Shock wave emission from a hemispherical cloud of bubbles in non-Newtonian fluids

Brujan, Emil-Alexandru; Matsumoto, Yoichiro

doi:10.1016/j.jnnfm.2013.12.003

Cited by 11 publications

(9 citation statements)

References 22 publications

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“…Because of the high velocities and consequent high Reynolds number during the growth and collapse of a bubble, viscosity is found to play a negligible role in the collapse of a cavitation bubbles. For bubbles in a very viscous fluid (more than thousands of time the viscosity of water), the viscosity would slow down the collapse process (Tinguely, 2013;Brujan and Matsumoto, 2014). In the present study, the flow surrounding the bubble is assumed inviscid, incompressible and irrotational.…”

Section: Basic Formulasmentioning

confidence: 97%

“…However, bubbles do not exist in isolation in many practical situations and their dynamics show collective behavior due to inter-bubble interactions. Brujan et al (2011Brujan et al ( , 2012Brujan et al ( , and 2014 studied the dynamics of bubble cloud near a rigid wall. They found the main mechanism of bubble clouds collapsing near a boundary is the high pressure generated inside the cloud at the minimum volume.…”

Section: Discusstionmentioning

confidence: 99%

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Analysis of pressure field generated by a collapsing bubble

Han

Zhang

et al. 2016

Ocean Engineering

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This paper is concerned with the dynamic pressure induced by a collapsing bubble, based on the potential flow theory coupled with the boundary element method. The pressure is calculated using the Bernoulli equation, where the partial derivative of the potential in time is calculated using the auxiliary function method. The numerical results agree well with experimental results, in terms of bubble shape and pressure fields. There are two root causes of the bubble induced pressure and the dynamic pressure is decomposed into two parts correspondingly. The first part p g is associated with the imbalanced pressure between the bubble gas and the ambient flow, which measures the contribution of the high pressure gas to the dynamic pressure. The second part p m is caused by the bubble motion, which helps evaluate the contribution of the jet impact. The variation of p g has the same pattern with the gas pressure. p m at the wall center reaches its first peak soon after the jet impact, and then decreases due to the reduction of jet velocity. As the toroidal bubble migrates towards the wall, p m may rise again. We also investigate the influences of dimensionless parameters on the pressure field induced by a gas/cavitation bubble.

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Section: Basic Formulasmentioning

confidence: 97%

Section: Discusstionmentioning

confidence: 99%

Analysis of pressure field generated by a collapsing bubble

Han

Zhang

et al. 2016

Ocean Engineering

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“…The images recorded and shown in figure 2 for the eroded tip also show a cluster/collection of bubbles formed at the surface of the piston. These collections or clusters 13,14 of bubbles have been studied in a variety of experimental scenarios [34][35][36] and liquid matrices. However, it appears for the lipid material (e.g.…”

Section: Please Do Not Adjust Marginsmentioning

confidence: 99%

Cavitation clusters in lipid systems – surface effects, local heating and streamer formation

Birkin

Foley

Truscott

et al. 2017

Phys. Chem. Chem. Phys.

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Cavitation clusters and streamers are characterised in lipid materials (specifically sunflower oil) and compared to water systems. The lipid systems, which are important in food processing, are studied with high-speed camera imaging, laser scattering and pressure measurements. In these oils, clusters formed at an aged (roughened) tip of the sound source (a piston like emitter, PLE) are shown to collapse with varied periodicity in relation to the drive amplitude employed. A distinct streamer (an area of increased flow emanating from the cavitation cluster) is seen in the lipid media which is collimated directly away from the tip of the PLE source whereas in water the cavitation plume is visually less distinct. The velocity of bubbles in the lipid streamer near the cluster on the order of 10 m s -1. Local heating effects, within the streamer, are detected using a dual thermocouple measurement at extended distances. Viscosity, temperature and the outgassing within the oils are suggested to play a key role in the streamer formation in these systems.

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“…The study on the interaction of multi-bubbles is much more challenging and associated with relatively few studies in the literature. In practice, however, bubbles tend to appear in clusters, clouds, filaments or groups, rather than in isolation [21][22][23][24] , and the interactions between bubbles are therefore inevitable. This is true to a wide range of bubble applications, which includes not only the classic areas such as cavitation erosion 25,26 and noise in hydraulic machinery 27-29 , but also sonochemistry 30,31 , sonoluminescence 30,32 , ultrasonic cleaning [33][34][35] and seismic airgun bubble arrays 36,37 , as well as medical applications including sonoporation 38,39 , ultrasound lithotripsy [40][41][42] and so on.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on interaction and coalescence of synchronized multiple bubbles

Cui

Wang

et al. 2016

Physics of Fluids

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Experiments are carried out on the interaction and coalescence of two, three and four bubbles with approximately the same sizes, distributed evenly and symmetrically. The bubbles are generated simultaneously by electric discharges, using an in-house designed series circuit, and their interaction is captured using a high-speed camera. Particular attentions are paid to if/when coalescence of bubbles happens, and the motion of the joined bubbles. Some new features are observed, which depend mainly on the dimensionless distance γ bb = d bb /R max , where d bb is the inter-bubble distance and R max is the maximum bubble radius. For γ bb > 2, a jet forms and penetrates each side bubble, directed to the center of the configuration, resulting in a protrusion. Towards the end of collapse, a large portion of bubble gases is compressed into the protrusion from the main part of the toroidal bubble. For γ bb < 2, the bubbles coalesce during expansion, and the part of the joined bubble's surface distal from the center of the configuration collapses faster than elsewhere. The experiments show that the oscillation period of multi-bubbles does not change appreciably without coalescence but increases significantly with coalescence. For three bubbles initiated at collinear positions with γ bb > 2, the jets that form from the side bubbles are towards the middle, and the middle bubble splits into two parts, moving towards the two side bubbles. For γ bb < 2, the side bubbles merge with the middle bubble during expansion, forming an ellipsoid bubble; the joined bubble collapses predominantly from two sides, where two inward jets form towards the end of collapse.

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Shock wave emission from a hemispherical cloud of bubbles in non-Newtonian fluids

Cited by 11 publications

References 22 publications

Analysis of pressure field generated by a collapsing bubble

Analysis of pressure field generated by a collapsing bubble

Cavitation clusters in lipid systems – surface effects, local heating and streamer formation

Experimental study on interaction and coalescence of synchronized multiple bubbles

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