Acoustic Wave Reflection in Water Affects Underwater Wireless Sensor Networks.

Area of Science:

• Acoustics
• Materials Science
• Fluid Dynamics

Background:

• Acoustic wave reflection at fluid-solid interfaces is crucial for understanding material properties.
• Poroelastic materials exhibit complex acoustic behaviors influenced by their physical characteristics.

Purpose of the Study:

• To investigate the impact of material physical qualities on oblique incidence acoustic attenuation.
• To analyze how porosity and permeability affect acoustic reflection coefficients and pseudo-Brewster angles.

Main Methods:

• Generated reflection coefficient curves by varying porosity and permeability of poroelastic solids.
• Modeled acoustic plane wave reflection and absorption on half-space and two-layer surfaces.
• Accounted for both viscous and thermal losses in the acoustic propagation.

Main Results:

• The propagation medium significantly shapes the reflection coefficient curve.
• Permeability, porosity, and frequency have less impact on the pseudo-Brewster angle and reflection minima.
• Increased porosity and permeability shift the pseudo-Brewster angle leftward, up to a limit of 73.4 degrees.

Conclusions:

• Higher porosity leads to greater angular dependence in reflection coefficient curves and reduced magnitude.
• Decreased permeability reduces the angular dependence of frequency-dependent attenuation, creating iso-porous curves.
• Matrix porosity is a key factor in the angular dependency of viscous losses within specific permeability ranges.