Waveguide invariant in a gradual range- and azimuth-varying waveguide

Area of Science:

• Acoustics
• Oceanography
• Geophysics

Background:

• Sound propagation in underwater environments is complex.
• Previous studies have not reported abrupt changes in the sound propagation parameter β in sloped areas.
• Understanding sound behavior is crucial for sonar and underwater communication.

Purpose of the Study:

• To investigate and explain the previously unreported abrupt change in the sound propagation parameter β in sloped areas.
• To identify the underlying physical mechanism causing this phenomenon.
• To validate the findings through simulations.

Main Methods:

• Experimental data collection in a sloped area.
• Application of the adiabatic approximation to model sound propagation.
• Performing simulations to confirm theoretical models and experimental results.

Main Results:

• Experimental data revealed an abrupt change in β before and after a sound source reached its closest point to the hydrophone in a sloped area.
• The adiabatic approximation successfully explained this abrupt change, attributing it to azimuthal variance in the sound path.
• Simulations demonstrated perfect agreement with both the model and experimental data.

Conclusions:

• The azimuthal variance in sound paths is the cause of the abrupt change in β in sloped areas.
• The adiabatic approximation provides a valid framework for understanding this acoustic phenomenon.
• Careful consideration of β is recommended for applications involving sloped underwater environments.