Wave-driven propulsion of a flexible raft

Wave-driven propulsion at fluid interfaces arises when floating bodies subjected to oscillatory forcing generate and interact with surface waves, resulting in net drift and propulsion. Previous efforts have studied this form of interfacial locomotion both experimentally and theoretically, but existing modeling efforts have been limited to rigid bodies. In this work, we model the response of a driven flexible raft using an Euler–Bernoulli beam equation that is coupled to a quasi-potential free surface model for the fluid motion. This coupled fluid–structure model incorporates the raft's stiffness as a new parameter, allowing for the exploration of resonant phenomena and their influence on propulsion. This computationally efficient reduced-order modeling framework is suitable for Bayesian and gradient-based optimization, enabling the systematic exploration of a broad design space that includes structural stiffness, mass distribution, forcing strength and distribution, raft length, and driving frequency. This modeling framework and its predictions will inform future computational and experimental work on flexible wave-driven propulsion.