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Related Experiment Video

Updated: Apr 18, 2026

Fabrication and Operation of Acoustofluidic Devices Supporting Bulk Acoustic Standing Waves for Sheathless Focusing of Particles

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Acoustic interaction forces between small particles in an ideal fluid.

Glauber T Silva¹, Henrik Bruus²

¹Physical Acoustics Group, Instituto de Física, Universidade Federal de Alagoas, Maceió, Alagoas 57072-970, Brazil.

Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics

|January 24, 2015

Summary

We developed a theory for acoustic interaction forces between small particles in fluids. Particles aggregate along wave direction, with attraction or repulsion in the transverse direction.

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Microparticle Manipulation by Standing Surface Acoustic Waves with Dual-frequency Excitations

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Published on: August 21, 2018

Area of Science:

Acoustics
Fluid Dynamics
Particle Physics

Background:

Acoustic radiation force influences particle behavior in fluids.
Understanding inter-particle forces is crucial for controlling suspensions.

Purpose of the Study:

To derive a theoretical expression for acoustic interaction force between small particles.
To investigate particle aggregation and interaction in acoustic fields.

Main Methods:

Developed a theoretical model for acoustic interaction force in the Rayleigh limit.
Applied the theory to particle suspensions in standing and traveling plane waves.
Utilized a mean-field approximation for emulsions.

Main Results:

Acoustic interaction forces are approximated by gradients of pair-interaction potentials.
Particles aggregate along the wave propagation direction.
Transverse interactions can be attractive or repulsive.

Conclusions:

The theoretical framework accurately describes acoustic interaction forces.
Predicts particle aggregation patterns in response to acoustic waves.
Provides a method for analyzing acoustic forces in emulsions.