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Acoustic transmission across a roughened fluid-fluid interface
R Lim1, I C Paustian, J L Lopes
1Coastal Systems Station, Panama City, Florida 32407-7001, USA.
The Journal of the Acoustical Society of America
|April 28, 2001
Summary
Tank experiments revealed that roughened fluid interfaces scatter significant acoustic energy. Discrepancies between observed scattering and Bragg predictions were attributed to near-field effects and ignored scattering directionality.
Area of Science:
- Acoustics
- Fluid Dynamics
- Materials Science
Background:
- Anomalous acoustic transmission through fluid interfaces is observed in field experiments.
- Heuristic Bragg scattering predictions are used to explain these observations.
- Simulating interface roughness is key to understanding acoustic behavior.
Purpose of the Study:
- Investigate acoustic transmission across roughened fluid-fluid interfaces.
- Test heuristic Bragg scattering predictions.
- Identify reasons for discrepancies between predictions and experimental observations.
Main Methods:
- Tank experiments using immiscible fluids (vegetable oil/glycerin).
- Simulated interface roughness with polystyrene beads of varying diameters.
- Acoustic measurements using a hydrophone array and beamforming in the 100-200 kHz range.
- Comparison of experimental data with computer simulations.
Main Results:
- Significant acoustic energy scattering into the bottom fluid layer by interface beads.
- Scattered acoustic levels increased with increasing bead diameter.
- Discrepancies observed between measured propagation properties and Bragg scattering predictions.
Conclusions:
- Near-field reception effects and ignored scattering directionality explain discrepancies with Bragg predictions.
- Findings have implications for interpreting acoustic observations in field experiments.
- Understanding interface scattering is crucial for accurate acoustic modeling.