Next Article in Journal
The Acoustics of the Choir in Spanish Cathedrals
Next Article in Special Issue
The 3D Spatial Autocorrelation of the Branching Fractal Vasculature
Previous Article in Journal
Acoustic Simulation of Julius Caesar’s Battlefield Speeches
Open AccessArticle

Effects of Nonlinear Propagation of Focused Ultrasound on the Stable Cavitation of a Single Bubble

Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
*
Author to whom correspondence should be addressed.
Acoustics 2019, 1(1), 14-34; https://doi.org/10.3390/acoustics1010003
Received: 18 October 2018 / Revised: 21 November 2018 / Accepted: 3 December 2018 / Published: 6 December 2018
(This article belongs to the Special Issue Acoustics in Biomedical Engineering)
Many biomedical applications such as ultrasonic targeted drug delivery, gene therapy, and molecular imaging entail the problems of manipulating microbubbles by means of a high-intensity focused ultrasound (HIFU) pressure field; namely stable cavitation. In high-intensity acoustic field, bubbles demonstrate translational instability, the well-known erratic dancing motion, which is caused by shape oscillations of the bubbles that are excited by their volume oscillations. The literature of bubble dynamics in the HIFU field is mainly centered on experiments, lacking a systematic study to determine the threshold for shape oscillations and translational motion. In this work, we extend the existing multiphysics mathematical modeling platform on bubble dynamics for taking account of (1) the liquid compressibility which allows us to apply a high-intensity acoustic field; (2) the mutual interactions of volume pulsation, shape modes, and translational motion; as well as (3) the effects of nonlinearity, diffraction, and absorption of HIFU to incorporate the acoustic nonlinearity due to wave kinematics or medium—all in one model. The effects of acoustic nonlinearity on the radial pulsations, axisymmetric modes of shape oscillations, and translational motion of a bubble, subjected to resonance and off-resonance excitation and various acoustic pressure, are examined. The results reveal the importance of considering all the involved harmonics and wave distortion in the bubble dynamics, to accurately predict the oscillations, translational trajectories, and the threshold for inertial (unstable) cavitation. This result is of interest for understanding the bubble dynamical behaviors observed experimentally in the HIFU field. View Full-Text
Keywords: focused ultrasound; nonlinear acoustics; stable cavitation; ultrasound microbubble dynamics focused ultrasound; nonlinear acoustics; stable cavitation; ultrasound microbubble dynamics
Show Figures

Figure 1

MDPI and ACS Style

Bakhtiari-Nejad, M.; Shahab, S. Effects of Nonlinear Propagation of Focused Ultrasound on the Stable Cavitation of a Single Bubble. Acoustics 2019, 1, 14-34.

Show more citation formats Show less citations formats

Article Access Map by Country/Region

1
Back to TopTop