Acoustic streaming around a spherical microparticle/cell under ultrasonic wave excitation
© 2015 by ASME. A microparticle/cell under an ultrasonic wave excitation generates acoustic streaming due to nonlinear interaction between the particle surface vibration and the wave excitation. For a compact spherical particle whose size is much smaller than the excitation wavelength, an analytical approach has been developed for the calculation of the streaming. However, for a particle whose size is comparable to or larger than the wavelength, existing methods require large computational resources and their results are inaccurate in the farfield of the particle. Here, a novel method is proposed to accurately and computationally efficiently calculate the streaming around particles of any sizes. In this approach, the acoustic streaming is decomposed into the compressional and shear components based on the viscous boundary layer around the particle. Accordingly, the governing equations of the acoustic streaming are then divided into homogeneous and particular ones depending on the compressional and shear streaming components, respectively. Then, each set of the equations is solved and the total solution is obtained by combining the compressional and shear acoustic streaming solutions. This method is validated by comparing its results with those obtained from the existing analytical method for compact-size particles.
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