Related Experiment Video
Updated: Jul 16, 2026
08:19
Induction of Microstreaming by Nonspherical Bubble Oscillations in an Acoustic Levitation System
Published on: May 9, 2021
Acoustic localization in weakly compressible elastic media containing random air bubbles
1Laboratory of Modern Acoustics and Institute of Acoustics, Nanjing University, Nanjing 210093, People's Republic of China.
Summary
Acoustic localization occurs in bubbly elastic media, trapping waves near the source. This phenomenon is identified using spatial wave field correlations, even with minimal bubble presence.
Area of Science:
- Acoustics
- Materials Science
- Wave Propagation
Background:
- Weakly compressible elastic media with random air bubbles present unique wave propagation challenges.
- Understanding wave behavior in such complex media is crucial for various engineering applications.
Purpose of the Study:
- To theoretically investigate longitudinal wave propagation in bubbly elastic media.
- To identify and analyze acoustic localization phenomena in these media.
- To develop and validate a method for detecting acoustic localization.
Main Methods:
- Utilized a self-consistent method to model wave propagation.
- Analyzed scattering cross-section and mean free paths of elastic waves.
- Incorporated multiple scattering effects using bubble dynamic equations.
- Employed spatial correlation analysis of the wave field to detect localization.
Main Results:
- Mode conversion during wave scattering by bubbles was found to be negligible.
- Acoustic localization was theoretically identified at frequencies above bubble resonance, even with low bubble volume fractions.
- The developed spatial correlation method effectively identified acoustic localization.
- Localization features were found to be sensitive to medium structure parameters.
- Acoustic energy was observed to be trapped near the source during localization.
Conclusions:
- Acoustic localization is a significant phenomenon in bubbly elastic media.
- The spatial correlation method provides an effective means to detect and study acoustic localization.
- The findings offer insights into wave energy trapping and control in complex materials.
More Related Videos
Related Concept Videos
00:51Speed of Sound in Solids and Liquids
Most solids and liquids are incompressible—their densities remain constant throughout. In the presence of an external force, the molecules tend to restore to their original positions, which is only possible because the constituents interact. The interactions help the constituents pass on information about external disturbances, like sound waves. Therefore, sound waves travel faster through these media. Compared to solids, the constituents in a liquid are less tightly bound. Thus, sound waves...
01:17Sound as Pressure Waves
Sound waves, which are longitudinal waves, can be modeled as the displacement amplitude varying as a function of the spatial and temporal coordinates. As a column of the medium is displaced, its successive columns are also displaced. As the successive displacements differ relatively, a pressure difference with the surrounding pressure is created. The gauge pressure varies across the medium.
The pressure fluctuation depends on the difference in displacements between the successive points in the...
The pressure fluctuation depends on the difference in displacements between the successive points in the...
01:09Deriving the Speed of Sound in a Liquid
As with waves on a string, the speed of sound or a mechanical wave in a fluid depends on the fluid's elastic modulus and inertia. The two relevant physical quantities are the bulk modulus and the density of the material. Indeed, it turns out that the relationship between speed and the bulk modulus and density in fluids is the same as that between the speed and the Young's modulus and density in solids.
The speed of sound in fluids can be derived by considering a mechanical wave propagating...
The speed of sound in fluids can be derived by considering a mechanical wave propagating...
01:28Standing Waves in a Cavity
A household microwave and lasers are examples of standing electromagnetic waves in a cavity. When two conducting metal plates are placed parallel at the nodal planes, it creates a cavity where standing waves are formed. The cavity between the two planes is analogous to a stretched string held at the points x = 0 and x = L. Here, the distance 'L' between the two planes must be an integer multiple of half of the wavelength. The wavelengths that satisfy this condition are given by:
01:22Elastic Strain Energy for Normal Stresses
Strain energy quantifies the energy stored within a material due to deformation under loading conditions, a fundamental concept in materials science and engineering. The strain energy can be modeled when a material is subjected to axial loading with uniformly distributed stress. In this scenario, the stress experienced by the material is the internal force divided by the cross-sectional area, and the strain induced is directly proportional to this stress through the modulus of elasticity.
If...
If...
01:06Echo
The human ear cannot distinguish between two sources of sound if they happen to reach within a specific time interval, typically 0.1 seconds apart. More than this, and they are perceived as separate sources.
Imagine the sound is reflected back to the ears. Assuming that the source is very close to the human, the difference between hearing the two sounds—the emitted sound and the reflected sound—may be more than the minimum time for perceiving distinct sounds. If this is the case, then the...
Imagine the sound is reflected back to the ears. Assuming that the source is very close to the human, the difference between hearing the two sounds—the emitted sound and the reflected sound—may be more than the minimum time for perceiving distinct sounds. If this is the case, then the...