Computationally efficient Prediction of Underwater Noise from Offshore Pile Driving using an equivalent line array

Over the past decade, underwater noise from pile driving for offshore wind turbine installations has raised concerns due to its impact on wildlife. Research has focused on predicting this noise, recognizing that impact loads create stress waves in steel piles. These waves reflect between the pile ends and radiate as high-pressure waves into the water due to pile expansion. Finite element analysis (FEA) has been commonly applied to model this phenomenon and has demonstrated good agreement with measurement data.This paper proposes an alternative approach to reduce the high computational costs of conventional FEA models for long ranges. The method utilizes an equivalent line array of sources along the pile, combining near-field results from FEA with Greens function from the Wavenumber Integration fast field program to calculate the source spectrum of the line array, which regenerates the noise pressure field. The alternative model's accuracy is validated against the FEA model, and parametric studies on key parameters of the equivalent source method, such as source numbers, receiver count, and coupling distance, are conducted. A recommended guideline for parameter selection is generated by highlighting their physical implications.