Hydrodynamics of Flapping-Foil Wave-Assisted Propulsion Systems

A wave-assisted propulsion (WAP) system generates thrust by passive pitching and heaving of submerged hydrofoils that is induced by surface waves. Linear and/or torsional spring systems are often used to control the pitching and heaving motions that result from fluid-structure-interactions. While the thrust performance of the system is directly associated with the kinematics of the hydrofoils, the relations between the design and kinematic parameters are not well understood, and this creates a challenge for control and optimization of the WAP system. In the present study, the hydrodynamics and associated thrust performance of WAP systems is investigated by high-fidelity computational flow models and data-enabled analysis tools. By analysing the simulation results, a new scaling parameter for predicting thrust performance is derived and verified. A control strategy based on this new parameter to optimize the thrust performance of WAP system is also explored for monochromatic as well as stochastic surface wave conditions.