Sound propagation over layered poro-elastic ground using a finite-difference model

Area of Science:

• Geophysics
• Acoustics
• Computational Mechanics

Background:

• Sound propagation over ground involves complex interactions between atmospheric and seismic waves.
• Accurate modeling is crucial for understanding phenomena like airblast effects and seismic wave generation.

Purpose of the Study:

• To develop and validate a novel axisymmetric pressure-velocity finite-difference (PV-FD) formulation for modeling sound propagation in a homogeneous atmosphere over layered poro-elastic ground.
• To simulate and analyze the coupled atmosphere-ground system response during airblast events.

Main Methods:

• Implementation of Biot's poro-elastic theory into an axisymmetric pressure-velocity finite-difference (PV-FD) formulation.
• Coding the formulation into a computer program for simulations.
• Validation against experimental airblast test measurements and comparison with frequency-wave number FFP simulations.

Main Results:

• The PV-FD model successfully simulates synthetic time histories of atmospheric overpressure and ground vibration.
• Snapshot plots reveal the dynamic response of the atmosphere-ground system.
• Demonstration of Mach surface generation in ground motion when sound speed exceeds Rayleigh wave velocity.

Conclusions:

• The proposed PV-FD model provides a sound and validated approach for simulating sound propagation and coupled atmosphere-ground dynamics.
• The model accurately captures key physical phenomena, including Mach surface generation, relevant to airblast events.