A source term approach for generation of one-way acoustic waves in the Euler and Navier–Stokes equations

Maeda, Kazuki; Colonius, Tim

doi:10.1016/j.wavemoti.2017.08.004

Cited by 19 publications

(23 citation statements)

References 22 publications

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“…Each of the elements is designed to generate a spherical wave front that propagates inward to the center corresponding to the focal point. Further details of the transducer are available elsewhere (Maeda and Colonius, 2017). The pulse repetition frequency (PRF) is 100 Hz.…”

Section: Methodsmentioning

confidence: 99%

“…We model the transducer arrays used in the experiment as a portion of a spherical surface with an aperture of 60 mm and a radius of 50 mm with its center located at the origin. In order to generate focused ultrasound waves from the source surface, we utilize a source-term approach (Maeda and Colonius, 2017). The method can generate unidirectional acoustic waves from a surface of arbitrary geometry, in this case the spherical source surface, by forcing Eq.…”

Section: B Modeling Parametersmentioning

confidence: 99%

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Energy shielding by cavitation bubble clouds in burst wave lithotripsy

Maeda

Maxwell

Colonius

et al. 2018

The Journal of the Acoustical Society of America

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Combined laboratory experiment and numerical simulation are conducted on bubble clouds nucleated on the surface of a model kidney stone to quantify the energy shielding of the stone caused by cavitation during burst wave lithotripsy (BWL). In the experiment, the bubble clouds are visualized and bubble-scattered acoustics are measured. In the simulation, a compressible, multi-component flow solver is used to capture complex interactions among cavitation bubbles, the stone, and the burst wave. Quantitative agreement is confirmed between results of the experiment and the simulation. In the simulation, a significant shielding of incident wave energy by the bubble clouds is quantified. The magnitude of shielding can reach up to 90% of the energy of the incoming burst wave that otherwise would be transmitted into the stone, suggesting a potential loss of efficacy of stone comminution. There is a strong correlation between the magnitude of the energy shielding and the amplitude of the bubble-scattered acoustics, independent of the initial size and the void fraction of the bubble cloud within a range addressed in the simulation. This correlation could provide for realtime monitoring of cavitation activity in BWL. V

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Section: Methodsmentioning

confidence: 99%

Section: B Modeling Parametersmentioning

confidence: 99%

Energy shielding by cavitation bubble clouds in burst wave lithotripsy

Maeda

Maxwell

Colonius

et al. 2018

The Journal of the Acoustical Society of America

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“…Bubble-scattered pressure waves are resolved on the grid. The incident pressure wave is generated with a source-term approach [10].…”

Section: Numerical Setupmentioning

confidence: 99%

Numerical Simulation of the Bubble Cloud Dynamics in an Ultrasound Field

Maeda¹,

Colonius²

2018

Proceedings of the 10th International Symposium on Cavitation (CAV2018)

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We use a coupled Eulerian-Lagrangian method to simulate the dynamics of a spherical bubble cloud with various void fractions excited by high-amplitude ultrasound pulses. We consider two cases: a single cycle of a sinusoidal waveform whose wavelength is large compared to the cloud diameter, and multiple cycles with a short wavelength. For the long wavelength, bubble cloud dynamics are nearly spherically symmetric. Bubbles near the periphery grow more than the those close to the center, and the collapse of bubbles propagates inward from the periphery of the cloud. The structure and the dynamics of the cloud are scaled with the cloud interaction parameter introduce by d'Agostino and Brennen. It is shown that polydispersity does not significantly alter the cloud dynamics. In the short wavelength case, the clouds develop an anisotropic structure in the direction of the incident wave propagation. Over a wide range of the void fraction, the distal side of the cloud is shielded from the incident wave and bubbles grow less. As characterized by the center of volume of the cloud, the anisotropy is similar over the range of volume fractions considered. The results of the study can be used to characterize the acoustic cavitation in ultrasound therapies.

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“…They are highly distinct from denser and larger bubble clouds observed in SWL. For simulation of the clouds in BWL, two numerical tools are developed: a model of ultrasound generation from a medical transducer [2], and a method of simulating clouds of cavitation bubbles in the focal region [3]. For the former, an analytical expression was derived to express acoustic source distribution on an arbitrary curvature of two-dimensional surface that generates a wave propagating in a favorable direction.…”

Section: Modeling and Numerical Frameworkmentioning

confidence: 99%

Modeling and numerical simulation of the bubble cloud dynamics in an ultrasound field for burst wave lithotripsy

Maeda

Colonius

Maxwell

et al. 2018

The Journal of the Acoustical Society of America

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Modeling and numerical simulation of bubble clouds induced by intense ultrasound waves are conducted to quantify the effect of cloud cavitation on burst wave lithotripsy, a proposed non-invasive alternative to shock wave lithotripsy that uses pulses of ultrasound with an amplitude of O(1) MPa and a frequency of O(100) kHz. A unidirectional acoustic source model and an Eulerian-Lagrangian method are developed for simulation of ultrasound generation from a multi-element array transducer and cavitation bubbles, respectively. Parametric simulations of the spherical bubble cloud dynamics reveal a new scaling parameter that dictates both the structure of the bubble cloud and the amplitude of the far-field, bubble-scattered acoustics. The simulation further shows that a thin layer of bubble clouds nucleated near a kidney stone model can shield up to 90% of the incoming wave energy, indicating a potential loss of efficacy during the treatment due to cavitation. Strong correlations are identified between the far-field, bubble-scattered acoustics and the magnitude of the shielding, which could be used for ultrasound monitoring of cavitation during treatments. The simulations are validated by companion experiments in vitro. [The work was supported by NIH P01-DK043881 and K01-DK104854.]

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A source term approach for generation of one-way acoustic waves in the Euler and Navier–Stokes equations

Cited by 19 publications

References 22 publications

Energy shielding by cavitation bubble clouds in burst wave lithotripsy

Energy shielding by cavitation bubble clouds in burst wave lithotripsy

Numerical Simulation of the Bubble Cloud Dynamics in an Ultrasound Field

Modeling and numerical simulation of the bubble cloud dynamics in an ultrasound field for burst wave lithotripsy

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