Journal articles: 'Cavitation clouds'

1

Ahn, Byoung-Kwon, So-Won Jeong, Cheol-Soo Park, and Gun-Do Kim. "An Experimental Investigation of Coherent Structures and Induced Noise Characteristics of the Partial Cavitating Flow on a Two-Dimensional Hydrofoil." Fluids 5, no. 4 (November 3, 2020): 198. http://dx.doi.org/10.3390/fluids5040198.

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In many practical submerged objects, various types of cavitation such as bubble, sheet, and cloud cavitation occur according to flow conditions. In spite of numerous theoretical, numerical, and experimental studies, there are still many problems to be solved such as induced noise and damage potential due to cavitation. In this paper, an experimental investigation on coherent structures and induced noise characteristics of partial cavitation on a two-dimensional hydrofoil is presented. Experiments that focused on the dynamics of cavitation clouds were conducted in a cavitation tunnel. Using high-speed visualization, the series process consisting of inception, growth, and desinence of the partial cavity was investigated. The noise generated during the process was also measured, and the correlation with the cavity pattern was examined. The results show that the periodic behavior of cavitation clouds is directly reflected in the noise characteristics. In addition, the visualization of coherent structures within the sheet and cloud cavity provides a qualitative understanding of hairpin vortices and their packets, which play a dominant role in turbulent cavitating flows.

2

Li, Lidong, Yan Xu, Mingming Ge, Zunce Wang, Sen Li, and Jinglong Zhang. "Numerical Investigation of Cavitating Jet Flow Field with Different Turbulence Models." Mathematics 11, no. 18 (September 19, 2023): 3977. http://dx.doi.org/10.3390/math11183977.

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In numerous industries such as drilling, peening, cleaning, etc., a cavitating jet is adopted. However, it is challenging to simulate the cavitating flow field numerically with accuracy. The flow field of the organ pipe cavitation nozzle is simulated in this research using the RNG k−ε, DES, and LES turbulence models. The LES model can more accurately predict the periodic shedding of a cavitating cloud, which is basically consistent with the jet morphology captured with a high−speed camera. The flow pattern, cavitating cloud evolution and shedding period of a cavitating jet are analyzed. The findings demonstrate that the LES model produces a cavitating effect inside the nozzle that is superior to those produced by the RNG k−ε and DES models. The vortex rings in the diffusion section are simulated using the LES model, which accelerates cavitation. The cavitating clouds of the organ pipe nozzle show periodic evolutions, with stages of generation, development, shedding and collapse. The periodic shedding of the cavitating clouds exhibits a similar pattern in the vorticities simulated using the LES model, and the vorticities display the small-scale structures where the cavitating bubbles collapse. This study can provide a reference for the simulation of a cavitating jet and the analysis of the cavitating mechanism.

3

Wang, Hao, Jian Feng, Keyang Liu, Xi Shen, Bin Xu, Desheng Zhang, and Weibin Zhang. "Experimental Study on Unsteady Cavitating Flow and Its Instability in Liquid Rocket Engine Inducer." Journal of Marine Science and Engineering 10, no. 6 (June 12, 2022): 806. http://dx.doi.org/10.3390/jmse10060806.

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To study instability in the unsteady cavitating flow in a liquid rocket engine inducer, visualization experiments of non-cavitating and cavitating flows inside a model inducer were carried out at different flow conditions. Visual experiments were carried out to capture the evolution of non-cavitating and cavitating flows in a three-bladed inducer by using a high-speed camera. The external characteristic performance, cavitation performance, and pressure pulsation were analyzed based on the observation of non-cavitation and cavitation development and their instabilities. Under non-cavitation conditions, the change of flow rate has a significant impact on the pressure pulsation characteristics in the inducer. The occurrence of cavitation aggravated the instability of the flow and caused the intensity of pressure pulsation at each measuring point to increase. This cavitation structure has strong instability, and the tail region is often accompanied by shedding cavitation clouds perpendicular to the blade surface.

4

REISMAN, G. E., Y. C. WANG, and C. E. BRENNEN. "Observations of shock waves in cloud cavitation." Journal of Fluid Mechanics 355 (January 25, 1998): 255–83. http://dx.doi.org/10.1017/s0022112097007830.

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This paper describes an investigation of the dynamics and acoustics of cloud cavitation, the structures which are often formed by the periodic breakup and collapse of a sheet or vortex cavity. This form of cavitation frequently causes severe noise and damage, though the precise mechanism responsible for the enhancement of these adverse effects is not fully understood. In this paper, we investigate the large impulsive surface pressures generated by this type of cavitation and correlate these with the images from high-speed motion pictures. This reveals that several types of propagating structures (shock waves) are formed in a collapsing cloud and dictate the dynamics and acoustics of collapse. One type of shock wave structure is associated with the coherent collapse of a well-defined and separate cloud when it is convected into a region of higher pressure. This type of global structure causes the largest impulsive pressures and radiated noise. But two other types of structure, termed ‘crescent-shaped regions’ and ‘leading-edge structures’ occur during the less-coherent collapse of clouds. These local events are smaller and therefore produce less radiated noise but the interior pressure pulse magnitudes are almost as large as those produced by the global events.The ubiquity and severity of these propagating shock wave structures provides a new perspective on the mechanisms reponsible for noise and damage in cavitating flows involving clouds of bubbles. It would appear that shock wave dynamics rather than the collapse dynamics of single bubbles determine the damage and noise in many cavitating flows.

5

Yuan, Miao, Yong Kang, Hanqing Shi, Dezheng Li, and Hongchao Li. "Experimental Investigation on the Characteristic of Hydrodynamic-Acoustic Cavitation (HAC)." Journal of Marine Science and Engineering 10, no. 3 (February 22, 2022): 309. http://dx.doi.org/10.3390/jmse10030309.

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This study aimed to investigate the Cavitation dynamics of Hydrodynamic-acoustic cavitation by employing experimental methods. The spatial distribution of cavitation clouds, the temporal and spatial distribution achieved by cavitation clouds, and the main flow structure in the flow field were extracted and analyzed by complying with the cavitating flow image captured with the high-speed camera. As indicated from the results, the widened cavitation region and the strength of cavitation under the synergy of ultrasound were reported. When the inlet pressure is 2 MPa, the average value of the volume-averaging cavitation intensity variable is 0.029, 0.058, and 0.092, respectively, and the corresponding growth rate is 95% and 58.5%. By adopting the Proper Orthogonal Decomposition method (POD), the ultrasound was revealed to primarily enhance the cavitation intensity by downregulating the cavitation threshold other than altering the large-scale vortex structure in the flow field. The high-frequency pressure pulsation of ultrasound strengthened the instability exhibited by the shear layer and induced small-scale vortex structures at the shear layer, which was suggested to be the more violently shed and collapse.

6

Simon, Alex, Connor Edsall, and Eli Vlaisavljevich. "Effects of pulse repetition frequency on bubble cloud characteristics and ablation for single-cycle histotripsy." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A247. http://dx.doi.org/10.1121/10.0016161.

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Histotripsy is a cavitation-based focused ultrasound ablation method in development for multiple clinical applications. This work investigates the effects of pulse repetition frequency (PRF) on histotripsy bubble cloud characteristics and ablative capabilities for single cycle histotripsy. Bubble clouds produced by a 500 kHz histotripsy system at PRF’s from 0.1 to 1000 Hz were visualized using high speed imaging in 1% agarose phantoms. Cloud images were analyzed to determine bubble cloud density (bubbles/mm2) and pulse-to-pulse bubble correlation. Ablation was assessed through lesion analysis in red blood cell (RBC) phantoms. Results showed cavitation clouds generated at low PRF were characterized by consistently dense bubble clouds (49.6 ± 7.7 bubbles/mm2, 1 Hz) that closely matched regions above the histotripsy intrinsic threshold. Bubble clouds formed at high PRF had significantly lower cloud density (20.0 ± 8.3 bubbles/mm2, 1000 Hz). In addition, bubbles in higher PRF clouds had significantly increased pulse-to-pulse correlation, characteristic of what has been reported as the cavitation memory effect. Results from RBC ablation showed that higher PRF generated lesions had lower adherence to the focal region and less repeatability compared to low PRF ablations. This study demonstrates essential differences in bubble cloud characteristics that will help guide future histotripsy pulsing strategies.

7

del Campo, David, R. Castilla, GA Raush, PJ Gamez-Montero, and E. Codina. "Pressure effects on the performance of external gear pumps under cavitation." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 16 (February 24, 2014): 2925–37. http://dx.doi.org/10.1177/0954406214522990.

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The numerical analysis of an external gear pump with cavitation effects has been validated with experimental data obtained by applying Time-Resolved Particle Image Velocimetry. The effect of inlet and outlet pressure on volumetric efficiency has been studied numerically. First, the Particle Image Velocimetry method was used to analyze the two-dimensional velocity field in the middle plane of the suction chamber of the gear pump. The main improvement, with respect to previous similar analysis is the use of alginate micro particles as tracers. It is seen that the two-dimensional model is able to characterize the flow field of the real pump in the region of the inlet chamber in which cavitation is expected. In a previous study, it was seen that a cavitation cloud acted as a virtual contact point at low pressure, being responsible for an increase on the volumetric efficiency. The first set of simulations represents the pump working with high outlet pressure. Now, the cavitation cloud is not present and cavitation no longer helps to improve the efficiency of the pump. The second set of simulations represents the pump with an inlet loss factor, which implies a mean inlet pressure below atmospheric conditions. This allows cavitation clouds to propagate upstream. Despite the larger cavitation clouds, volumetric efficiency only drops at high operating velocities, when some clouds become trapped between gears and casing and are transported to the pressure side.

8

Cui, Yanyu, Manjun Zhao, Qingmiao Ding, and Bin Cheng. "Study on Dynamic Evolution and Erosion Characteristics of Cavitation Clouds in Submerged Cavitating Water Jets." Journal of Marine Science and Engineering 12, no. 4 (April 10, 2024): 641. http://dx.doi.org/10.3390/jmse12040641.

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The dynamic evolution behavior of submerged water jet cavitation clouds was studied by combining experiments and simulation. The formation, development, shedding, and collapsing process of a void cloud was analyzed by high-speed camera technology, and the influence of jet pressure was studied. Cavitation water jet erosion experiments were carried out on AL6061 specimens with standard cylindrical nozzles, and the correlation between cavitation cloud evolution and material erosion was studied by surface analysis. The results showed that the evolution of a cavitation cloud has obvious periodicity, that one period is about 0.8 ms, and its action region can be divided according to the attenuation rate of the jet velocity of the nozzle axis. The attenuation rate of the jet velocity at the nozzle axis in the central jet action zone is less than or equal to 82.5%, in the mixed action zone greater than 82.5% and less than 96%, and in the cavitation action zone greater than or equal to 96%. The erosion damage characteristics in different regions of the mixed action zone are significantly different.

9

Yang, Yongfei, Wei Li, Weidong Shi, Ling Zhou, and Wenquan Zhang. "Experimental Study on the Unsteady Characteristics and the Impact Performance of a High-Pressure Submerged Cavitation Jet." Shock and Vibration 2020 (June 16, 2020): 1–15. http://dx.doi.org/10.1155/2020/1701843.

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High-pressure submerged cavitation jet is widely used in the fields of material peening, petroleum drilling, and ocean engineering. The impact performance of the jet with intensive cavitation is related to the factors such as working condition and the nozzle geometry. To reveal the relationship between the nozzle divergent angle and the jet pressure on the unsteady characteristics of the jet, high-speed photography with frame rate of 20000 fps is used to record the image of the cavitation clouds. Grayscale analysis algorithm developed in MATLAB is used to study the effects of injecting condition on the special structure, unsteady characteristics, and shedding frequency of the cavitation bubbles. The impact load characteristics of the cavitation jet with different cavitation numbers and stand-off distances are recorded using a high-response pressure transducer. It is found that the cavitation number is the main factor affecting the cavitation morphology of the submerged jet. The lower the cavitation number is, the more intense the cavitation occurs. The outlet divergent angle of the convergent-divergent nozzle also has a significant influence on the development of the cavitation clouds. In the three nozzles with the outlet divergent angles of 40°, 80°, and 120°, the highest bubble concentration is formed usinga nozzle with a divergent angle of 40°, but the high-concentration cavitating bubbles are only distributed in a very small range of the nozzle outlet. The cavities generated by using the nozzle with a divergent angle of 80° can achieve good results in terms of concentration and distribution range, while the nozzle with divergent angle of 120° has lower cavitation performance due to the lack of the constraint at the outlet which intensifies the shear stress of the jet. According to the result of frame difference method (FDM) analysis, the jet cavitation is mainly formed in the vortex structure generated by the shearing layer at the nozzle exit, and the most severe region in the collapse stage is the rear end of the downstream segment after the bubble cloud sheds off. The impact load of the cavitation jet is mainly affected by the stand-off distance of the nozzle from the impinged target, while the nozzle outlet geometry also has an effect on the impact performance. Optimizing the stand-off distance and the outlet geometry of the nozzles is found to be a good way to improve the performance of the cavitation jet.

10

Huang, Si, Yuxiong Hu, Yifeng Wei, and Yushi Mo. "Analysis of Cavitation Flow Performance in Centrifugal Pump Using OpenFOAM." Journal of Physics: Conference Series 2610, no. 1 (October 1, 2023): 012023. http://dx.doi.org/10.1088/1742-6596/2610/1/012023.

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Abstract In order to explore the cavitation mechanism and cavitation cloud development process of centrifugal pump, OpenFOAM7.0 open-source software was used to simulate the unsteady cavitation gas-liquid two-phase flow of IS125 centrifugal pump under different flow conditions. Based on the flow field simulation results, the relationship between the flow rate of the centrifugal pump and the NPSHr was predicted and compared with the experimental data. The comparison showed that it is feasible to use OpenFOAM software to simulate the cavitation flow of centrifugal pump under design condition. Under the design condition, when NPSHa was different, the distribution of cavitation clouds in each blade channel was asymmetric. With the decrease of NPSHa, cavitation clouds continue to develop downstream in the impeller channel and appear on the blade pressure surface. Regardless of whether cavitation occurred in the centrifugal pump, the pressure coefficient showed periodic pulsation, and the pulsation number of the impeller in a rotation cycle was equal to the number of blades of the impeller. The research results can provide an effective open-source software calculation method for centrifugal pump performance prediction.

11

Yamaguchi, A., and S. Shimizu. "Erosion Due to Impingement of Cavitating Jet." Journal of Fluids Engineering 109, no. 4 (December 1, 1987): 442–47. http://dx.doi.org/10.1115/1.3242686.

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Cavitation erosion produced by impingent of cavitating jet was experimentally studied with specimens of aluminum alloy in high water base fluid of chemical solution type and tap water. Furthermore, the behavior of impinging cavity clouds was observed through instantaneous photographs.

12

Kadivar, Ebrahim, Mazyar Dawoodian, Yuxing Lin, and Ould el Moctar. "Experiments on Cavitation Control around a Cylinder Using Biomimetic Riblets." Journal of Marine Science and Engineering 12, no. 2 (February 6, 2024): 293. http://dx.doi.org/10.3390/jmse12020293.

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Experimental investigations were conducted to uncover the impact of cavitation control—through the use of biomimetic riblets on cavitating flows around a circular cylinder. First, the dynamics of cavitation in the flow behind a finite cylinder (without riblets) was unveiled by visualizing the cavitation clouds and measuring the lift force fluctuations acting on the cylinder. Second, in a significant step forward, a comprehensive explanation was provided for the cavitation control methods using two bio-inspired riblet morphologies positioned in different orientations and locations on the cylinder. For the first time, the impacts of these tiny formations on the flow dynamics and the associated cavitation process were scrutinized. This showed that scalloped riblets, with their curved design, induced secondary vortices near their tips and distorted primary streamwise vortices, and that high velocity gradients near the jagged pattern peaks of sawtooth riblets delayed flow separation, which affected cavitation.

13

Maeda, Kazuki, and Tim Colonius. "Bubble cloud dynamics in an ultrasound field." Journal of Fluid Mechanics 862 (January 16, 2019): 1105–34. http://dx.doi.org/10.1017/jfm.2018.968.

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The dynamics of bubble clouds induced by high-intensity focused ultrasound is investigated in a regime where the cloud size is similar to the ultrasound wavelength. High-speed images show that the cloud is asymmetric; the bubbles nearest the source grow to a larger radius than the distal ones. Similar structures of bubble clouds are observed in numerical simulations that mimic the laboratory experiment. To elucidate the structure, a parametric study is conducted for plane ultrasound waves with various amplitudes and diffuse clouds with different initial void fractions. Based on an analysis of the kinetic energy of liquid induced by bubble oscillations, a new scaling parameter is introduced to characterize the dynamics. The new parameter generalizes the cloud interaction parameter originally introduced by d’Agostino & Brennen (J. Fluid Mech., vol. 199, 1989, pp. 155–176). The dynamic interaction parameter controls the energy localization and consequent anisotropy of the cloud. Moreover, the amplitude of the far-field, bubble-scattered acoustics is likewise correlated with the proposed parameter. Findings of the present study not only shed light on the physics of cloud cavitation, but may also be of use for the quantification of the effects of cavitation on outcomes of ultrasound therapies including high-intensity focused ultrasound-based lithotripsy.

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SAITO, Yasuhiro, and Keiichi SATO. "Instantaneous Behavior of Cavitation Clouds at Impingement of Cavitating Water-Jet." Progress in Multiphase Flow Research 2 (2007): 47–53. http://dx.doi.org/10.3811/pmfr.2.47.

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YANG, Yongfei, Wei LI, Weidong SHI, Chuan WANG, and Wenquan ZHANG. "Experimental Study on Submerged High-Pressure Jet and Parameter Optimization for Cavitation Peening." Mechanics 26, no. 4 (September 15, 2020): 346–53. http://dx.doi.org/10.5755/j01.mech.26.4.27560.

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To increase the performance of high pressure submerged cavitation jet that has been used for cavitation peening, the effect of stand-off distance and the nozzle geometry on the impact capacity is investigated and optimized. High speed photography of the cavitation bubble clouds taken to reveal the unsteady characteristics of the cavitating jet. The impact ability of the jet with different nozzles and standoff distance is tested using Al 1060 at first, and the optimized jet is used then for cavitation peening on 304 stainless steel. The surface profile as well as the grain structures before and after peening using different nozzles are observed from SEM images. It is found that, the divergent angle of the nozzle has a great effect on the impact capability of the submerged high-pressure jet, which is important for improving the peening efficiency. In the nozzles with divergent angle 40°, 60° and 80°, the 60° nozzle shows the best performance. After peening, grain cells under the metal surface are changed and a twin layer is formed. The current research reveals the transient characteristics of the submerged cavitation jet and main factors that affect its impact rate, which provides guide for the nozzle design and application for the high-pressure cavitation jet peening.

16

Soeira, Thiago Vinicius Ribeiro, Guilherme Barbosa Lopes Junior, Cristiano Poleto, and Julio Cesar de Souza Inácio Gonçalves. "Quantitative characterization of volume of cavities in hydrodynamic cavitation device using computational fluid dynamics." Revista Eletrônica em Gestão, Educação e Tecnologia Ambiental 24 (December 4, 2020): e28. http://dx.doi.org/10.5902/2236117062707.

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Hydrodynamic cavitation has been extensively studied for its potential to remove emerging pollutants. Despite the advance of the experimental studies involving this phenomenon, computational studies that evaluate the influence of the geometry of the cavitation devices on the flow parameters are still necessary. The purpose of this article was to evaluate the influence of the change in the geometry of a Venturi device on the volume of cavities formed in its divergent section using Computational Fluid Dynamics (CFD). The geometric parameters modified in the Venturi were: the diffuser angle and the relation between the height and the width of the throat (h/w). The volume of cavities is an important parameter because it influences the cavitation intensity. A cavitational bench system was constructed in order to obtain input data for simulation. The results showed that the increase in the diffuser angle from 6.5° to 18.5° gradually reduced the volume of cavities from 93 mm3 to 10 mm3. Between the relations h/w = 0.05 and h/w = 0.45 was observed the formation of cavities between 106 mm3 and 77 mm3, however between h/w = 0.45 and h/w = 1.0 there was the formation of 213 mm3. Therefore, Venturi’s with diffuser angle less than 6.5º and relation h/w greater than 0.45 produce greater volume of cavities. The greater volume of cavities will not necessarily produce greater cavitational intensity, since cavitation clouds can be formed and reduce the implosion intensity of the cavitation bubbles.

17

CALLENAERE, MATHIEU, JEAN-PIERRE FRANC, JEAN-MARIE MICHEL, and MICHEL RIONDET. "The cavitation instability induced by the development of a re-entrant jet." Journal of Fluid Mechanics 444 (September 25, 2001): 223–56. http://dx.doi.org/10.1017/s0022112001005420.

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The instability of a partial cavity induced by the development of a re-entrant jet is investigated on the basis of experiments conducted on a diverging step. Detailed visualizations of the cavity behaviour allowed us to identify the domain of the re-entrant jet instability which leads to classical cloud cavitation. The surrounding regimes are also investigated, in particular the special case of thin cavities which do not oscillate in length but surprisingly exhibit a re-entrant jet of periodical behaviour. The velocity of the re-entrant jet is measured from visualizations, in the case of both cloud cavitation and thin cavities. The limits of the domain of the re-entrant jet instability are corroborated by velocity fluctuation measurements. By varying the divergence and the confinement of the channel, it is shown that the extent of the auto-oscillation domain primarily depends upon the average adverse pressure gradient in the channel. This conclusion is corroborated by the determination of the pressure gradient on the basis of LDV measurements which shows a good correlation between the domain of the cloud cavitation instability and the region of high adverse pressure gradient. A simple phenomenological model of the development of the re-entrant jet in an adverse pressure gradient confirms the strong influence of the pressure gradient on the development of the re-entrant jet and particularly on its thickness. An ultrasonic technique is developed to measure the re-entrant jet thickness, which allowed us to compare it with the cavity thickness. By considering an estimate of the characteristic height of the perturbations developing on the interface of the cavity and of the re-entrant jet, it is shown that cloud cavitation requires negligible interaction between both interfaces, i.e. a thick enough cavity. In the case of thin cavities, this interaction becomes predominant; the cavity interface breaks at many points, giving birth to small-scale vapour structures unlike the large-scale clouds which are periodically shed in the case of cloud cavitation. The low-frequency content of the cloud cavitation instability is investigated using spectral analysis of wall pressure signals. It is shown that the characteristic frequency of cloud cavitation corresponds to a Strouhal number of about 0.2 whatever the operating conditions and the cavity length may be, provided the Strouhal number is computed on the basis of the maximum cavity length. For long enough cavities, another peak is observed in the spectra, at lower frequency, which is interpreted as a surge-type instability. The present investigations give insight into the instabilities that a partial cavity may undergo, and particularly the re-entrant jet instability. Two parameters are shown to be of most importance in the analysis of the re-entrant jet instability: the adverse pressure gradient and the cavity thickness compared to the re-entrant jet thickness. The present results allowed us to conduct a qualitative phenomenological analysis of the stability of partial cavities on cavitating hydrofoils. It is conjectured that cloud cavitation should occur for short enough cavities, of the order of half the chordlength, whereas the instability often observed at the limit between partial cavitation and super-cavitation is here interpreted as a cavitation surge-type instability.

18

Kucera, A., and J. R. Blake. "Approximate methods for modelling cavitation bubbles near boundaries." Bulletin of the Australian Mathematical Society 41, no. 1 (February 1990): 1–44. http://dx.doi.org/10.1017/s0004972700017834.

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Approximate methods are developed for modelling the growth and collapse of clouds of cavitation bubbles near an infinite and semi-infinite rigid boundary, a cylinder, between two flat plates and in corners and near edges formed by planar boundaries. Where appropriate, comparisons are made between this approximate method and the more accurate boundary integral methods used in earlier calculations. It is found that the influence of nearby bubbles can be more important than the presence of boundaries. In confined geometries, such as a cylinder, or a cloud of bubbles, the effect of the volume change due to growth or collapse of the bubble can be important at much larger distances. The method provides valuable insight into bubble cloud phenomena.

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Dulin, Vladimir, Aleksandra Kravtsova, Dmitriy Markovich, Konstantin Pervunin, and Mikhail Timoshevskiy. "Application of Particle Image Velocimetry Technique to Study the Turbulent Structure of Cavitating Flows Around a Cascade of NACA0015 Series Hydrofoils." Siberian Journal of Physics 6, no. 4 (December 1, 2011): 70–81. http://dx.doi.org/10.54362/1818-7919-2011-6-4-70-81.

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The results of the application of PIV technique to study the turbulent structure of cavitating flows around a cascade of NACA0015 series hydrofoils are presented. Based on instantaneous velocity fields measured, spatial distributions of the mean velocity were calculated as well as the second-order statistical moments of liquid velocity fluctuations. Quantitative characteristics of the flows around the cascade and a solitary profile were demonstrated to be considerably different due mainly to discrepancies in distributions of the mean pressure and mutual impact of cavitation clouds

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Yamakoshi, Yoshiki, Jun Yamaguchi, Tomoyuki Ozawa, Tomoaki Isono, and Takuya Kanai. "Simultaneous Observation of Bubble Clouds and Microhollows Produced by Bubble Cloud Cavitation." Japanese Journal of Applied Physics 52, no. 7S (July 1, 2013): 07HF12. http://dx.doi.org/10.7567/jjap.52.07hf12.

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Zhang, Peng-Li, Shu-Yu Lin, Hua-Ze Zhu, and Tao Zhang. "Coupled resonance of bubbles in spherical cavitation clouds." Acta Physica Sinica 68, no. 13 (2019): 134301. http://dx.doi.org/10.7498/aps.68.20190360.

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Parlitz, U., R. Mettin, S. Luther, I. Akhatov, M. Voss, and W. Lauterborn. "Spatio–temporal dynamics of acoustic cavitation bubble clouds." Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences 357, no. 1751 (February 15, 1999): 313–34. http://dx.doi.org/10.1098/rsta.1999.0329.

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QIN, Z., K. BREMHORST, H. ALEHOSSEIN, and T. MEYER. "Simulation of cavitation bubbles in a convergent–divergent nozzle water jet." Journal of Fluid Mechanics 573 (February 2007): 1–25. http://dx.doi.org/10.1017/s002211200600351x.

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A model for simulating the process of growth, collapse and rebound of a cavitation bubble travelling along the flow through a convergent–divergent nozzle producing a cavitating water jet is established. The model is based on the Rayleigh–Plesset bubble dynamics equation using as inputs ambient pressure and velocity profiles calculated with the aid of computational fluid dynamics (CFD) flow modelling. A variable time-step technique is applied to solve the highly nonlinear second-order differential equation. This technique successfully solves the Rayleigh–Plesset equation for wide ranges of pressure variation and bubble original size and saves considerable computing time. Inputs for this model are the pressure and velocity data from CFD calculation. To simulate accurately the process of bubble growth, collapse and rebound, a heat transfer model, which includes the effects of conduction plus radiation, is developed to describe the thermodynamics of the incondensable gas inside the bubble. This heat transfer model matches previously published experimental data well. Assuming that single bubble behaviour also applies to bubble clouds, the calculated distance from the nozzle exit travelled by the bubble to the point where the bubble size becomes invisible is taken to be equal to the bubble cloud length observed. The predictions are compared with experiments carried out in a cavitation cell and show good agreement for different nozzles operating at different pressure conditions.

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Tsujino, T., A. Shima, and H. Nanjo. "Effects of Various Polymer Additives on Cavitation Damage." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 200, no. 4 (July 1986): 231–35. http://dx.doi.org/10.1243/pime_proc_1986_200_123_02.

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Cavitation damage tests in various polymer solutions have been carried out using a vibratory damage apparatus. The relation of weight loss-time, the damage patterns, the cavitation clouds and the damaged area in a polyacrylamide solution, a sodium carboxy-methylcellulose solution, a hydroxyethylcellulose solution, a guar gum solution and a polyethylene oxide solution are compared and are discussed. It is found that the weight losses in the PAM solution and the Polyox solution, which are more elastic, are smaller than the cases of the other polymer solutions and water after sixty minutes exposure to cavitation.

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Маргулис, И. М., В. Н. Половинкин, and А. И. Яшин. "Modern approaches to the description of the dynamics of cavitation bubbles and cavitation clouds." MORSKIE INTELLEKTUAL`NYE TEHNOLOGII)</msg>, no. 2(60) (May 25, 2023): 320–26. http://dx.doi.org/10.37220/mit.2023.60.2.040.

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В статье рассмотрены существующие подходы к описанию динамики кавитационных пузырьков и кавитационного облака и проблемы, которое возникают при моделировании высокоэнергетических кавитационных процессов, таких как ударные волны, кавитационная эрозия, свечение из пузырьков (сонолюминесценция), и т.д., в акустическом поле высокой интенсивности. Показано, что известная модель, основанная на уравнениях Келлера – Миксиса и Бъеркнеса, не соответствует целому ряду экспериментальных данных, полученных при исследовании «одиночного» кавитационного пузырька, неподвижно пульсирующего в пучности стоячей волны и «обычного» пузырька, движущегося в кавитационном облаке. Для устранения этих несоответствий предложена новая система уравнений, дополнительно учитывающая неравновесность процессов испарения и конденсации пара и неидеальность парогазовой смеси в пузырьке, а также поступательное движение пузырька. Показано, что при быстром сжатии пузырька пар внутри него не успевает конденсироваться и сильно демпфирует это сжатие. Полученное уравнение объясняет сильную зависимость интенсивности свечения «одиночных» пузырьков от температуры жидкости. Устранены противоречия при описании поступательного движения пузырьков, связанные с применением уравнения Бъеркнеса. Показано, что поступательно движущийся пузырек сжимается значительно слабее неподвижного, поскольку в фазе сжатия энергия радиального движения пузырька перетекает в энергию поступательного движения. Это позволяет объяснить причину различия в механизмах свечения пузырьков разных типов. «Одиночный» пузырек излучает свет в момент наибольшего сжатия вследствие нагрева парогазовой смеси до 5 000–10 000 К. Пузырьки в кавитационном облаке движутся поступательно, а их свечение, в отсутствие сильного сжатия, обусловлено микроразрядами в парогазовой фазе при деформации поверхностей пузырьков. The article discusses the existing approaches to the description of the dynamics of cavitation bubbles and cavitation clouds and the problems that arise during modeling of high-energy cavitation processes, such as shock waves, cavitation erosion, bubble glow (sonoluminescence), etc., in a high-intensity acoustic field. A well–known model based on the Keller-Miksis and Bjerknes equations does not correspond to several experimental data obtained in the study of a "single" cavitation bubble pulsating motionlessly in the antinode of a standing wave and an "ordinary" bubble moving in a cavitation cloud. To eliminate these inconsistencies, a new system of equations is proposed, which additionally considers the nonequilibrium processes of vapor evaporation and condensation and the imperfection of the vapor-gas mixture in the bubble, as well as the translational motion of the bubble. It is shown that with rapid compression of the bubble, the vapor inside it does not have time to condense and strongly damps this compression. Resulting equation demonstrates the strong dependence of the intensity of "single" bubble glow on the temperature of the liquid. Contradictions in the description of the translational motion of bubbles associated with the application of the Bjerknes equation are eliminated. Translationally moving bubble is compressed much weaker than a stationary one, since in the compression phase the energy of the radial motion of the bubble flows into the energy of translational motion. It helps explain the reason for the difference in the mechanisms of light emission from bubbles of different types. A "single" bubble emits light at maximal compression due to heating of the vapor-gas mixture up to 5000–10000 K. Bubbles in a cavitation cloud move progressively, and their glow, in the absence of strong compression, is caused by micro-discharges in the vapor-gas phase during deformation of the bubble surfaces.

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Leroux, Jean-Baptiste, Jacques Andre´ Astolfi, and Jean Yves Billard. "An Experimental Study of Unsteady Partial Cavitation." Journal of Fluids Engineering 126, no. 1 (January 1, 2004): 94–101. http://dx.doi.org/10.1115/1.1627835.

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Unsteady partial cavitation can cause damage to hydraulic machinery and understanding it requires knowledge of the basic physics involved. This paper presents the main results of a research program based on wall-pressure measurements aimed at studying unsteadiness in partial cavitation. Several features have been pointed out. For cavity lengths that did not exceed half the foil chord the cavity was stated to be stable. At the cavity closure a peak of pressure fluctuations was recorded originating from local cavity unsteadiness in the closure region at a frequency depending on the cavity length. Conversely, cavities larger than half the foil chord were stated to be unstable. They were characterized by a cavity growth/destabilization cycle settled at a frequency lower than the previous ones. During cavity growth, the closure region fluctuated more and pressure fluctuations traveling in the cavity wake were detected. When the cavity was half the foil chord, cavity growth was slowed down and counterbalanced by large vapor cloud shedding. When the cavity length was maximum (l/c∼0.7–0.8), it was strongly destabilized. The reason for such destabilization is discussed at the end of the paper. It is widely believed that the cavity instability originates from a process involving the shedding of vapor clouds during cavity growth, a re-entrant jet, and a shock wave phenomenon due to the collapse of a large cloud cavitation.

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Jablonská, Jana, Milada Kozubková, Daniel Himr, and Michal Weisz. "Methods of Experimental Investigation of Cavitation in a Convergent - Divergent Nozzle of Rectangular Cross Section." Measurement Science Review 16, no. 4 (August 1, 2016): 197–204. http://dx.doi.org/10.1515/msr-2016-0024.

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AbstractCavitation is a phenomenon with both positive and negative effects and with dynamic manifestations in hydraulic, food, chemical and other machinery. This article deals with the detection and dynamic behavior of cavitation clouds in water flows through a rectangular cross-section convergent-divergent nozzle. Cavitation was measured by methods applicable in engineering practice. Pressure, flow rate, noise, vibration, and amount of air dissolved in the liquid were measured and cavitation region was recorded with a high-speed camera. Evaluation of acquired images in connection with measured pressure pulsations and mechanical vibrations was performed with the use of the FFT method. In certain cases, dimensionless parameters were used to generalize the measurements. The results will be used to specify multiphase mathematical cavitation model parameters.

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Edsall, Connor W., Laura Huynh, Yasemin Yuksel Durmaz, Waleed Mustafa, and Eli Vlaisavljevich. "Nanoparticle-mediated histotripsy using dual-frequency histotripsy pulsing: Comparison of bubble-cloud characteristics and ablation efficiency." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A116. http://dx.doi.org/10.1121/10.0015730.

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Nanoparticle-mediated histotripsy (NMH) is a targeted ablation method using perfluorocarbon-filled nanoparticles to generate bubble-clouds at pressure levels (9–12 MPa) significantly below the histotripsy intrinsic threshold (>25 MPa). Prior studies have also shown a significant reduction in ablation efficiency compared to conventional histotripsy, likely from reduced bubble expansion and bubble-cloud density. Here, we investigate the bubble-cloud characteristics and ablation efficiency for NMH using dual-frequency pulsing. We hypothesize this method will increase ablation efficiency by increasing the bubble-cloud density and individual bubble expansion. High-speed optical imaging was used to characterize the cavitation threshold, cloud dimensions, and bubble-density of bubble clouds generated in agarose tissue phantoms, with and without perfluorohexane-filled nanocones, exposed to single-cycle dual-frequency pulses using a 500 kHz–3 MHz array transducer (1:1 pressure ratio). Ablation efficiency was investigated using red blood cell phantoms. Results showed dual-frequency NMH predictably produced smaller, denser, and more well-confined bubble-clouds and increased ablation efficiency compared to previous single-frequency studies, with complete ablation of the focal volume observed within 2000 pulses. This study demonstrates the potential of enhancing NMH ablation efficiency with dual-frequency pulsing and highlights the need for further studies to optimize NMH pulsing parameters for future clinical therapy development.

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Iida, Yasuo, Judy Lee, Teruyuki Kozuka, Kyuichi Yasui, Atsuya Towata, and Toru Tuziuti. "Optical cavitation probe using light scattering from bubble clouds." Ultrasonics Sonochemistry 16, no. 4 (April 2009): 519–24. http://dx.doi.org/10.1016/j.ultsonch.2008.12.003.

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Wang, Chuangnan, Thomas Connolley, Iakovos Tzanakis, Dmitry Eskin, and Jiawei Mi. "Characterization of Ultrasonic Bubble Clouds in A Liquid Metal by Synchrotron X-ray High Speed Imaging and Statistical Analysis." Materials 13, no. 1 (December 20, 2019): 44. http://dx.doi.org/10.3390/ma13010044.

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Quantitative understanding of the interactions of ultrasonic waves with liquid and solidifying metals is essential for developing optimal processing strategies for ultrasound processing of metal alloys in the solidification processes. In this research, we used the synchrotron X-ray high-speed imaging facility at Beamline I12 of the Diamond Light Source, UK to study the dynamics of ultrasonic bubbles in a liquid Sn-30wt%Cu alloy. A new method based on the X-ray attenuation for a white X-ray beam was developed to extract quantitative information about the bubble clouds in the chaotic and quasi-static cavitation regions. Statistical analyses were made on the bubble size distribution, and velocity distribution. Such rich statistical data provide more quantitative information about the characteristics of ultrasonic bubble clouds and cavitation in opaque, high-temperature liquid metals.

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Wang, Jiaxiang, Zunce Wang, Yan Xu, Yuejuan Yan, Xiaoyu Xu, and Sen Li. "Evolution of cavitation clouds under cavitation impinging jets based on three-view high-speed visualization." Geoenergy Science and Engineering 237 (June 2024): 212832. http://dx.doi.org/10.1016/j.geoen.2024.212832.

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Lafond, Maxime, Alice Ganeau, Olfa Ben Moussa, Frédéric Mascarelli, Gilles Thuret, Stefan Catheline, and Cyril Lafon. "Preliminary investigations on cavitation effects in the crystalline lens." Journal of the Acoustical Society of America 153, no. 3_supplement (March 1, 2023): A67. http://dx.doi.org/10.1121/10.0018187.

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Presbyopia is the age-related stiffening of the crystalline lens, reducing near vision. One of the main mechanisms of this lens stiffening is the formation of disulfide bonds. We propose ultrasonic cavitation to interact with the lens structure, disrupt disulfide bonds and restore flexibility. Here, we present early results on the feasibility of the technique. Cavitation was nucleated inside the porcine lenses using confocal transducers and signals emitted in the focal area were acquired using an imaging array and reconstructed using frequency-domain passive cavitation imaging. Peak negative pressure of 23MPa for 20-μs pulses at 1.1 MHz provided a clear chance of nucleating cavitation with our system. Exposures were performed during 10 seconds of cavitation at a PRF of 250 Hz. Cavitation clouds were clearly visible in B-mode images for both 6-months old and 3-years old porcine eyes. To provide initial safety data, the absence of cataract was confirmed on transparency images. Histology revealed no damage to the lens structure. A gel phantom with a disulfide bond-dependent hardening is proposed to investigate the potential for cavitation to disrupt the disulfide bonds.

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Ganeau, Alice, Maxime Lafond, Olfa Ben Moussa, Charles Mion, Sylvain Poinard, Frédéric Mascarelli, Stefan Catheline, Gilles Thuret, Philippe Gain, and Cyril Lafon. "Feasibility of cavitation nucleation in the crystalline lens." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A79. http://dx.doi.org/10.1121/10.0010719.

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Presbyopia is the age-related stiffening of the crystalline lens, reducing near vision. We propose ultrasonic cavitation to interact with the lens structure and restore its flexibility. Here, we present early results on the feasibility of the technique. First, the cavitation threshold was determined: the focus of a 4-elements transducer was placed in the lens nucleus in a porcine eye, and signals emitted in the focal area were acquired using an imaging array and reconstructed using frequency-domain passive cavitation imaging (PCI) with Richardson-Lucy deconvolution. Inharmonic emissions inside the lens were calculated, and we evidenced two distinct populations: low and high amount of signal inside the lens, when cavitation was absent or present, respectively. Peak negative pressure of 23 MPa for 20 μs pulses at 1.1 MHz provided a clear chance of nucleating cavitation with our system. Exposures were performed after 10 s of cavitation using a PRF of 250 Hz. Cavitation clouds were clearly visible in B-mode images for both 6-months old and 3-years old porcine eyes. The absence of cataract was confirmed on transparency images, and histology revealed no damages to the lens structure. These preliminary results are encouraging towards the application of cavitation in the crystalline lens.

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LI, Fuzhu. "Study on Dynamic Evolution of Cavitation Clouds and Optimization of Standoff Distance in Water Cavitation Peening." Journal of Mechanical Engineering 55, no. 9 (2019): 120. http://dx.doi.org/10.3901/jme.2019.09.120.

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Maxwell, Adam D., Tzu-Yin Wang, Charles A. Cain, J. Brian Fowlkes, Oleg A. Sapozhnikov, Michael R. Bailey, and Zhen Xu. "Cavitation clouds created by shock scattering from bubbles during histotripsy." Journal of the Acoustical Society of America 130, no. 4 (October 2011): 1888–98. http://dx.doi.org/10.1121/1.3625239.

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Maeda, Kazuki, Adam D. Maxwell, Tim Colonius, Wayne Kreider, and Michael R. Bailey. "Energy shielding by cavitation bubble clouds in burst wave lithotripsy." Journal of the Acoustical Society of America 144, no. 5 (November 2018): 2952–61. http://dx.doi.org/10.1121/1.5079641.

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Yang, Yuliang, Shimu Qin, Changchun Di, Junqi Qin, Dalin Wu, and Jianxin Zhao. "Research on Claw Motion Characteristics and Cavitation Bubbles of Snapping Shrimp." Applied Bionics and Biomechanics 2020 (September 21, 2020): 1–12. http://dx.doi.org/10.1155/2020/6585729.

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Snapping shrimp produces a high-speed jet through the rapid closure of the snapper claw, which stimulates the formation of cavitation bubbles of various shapes. In order to explore the fast motion characteristics of snapper claw, the formation and change process of cavitation, and the physical principles underlying the biological phenomena, the equivalent model of snapper claw was constructed through CT scanning technology. A high-speed camera was used to capture the claw’s motion characteristics, thereby simulating the production of cavitation bubbles by snapping shrimp. The results show that the rotation speeds of different species of snapping shrimps are different, as well as their motion characteristics. Cavitation is formed by the interaction of the pressure drop caused by the vortex at the nozzle with the inertia of the liquid inside the socket. Under the influence of the jet, the shapes of bubbles change from ring to cone, and eventually collapse into bubble clouds.

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Ohjimi, Saburo, Yasuhiro Sugimoto, and Keiichi Sato. "G505 Collapsing and Impulsive Behavior of Cavitation Clouds on Cavitating Water-jet Impinging on Solid Wall." Proceedings of the Fluids engineering conference 2007 (2007): _G505–1_—_G505–4_. http://dx.doi.org/10.1299/jsmefed.2007._g505-1_.

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Ohjimi, Saburo, Yasuhiro Sugimoto, and Keiichi Sato. "G505 Collapsing and Impulsive Behavior of Cavitation Clouds on Cavitating Water-jet Impinging on Solid Wall." Proceedings of the Fluids engineering conference 2007 (2007): _G505—a_. http://dx.doi.org/10.1299/jsmefed.2007._g505-a_.

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Zhang, Linrong, Guangjian Zhang, Mingming Ge, and Olivier Coutier-Delgosha. "Experimental Study of Pressure and Velocity Fluctuations Induced by Cavitation in a Small Venturi Channel." Energies 13, no. 24 (December 8, 2020): 6478. http://dx.doi.org/10.3390/en13246478.

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The purpose of this paper is to investigate experimentally the influence of the cavitation extent on the pressure and velocity fluctuations in a small convergent–divergent channel. The mean cavity length is determined from high-speed photography images. The mean pressure and the intensity of the pressure fluctuations are obtained from the transient pressure signals recorded by two pressure transducers at the inlet and outlet of the test section. The statistical turbulence quantities are derived from the instantaneous velocity fields measured by the laser-induced fluorescent particle image velocimetry (PIV-LIF) technique. The experimental results show that the decrease of the cavitation number (the increase in the extent of cavitation) leads to a rise in the turbulent fluctuations in the wake region due to the impact of vapour clouds collapsing, while the presence of a vapour phase is found to reduce the streamwise and cross-stream velocity fluctuations in the attached cavity. It might be attributed to two mechanisms: the presence of a vapour phase modifies the vortex-stretching process, and the cavitation compressibility damps out the turbulent fluctuations. Similar effects of cavitation are also observed in the pressure fluctuations.

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Farhat, M., A. Chakravarty, and J. E. Field. "Luminescence from hydrodynamic cavitation." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 467, no. 2126 (June 30, 2010): 591–606. http://dx.doi.org/10.1098/rspa.2010.0134.

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The majority of the research on cavitation luminescence has focused on the sonoluminescence or chemiluminescence generated by cavitation induced through ultrasound, with a lesser body of work on the luminescence induced by laser- or spark-induced cavitation. In such circumstances, the cavitation is generated in liquids where, on the broad scale, there is usually assumed to be no net liquid flow (although of course there are small-scale flows as a result of the cavitation itself, through radiation forces, streaming, microstreaming and turbulence). Little attention has been paid to the luminescence that accompanies (undesirable) cavitation in pumps and turbines or in marine propellers. In the present study, the sonoluminescence specific to air/water vapour bubbles, collapsing within a cavitation tunnel, is addressed. The particular case of leading edge cavitation over a two-dimensional hydrofoil is considered in detail. Hence, strong instabilities develop, causing the attached cavity to shed large clouds of micro bubbles. The spatial and temporal properties of the emitted luminescence were studied using an intensified charge coupled device video camera and a photomultiplier (PM). The light emission was found to extend downstream from the region of cavity closure, to the region where the travelling vortices collapse. Examination of the PM signal on short time scales showed that the emitted luminescence consisted of relatively intense flashes of short duration (as with other forms of luminescence). Individual flashes were often found to be clustered in time. Over longer time scales, clear evidence of periodicity was found in the PM signals. Further analysis showed that bursts of light were being emitted at the Strouhal frequency (for the shedding of transcient cavities).

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Yuan, Yue, and Yu An. "Abnormal heating peak of cavitation clouds deviating from their resonance point." International Communications in Heat and Mass Transfer 126 (July 2021): 105378. http://dx.doi.org/10.1016/j.icheatmasstransfer.2021.105378.

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Lu, Yuan, Joseph Katz, and Andrea Prosperetti. "Dynamics of cavitation clouds within a high-intensity focused ultrasonic beam." Physics of Fluids 25, no. 7 (July 2013): 073301. http://dx.doi.org/10.1063/1.4812279.

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URA, Naoya, Yasuhiro SUGIMOTO, and Keiichi SATO. "Influence of nozzle divergent shape on unsteady behavior of cavitation clouds." Proceedings of Conference of Hokuriku-Shinetsu Branch 2019.56 (2019): F024. http://dx.doi.org/10.1299/jsmehs.2019.56.f024.

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SATO, Keiichi, Saburo OHJIMI, and Yasuhiro SUGIMOTO. "Collapsing and Impulsive Behavior of Cavitation Clouds on Cavitating Water-Jet Impinging on Solid Wall(Fluids Engineering)." Transactions of the Japan Society of Mechanical Engineers Series B 75, no. 750 (2009): 241–50. http://dx.doi.org/10.1299/kikaib.75.750_241.

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Hutli, Ezddin, Milos Nedeljkovic, and Szabolcs Czifrus. "Study and analysis of the cavitating and non-cavitating jets - Part two: Parameters controlling the jet action and a new formula for cavitation number calculation." Thermal Science 24, no. 1 Part A (2020): 407–19. http://dx.doi.org/10.2298/tsci190428334h.

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This part of the paper presents the relation between the working conditions, nozzle geometry, nozzle diameter, and jet behavior. Experimental work has been made by impinging the submerged jets on the copper specimen as a target for a period of time. The mass loss and erosion rate at various conditions were measured, calculated and analyzed. For the visualization, a high-speed camera was used and the obtained data were processed to measure parameters which are used to characterize the clouds. Correlations among the jet dynamic power, the cavity length, erosion rate, and the pertinent experimental parameters are apparent. In addition, formulas are proposed to conveniently compare the efficiency of jetting systems based on working conditions. Based on the mathematical analyses of the obtained results a new form for cavitation number calculation is proposed.

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Wang, Ying, Tao Li, Ling Bing Kong, Huey Hoon Hng, and Pooi See Lee. "Gas flow induced by ultrasonic cavitation bubble clouds and surface capillary wave." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 61, no. 6 (June 2014): 1042–46. http://dx.doi.org/10.1109/tuffc.2014.3000.

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Chen, Hong, Xiaojing Li, and Mingxi Wan. "The inception of cavitation bubble clouds induced by high-intensity focused ultrasound." Ultrasonics 44 (December 2006): e427-e429. http://dx.doi.org/10.1016/j.ultras.2006.05.021.

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TAGUCHI, Yuta, and Keiichi SATO. "315 Appearance, Shedding and Impingement Motion of Cavitation Clouds in Water Jet." Proceedings of Conference of Hokuriku-Shinetsu Branch 2014.51 (2014): _315–1_—_315–2_. http://dx.doi.org/10.1299/jsmehs.2014.51._315-1_.

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Wang, Yi-Chun. "Effects of Nuclei Size Distribution on the Dynamics of a Spherical Cloud of Cavitation Bubbles." Journal of Fluids Engineering 121, no. 4 (December 1, 1999): 881–86. http://dx.doi.org/10.1115/1.2823550.

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The nonlinear dynamics of a spherical bubble cloud with nuclei size distribution are studied numerically. The spectrum of nuclei is assumed uniform initially. The simulations employ a nonlinear continuum bubbly mixture model with consideration of the presence of bubbles of different sizes. This model is then coupled with the Rayleigh-Plesset equation for the dynamics of bubbles. A numerical method based on the integral representation of the mixture continuity and momentum equations in the Lagrangian coordinates is developed to solve this set of integro-differential equations. Computational results show that the nuclei size distribution has significant effects on the cloud dynamics in comparison to the results for a single bubble size. One important effect is that the bubble collapse is always initiated near the surface of the cloud, even if the cloud has a very small initial void fraction. This effect has an important consequence, namely that the geometric focusing of the bubbly shock wave is always a part of the nonlinear dynamics associated with the collapse of a spherical cloud with nuclei size distribution. The strength of the shock and the oscillation structure behind the shock front are suppressed due to the effects of multiple bubble sizes. Far-field acoustic pressures radiated by two bubble clouds, one of equal-size bubbles and the other with bubble size distribution, are also compared. It is found that the cloud containing bubbles of different sizes emits a larger noise than the cloud of identical bubbles. Explanations for this effect are also presented.

Journal articles on the topic 'Cavitation clouds'

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