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Sound scattering by bubble clouds near the sea surface
1Naval Surface Warfare Center, Carderock Division, W. Bethesda, Maryland 20817-5700, USA.
The Journal of the Acoustical Society of America
|January 21, 2000
Summary
The scattering cross-section of air bubble clouds near a free surface is calculated using a novel method. This accounts for multiple scattering and boundary effects, offering new insights into acoustic wave interactions in the ocean.
Area of Science:
- Acoustics
- Fluid Dynamics
- Wave Scattering
Background:
- Classical acoustic scattering theory for single bubbles.
- Generalization to multiple interacting bubbles in a cloud.
- The impact of a free surface on acoustic scattering.
Purpose of the Study:
- To develop a generalized formulation for the scattering cross-section (SCS) of bubble clouds near a free surface.
- To account for multiple scattering orders and boundary effects.
- To provide a method for evaluating the form function of bubble clouds.
Main Methods:
- Generalization of classical exact formulation for single bubbles.
- Application of the method of images and addition theorem for spherical wave functions.
- Solving an infinite set of coupled algebraic equations for coupling coefficients using Wigner 3-j symbols.
Main Results:
- A modified SCS formulation for bubble clouds near a free surface.
- Numerical results for four geographical sites with varying bubble concentrations.
- Comparison of results with and without boundary effects.
Conclusions:
- The presence of a free surface significantly alters the SCS of bubble clouds.
- The developed method accurately accounts for multiple scattering and boundary interactions.
- The findings are relevant for understanding acoustic propagation in marine environments with bubble layers.