobol and non-dominated sorting genetic algorithm II (NSGA-II) is used to search for the solutions. After several iterations, the heaving buoy shape with optimal heave motion response is obtained. The analyses show that the heave motion response has increased 55.3% after optimization. The developed methodology is valid and seems to be a promising way to design a novel buoy that can significantly improve the wave energy conversion efficiency of PAs in future works.