Wave-Power Extraction by an Oscillating Water Column Device over a Step Bottom

Gagan Sahoo, Harekrushna Behera () and Tai-Wen Hsu ()
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Gagan Sahoo: Center of Excellence for Ocean Engineering, National Taiwan Ocean University, Keelung 202301, Taiwan
Harekrushna Behera: Center of Excellence for Ocean Engineering, National Taiwan Ocean University, Keelung 202301, Taiwan
Tai-Wen Hsu: Center of Excellence for Ocean Engineering, National Taiwan Ocean University, Keelung 202301, Taiwan

Mathematics, 2025, vol. 13, issue 7, 1-27

Abstract: This study investigates wave-power extraction by an oscillating water column (OWC) device over a porous-to-rigid step bottom using linearized water-wave theory. The interaction between water waves and the OWC device is analyzed by solving the governing boundary-value problem with the eigenfunction expansion method (EEM) and the boundary element method (BEM). The study examines the effects of key parameters, including the porous effect parameter of the bottom, OWC chamber width, and barrier height, on the device’s efficiency. The results indicate that the porous effect parameter significantly influences OWC performance, affecting resonance characteristics and efficiency oscillations. A wider OWC chamber enhances oscillatory efficiency patterns, leading to multiple peaks of full and zero efficiency. The efficiency shifts towards lower wavenumbers with increasing step depth and barrier height but becomes independent of these parameters at higher wavenumbers. Additionally, incident angle plays a crucial role, decreasing efficiency at lower angles and exhibiting oscillatory behavior at higher angles. Furthermore, susceptance and conductance follow an oscillatory pattern concerning the gap between the porous bottom and the OWC chamber as well as chamber width. The porous effect parameter strongly modulates these oscillations. The findings provide new insights for enhancing OWC efficiency with complex bottom topography.

Keywords: oscillating water column; power extraction; step bottom; boundary element method; eigenfunction expansion method; OWC efficiency (search for similar items in EconPapers)
JEL-codes: C (search for similar items in EconPapers)
Date: 2025
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