An energy-conserving one-way coupled mode propagation model

Area of Science:

• Acoustics
• Wave Propagation
• Computational Physics

Background:

• Traditional waveguide propagation models often rely on the wave equation, leading to complex formulations with multiple coupling matrices.
• Energy conservation is a critical aspect for accurate simulation of acoustic phenomena in waveguides.
• Existing methods may struggle with range-dependent scenarios, necessitating more robust modeling techniques.

Purpose of the Study:

• To develop a novel one-way coupled mode propagation model for waveguides.
• To ensure the model conserves energy among different modes.
• To provide an efficient and accurate method for simulating acoustic propagation in range-dependent environments.

Main Methods:

• Derivation of the model from the equations of motion for pressure and displacement fields.
• Development of a single, anti-symmetric coupling matrix based on local modes and their depth derivatives.
• Application and comparison of the model with the parabolic equation (PE) method for range-dependent cases.

Main Results:

• The derived model is energy-conserving due to the anti-symmetric nature of its single coupling matrix.
• The model successfully simulates acoustic propagation in a wedge (varying water depth) and through internal waves (varying sound speed).
• Solutions obtained from the new model show good agreement with those from the established parabolic equation (PE) method.

Conclusions:

• The new coupled mode propagation model offers an energy-conserving and efficient alternative for waveguide acoustics.
• The model's foundation in equations of motion simplifies the coupling matrix formulation.
• This approach provides a valuable tool for analyzing acoustic propagation in complex, range-dependent underwater environments.