Numerical study of the kinematic and acoustic characteristics of bubble clusters

Deng, Fuqiang; Zhao, Di; Zhang, Lingxin; Shao, Xueming

doi:10.1007/s42241-023-0007-1

Cited by 10 publications

(4 citation statements)

References 31 publications

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“…From our previous studies [25] , we found that the bubble clusters collapse sequentially from the outer layers towards the core, with each layer's collapse emitting sound pressure. The end of bubble's collapse coincides with the emission of the highest sound pressure, creating a peak sound pressure value.…”

Section: Collapse Of Bubble Clustersmentioning

confidence: 76%

“…[28] To ensure clarity and simplicity, our method includes a constant pressure constraint within the bubble, a model extensively utilized in our previous research. [25,29] The Tait equation of state is used to effectively simulate the liquid phase's compressibility under the high pressures caused by bubble collapse, as well as to model the propagation of large amplitude sound waves in the liquid. [30] 𝑝…”

Section: Numerical Methods For Vapor Bubblesmentioning

confidence: 99%

“…In this work, we use the Farassat 1A [35] integral solution of the FW-H equation for penetrable surfaces to solve for the far-field noise, and a specific expression for this integral solution can be found in our previous literature. [25] 2. Configurations for simulation Figure 1 illustrates the arrangement method of a bubble cluster containing 352 vapor bubbles，where the initial radius of each bubble in the bubble cluster is 𝑅 0 = 2 mm.…”

Section: Acoustic Analogymentioning

confidence: 99%

“…In our previous study [25] , direct numerical simulations of the collapse of dense bubble clusters containing 13-352 vapor bubbles with volume fractions ranging from 17% to 40.7% were performed and the far-field noise radiated by the bubble clusters was predicted using the FW-H method. The results show that the sound pressure levels(SPL) of the bubble clusters decay with increasing frequency, which varies linearly with the octave.…”

Section: Introductionmentioning

confidence: 99%

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Numerical study of the acoustic spectrum of bubble clusters

Deng,

Zhao,

Zhang

et al. 2024

Preprint

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This study delved into the acoustic spectrum of bubble clusters, each consisting of 352 vapor bubbles across volume fractions ranging from 0.005–40%. The clusters, organized in five distinct layers, were modeled using the Volume of Fluid (VOF) method to capture the bubble interfaces, and the Ffowcs Williams-Hawkings (FW-H) methodology to compute the far-field acoustic pressure from bubble collapse. Further analysis revealed distinct sound pressure behaviors across different volume fractions: For 25%-40%, time-domain analysis shows that the peak acoustic pressure pulses from the two innermost layers of bubbles are significantly higher than those from the outer layers. In the frequency domain, the octave decay rate of the acoustic pressure levels is relatively low, around − 3dB/octave. For 0.5%-25%, four acoustic pressure pulses with similar widths and peak values were observed in the time domain. In the frequency domain, there are three distinct peaks in sound pressure levels(SPL), directly linked to the difference in collapse times of bubbles within the cluster, and the octave decay rate accelerates as the volume fraction decreases, stabilizing at -6dB/octave when the volume fraction is reduced to 17.5%. For 0.005%-0.5%, as the volume fraction decreases from 0.5–0.1%, the number of acoustic pressure pulses significantly reduces. Below 0.1% volume fraction, only a single wider pulse is observed. In the frequency domain, the octave decay rate gradually increases with decreasing volume fraction, significantly exceeding − 10dB/octave when it drops below 0.1%, reaching up to -11.7dB/octave.

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Section: Collapse Of Bubble Clustersmentioning

confidence: 76%

Section: Numerical Methods For Vapor Bubblesmentioning

confidence: 99%

Section: Acoustic Analogymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical study of the acoustic spectrum of bubble clusters

Deng,

Zhao,

Zhang

et al. 2024

Preprint

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Numerical Simulation of Molten Steel Flow Field in a Ladle Induced by Low‐Frequency High‐Power Ultrasound

Guo,

Chen,

et al. 2024

steel research int.

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To encourage the use of ultrasound in the calcium treatment of molten steel, this study utilizes the volume‐of‐fluid (VOF) method combined with a mixture model to analyze the distribution of the flow field in molten steel when ultrasound is applied. The effects of low‐frequency, high‐power ultrasound on the pressure field, volume fraction of cavitation bubbles, velocity distribution, and turbulence intensity are investigated. The results reveal a pattern of alternating positive and negative pressure in the pressure field during each cycle, with the lowest pressure measuring −9.63 × 104 Pa at 96 kW. The cavitation bubbles are concentrated in the intense cavitation area beneath the ultrasonic probe, exhibiting a maximum volume fraction of 2.50 × 10−2. The axial velocity peaks at the central axis, whereas the radial velocity is negligible. The maximum axial velocity increases from 0.36 m/s at 48 kW to 0.82 m/s at 120 kW. This velocity trend mirrors the turbulence intensity distribution, with the highest turbulence intensity of 276 at 96 kW. These findings provide a theoretical basis for low‐frequency, high‐power ultrasound to improve the calcium treatment of molten steel. The outcomes of the numerical simulation closely align with the experimental results, substantiating their reliability through a comparison with published studies.

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