Study of Diameter-to-Draft Ratio of Pitch Point Absorber as Wave Energy Converter in Indonesia Waters Based on Boundary Element Method

Abstract

Recently, harnessing the energy from low wave energy density areas is concerned to deal with renewable energy targets. The previous study proposed a pitch point absorber with a submerged sectional equivalent area as the design parameter. However, that parameter did not suggest the best sectional area and did not directly correlate with the theory of structure hydrodynamic. Thus, this research proposes the diameter-to-draft ratio as a design parameter for the pitch point absorber. The study was conducted numerically using Boundary Element Method software to investigate diffraction characteristics of the device and analyze structure response in irregular waves. The model was modified with five different diameters and ratios. JONSWAP Spectrum was used to generate wave elevation with a 2-m significant wave height and 10-second peak period. The time domain simulation was set at 10.800 seconds. The result of this study showed that the highest responses occurred when the diameter-to-draft ratio was 5 because it has the closest structure natural frequency to assumed wave frequency, which makes it easier to resonate. In all diameters, the higher ratio affects the range of the structure natural frequency getting farther from the assumed wave, so the responses become smaller.