Theory of acoustic scattering by supported ridges at a solid-liquid interface

Area of Science:

• Acoustics
• Solid Mechanics
• Fluid Dynamics

Background:

• Understanding acoustic wave interactions at interfaces is crucial for various applications.
• Solid inhomogeneities can significantly alter acoustic fields.
• Previous studies have explored acoustic scattering but often lack detailed analysis of pressure fields near complex geometries.

Purpose of the Study:

• To calculate first-order pressure and second-order pressure gradient fields near solid inhomogeneities at a solid/liquid interface.
• To investigate the acoustic scattering of plane waves by single and multiple ridges with trenches.
• To analyze the impact of resonant vibrational modes on acoustic fields.

Main Methods:

• Combined a general Green's function formalism with Nyborg's approach.
• Analyzed acoustic plane wave scattering by single and parallel ridges with a trench on a planar substrate.
• Calculated vibrational density of states to identify resonances.

Main Results:

• Observed low-frequency resonances, particularly in the case of a trench.
• Demonstrated that exciting trench resonant vibrational modes enhances first-order pressure and second-order pressure gradients.
• Found that trench resonant frequencies decrease and pressure enhancement increases with higher ridge aspect ratios.

Conclusions:

• Trenches on solid/liquid interfaces can support resonant vibrational modes.
• These resonant modes significantly influence acoustic pressure and gradients.
• The aspect ratio of surrounding ridges plays a key role in tuning these resonant frequencies and pressure enhancements.