Acoustic nonlinearity parameter measurements in a pulse-echo setup with the stress-free reflection boundary

Area of Science:

• Acoustics
• Fluid Dynamics
• Nonlinear Acoustics

Background:

• Acoustic nonlinearity parameter (β) is crucial for characterizing fluid behavior.
• Existing methods for β determination can be complex and require specific setups.
• Accurate measurement of β is essential for various applications, including material science and medical imaging.

Purpose of the Study:

• To develop and validate a novel pulse-echo method for determining the acoustic nonlinearity parameter (β) in fluids.
• To derive a new formula for β that incorporates corrections for attenuation, diffraction, and boundary reflections.
• To demonstrate the method's efficacy using water as a test fluid.

Main Methods:

• Employed a pulse-echo technique utilizing a stress-free boundary condition.
• Developed a new formula for β requiring measurement of fundamental and second harmonic displacements.
• Implemented corrections for attenuation, diffraction, and boundary reflection.
• Conducted receiver calibration and harmonic generation measurements.
• Tested the method with water at varying distances from a planar transducer to a water-air interface.

Main Results:

• Successfully derived a new formula for acoustic nonlinearity parameter (β) determination.
• The pulse-echo method effectively measures fundamental and second harmonic displacements.
• Calculated β values for water showed good agreement with existing literature data.
• The method's validation was confirmed through experimental results.

Conclusions:

• The proposed pulse-echo method provides an accurate and validated approach for determining the acoustic nonlinearity parameter (β) in fluids.
• The derived formula and measurement protocol effectively account for critical wave propagation phenomena.
• This method offers a reliable tool for fluid characterization in scientific and industrial applications.