Experimental testing of the variable rotated elastic parabolic equation

Area of Science:

• Ocean Acoustics
• Waveguide Propagation
• Elastic Bottom Modeling

Background:

• Shallow water acoustic propagation requires accurate modeling of transmission loss.
• Elasticity of the seafloor significantly impacts acoustic wave behavior.
• Previous experiments validated the parabolic equation method for flat/sloped elastic bottoms.

Purpose of the Study:

• To collect high-quality acoustic propagation data in shallow water waveguides with variable sloping elastic bottoms.
• To benchmark the variable rotated parabolic equation method against experimental data for complex bottom geometries.
• To investigate the effects of upslope and downslope transitions on acoustic transmission loss.

Main Methods:

• Laboratory experiments using two joined polyvinyl chloride (PVC) slabs to simulate variable bottom slopes.
• Acoustic transmissions in the 100-300 kHz frequency band.
• Data acquisition using synthetic horizontal arrays for two source positions.
• Application of the variable rotated parabolic equation method for acoustic propagation modeling.

Main Results:

• Experimental data were collected for three waveguide configurations: flat-downslope, upslope-flat, and upslope-downslope.
• The variable rotated parabolic equation method demonstrated benchmark-quality agreement with the experimental data.
• Acoustic transmission loss patterns were analyzed for varying bottom slopes and source positions.

Conclusions:

• The variable rotated parabolic equation method is effective for modeling acoustic propagation in shallow water waveguides with sloping elastic bottoms.
• Accounting for bottom elasticity and variable slopes is crucial for accurate acoustic transmission loss predictions.
• The experimental data provide valuable benchmarks for validating acoustic propagation models in complex environments.