Related Experiment Video
Updated: May 24, 2026

Microparticle Manipulation by Standing Surface Acoustic Waves with Dual-frequency Excitations
Published on: August 21, 2018
Forces acting on a small particle in an acoustical field in a viscous fluid
1Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech Building 345 B, DK-2800 Kongens Lyngby, Denmark.
Abstract:
We calculate the acoustic radiation force from an ultrasound wave on a compressible, spherical particle suspended in a viscous fluid. Using Prandtl-Schlichting boundary-layer theory, we include the kinematic viscosity of the solvent and derive an analytical expression for the resulting radiation force, which is valid for any particle radius and boundary-layer thickness provided that both of these length scales are much smaller than the wavelength of the ultrasound wave (millimeters in water at megahertz frequencies). The acoustophoretic response of suspended microparticles is predicted and analyzed using parameter values typically employed in microchannel acoustophoresis.
More Related Videos
10:14Fabrication and Operation of Acoustofluidic Devices Supporting Bulk Acoustic Standing Waves for Sheathless Focusing of Particles
Published on: March 6, 2016
11:32A Microfluidic Platform for Precision Small-volume Sample Processing and Its Use to Size Separate Biological Particles with an Acoustic Microdevice
Published on: November 23, 2015
Related Concept Videos
Stokes' Law
The expression for the force on a solid spherical object in a fluid is called Stokes' law. Stokes' law is valid only for low Reynolds...
Deriving the Speed of Sound in a Liquid
The speed of sound in fluids can be derived by considering a mechanical wave propagating...
Sound as Pressure Waves
The pressure fluctuation depends on the difference in displacements between the successive points in the...
Intensity and Pressure of Sound Waves
Unlike the time average of a sinusoidal term, which is zero since it is positive and...
Sound Waves
Sound waves are longitudinal in most fluids because fluids cannot sustain any lateral pressure. In solids, however, shear forces help in propagating the disturbance in the lateral direction as well. Hence,...
Speed of Sound in Solids and Liquids