Spectral Analysis of Irregular Sea Waves

Abstract

Accurate modeling of ocean wave behavior is a critical component in ensuring the safety, efficiency, and longevity of offshore structures and naval systems. The marine environment is inherently complex, characterized by highly irregular and dynamic wave patterns influenced by a wide range of environmental factors, including wind, tides, and ocean currents. These variables introduce significant challenges in predicting wave-induced forces and their impact on floating and fixed offshore platforms, vessels, and energy harvesting devices. To address these challenges, spectral wave analysis has emerged as a fundamental approach, offering engineers a robust framework for interpreting and simulating wave behavior with enhanced precision. Among the numerical techniques employed in spectral analysis, the Fast Fourier Transform (FFT) stands out due to its computational efficiency and ability to decompose complex, time-domain wave signals into their constituent frequency components. This transformation enables a clearer understanding of the temporal and spatial characteristics of wave motion, which is essential for the design of resilient and adaptive offshore systems. In this context, the present study investigates the application of Fourier series and FFT in modeling irregular sea wave patterns, emphasizing their effectiveness in representing periodic and quasi-periodic phenomena through the superposition of sinusoidal functions. The methodology of this study involves the acquisition of real-world wave data from the Rede Ondas project, followed by signal processing using FFT implemented in spreadsheet software. The resulting complex coefficients were analyzed to extract amplitude and frequency information, enabling the construction of a spectral profile of the wave field. Key wave parameters such as significant wave height and peak frequency were identified, providing insights into the dynamic loading conditions that offshore structures may encounter.