Contribution
Combined CFD, 1D and FEM Modelling of Bubble Curtain Noise Attenuation Performance under the Influence of Current and Waves
* Presenting author
Abstract:
To install offshore wind turbines, piles are driven into the seabed, generating high underwater sound pressure levels. Bubble curtains (BBCs) are a common measure used to mitigate the noise. The rise of air bubbles and hence the formation of the BBC is influenced by ocean current and waves. The noise attenuation performance can be compromised if the bubble concentration decreases locally. To date, only best practice values exist for the operational parameter limits of waves and mean current. This study aims to contribute to the understanding of the influence of current and waves on BBC performance. A multi-stage simulation approach is proposed. A CFD analysis of the BBC dynamics is carried out. The CFD models the flow and BBC dynamics but cannot predict the acoustic performance of the BBC, therefore the results are subsequently used as input to a proven FEM noise propagation model. As the FEM noise propagation model uses an abstracted modelling of the BBC, the CFD results cannot be directly prescribed. An intermediate analytical processing and conversion step is required, which includes a 1D model of noise attenuation based on local BBC characteristics.