Abstract
This study examines the design and performance of a seafloor-mounted, subsurface pressure differential (PD) wave energy converter (WEC) that utilizes a single deformable, water-filled chamber to harness energy from passing ocean waves. This configuration is designed for low-power underwater applications, such as sensors, remotely operated vehicles, and gliders, where long-term deployment and a compact design are essential. The deployment constraints require a small-scale form factor (within the footprint of roughly 1 m^2) with a power output of 1-100 W and the capacity to operate autonomously in remote locations. The device operates through the cyclic compression and expansion of the chamber, driven by wave-induced pressure variations. This process drives fluid through a turbine into an accumulator, reversing the flow as the reduced pressure from the wave trough reaches the accumulator. A numerical model is developed to characterize the system, utilizing hydrodynamic coefficients calculated via NEMOH, an open-source boundary element solver. These coefficients inform a MATLAB numerical model that computes response amplitude operators and estimates power output. The modeling framework is applied to examine the influence of chamber geometry and volume on device efficiency by simulating various deformable chamber shapes. The predicted power production is then evaluated under idealized sea state conditions. A bench-scale physical model is constructed to validate the numerical model through physical testing. Observed discrepancies between numerical and experimental results highlight the need for improved characterization of the pressure-to-flow conversion mechanism and the mechanical behavior of the deformable structure. Finally, the results are scaled and applied to estimate the size required to meet deployment application performance targets. The study provides foundational insights into the feasibility and scaling behavior of PD WECs, supporting the future development of submerged energy harvesting systems for small-scale applications.