Impact of Sloping Lip Wall on the Efficiency of a Duct-Type OWC Device Placed Over an Inclined Foundation

The present work investigates the optimal hydrodynamic performance of a land-fixed oscillating water column (OWC) device featurng inclined lip walls and bottom foundations. The focus is on enhancing power extraction efficiency over a wide range of frequencies. Utilizing linear water wave theory alongside boundary element method (BEM) numerical techniques, the research analyzes how key structural parameters–such as chamber width, draft ratios, and inclination angles–affect energy transfer and efficiency. The findings reveal that configurations with moderate chamber width and submergence draft ratio lead to improved performance by enhancing wave energy absorption and reducing air loss. Furthermore, a completely inclined bottom profile significantly boosts energy transfer in the short-wave range. In contrast, inclined bottom profiles with moderate draft ratios (approximately <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$b_{1}/b\approx 1.0$</tex>) and mid-range inclination angles (around <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\theta_{1}\approx 45^{\circ}$</tex>) deliver a balanced performance across a broad frequency spectrum. Moreover, fine-tuning the turbine damping parameter <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\Lambda_{\text{opt}})$</tex> is crucial for aligning with resonance frequencies, ensuring effective energy conversion. These insights are instrumental in advancing the design of OWC devices for real-world coastal and offshore applications, optimizing energy capture and conversion in various wave conditions.