Session: 09-05-05 Wave Energy: Oscillating Water Columns

Submission Number: 180043

Numerical Study of an Oscillating Water Column With a Slotted Wall and a Horizontal Plate Using the Boundary Element Method 

Dual-purpose structures offer a promising pathway toward the commercialization of wave energy converters by enabling cost-sharing and reducing capital expenditures. One such structure combines a wave energy converter with a breakwater. Specifically, integrating a slotted breakwater with an oscillating water column (OWC) yields a modular and easily constructible OWC-breakwater design, offering potential reductions in both construction and installation costs. This configuration reduces both transmitted and reflected wave energy through two primary mechanisms: the slotted wall and the oscillating water column (OWC).  Recent experimental studies (Reyes et al., 2024) have shown that an OWC-breakwater can effectively reduce the total force exerted on the structure and the magnitude of reflected waves, while also reducing significant amounts of wave energy transmitted toward the shore by turbulence generated by the slotted structure and pneumatic power extracted by a power-takeoff device.

In this study, we investigate numerically a design modification that involves attaching a horizontal plate to the slotted wall, and evaluate its impact on key hydrodynamic parameters as well as the power extraction efficiency of the OWC. The numerical method used in this study is a boundary element method (BEM). Through BEM-based numerical simulations, the effects of the horizontal plate’s length and its distance from the bottom are examined. Results indicate that adding a horizontal plate—serving as a pseudo-bottom for the OWC—enhances energy extraction efficiency. As the plate is positioned closer to the chamber, the peak efficiency shifts toward lower frequencies. Additionally, both wave transmission and reflection decrease within the frequency range of interest. The study also examines energy losses associated with the slotted wall and evaluates the total force exerted on the structure.

* The material presented in this talk is based upon work supported by the Naval Facilities Engineering and Expeditionary Warfare Center (NAVFAC EXWC) under Contract No. N0002419D6400, Task Order No. N0002421F8805.

Reference

Reyes, C. C., Walker, M., Huang, Z., & Cross, P. (2024). A dual-function design of an oscillating water column integrated with a slotted breakwater: A wave flume study. Energies, 17(15), 3848.

Presenting Author: Clint Reyes University of Hawaii at Manoa

Presenting Author Biography: Mr. Clint Reyes is a PhD candidate in the Department of Ocean and Resources Engineering at the University of Hawai‘i at Mānoa.

Authors:

Clint Reyes University of Hawaii at Manoa
Ayrton Rodríguez National Autonomous University of Mexico
Zhenhua Huang University of Hawaii at Manoa