2023_programme: Numerical modelling of acoustic wave propagation through a bubble column

• Session: 07. Modeling techniques for underwater acoustic scattering and propagation (including 3D effects)
  Organiser(s): Boris Katsnelson and Pavel S. Petrov
• Lecture: Numerical modelling of acoustic wave propagation through a bubble column
  Paper ID: 1947
  Author(s): Smith Tom, Bempedelis Nikolaos, Grech La Rosa Andrea
  Presenter: Smith Tom
  Abstract: Modelling wave propagation through a column or screen of bubbles has a number of practical applications in underwater acoustics, including for understanding the performance of bubble curtains. These devices are used to protect marine life from high-amplitude noise sources such as pile driving, and there has recently been increased interest in using them to reduce underwater radiated noise from ship engines and propellers.\nThe transmission of an acoustic wave through a bubbly liquid depends on the nature of the incident wave, the distribution, number and size of the bubbles, and the bubble dynamics. Previous studies have shown that bubble screens are most effective at preventing high-frequency wave transmission, and that higher void fractions generally improve their performance. However many aspects, such as the influence of bubble-bubble interactions on wave transmission, are not fully understood and difficult to quantify. Capturing such phenomena using computational models is challenging but crucial to better understanding how waves travel through complex bubbly flows involving high void fractions.\nThis study uses high-fidelity computational techniques to model the transmission of an acoustic wave through a bubble column. The Euler equations are solved numerically for both the liquid and gas phases, with a Lagrangian front-tracking approach resolving the bubble-water interface. This approach removes the need for any additional modelling and allows for two-way interactions between the incident waves and bubbles to be captured. The results provide detailed insights into how acoustic waves are scattered by different bubble arrays and how the bubble dynamics affect the transmission. Relationships between the acoustic wavelength and the bubble size, void fraction, and column width are derived, providing practical guidance on how to optimise bubble screen design and develop reduced-order models for understanding their performance.
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• Corresponding author: Dr Tom Smith
  Affiliation: University College London
  Country: United Kingdom
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