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Abstract Cavitation erosion is usually investigated with ultrasonic sonotrodes. Only a few attempts have been made to investigate chemical alloy deformation by cavitation erosion of technical alloys on the basis of repeated single bubbles. A single cavitation bubble can be induced by a concentrated laser pulse with high spatio-temporal repeatability. With a light microscope in-situ between two successive bubbles, the surface damage caused by a series of laser-generated single bubbles in water is shown in this work. In addition, our results indicate that even high-strength materials can be damaged by a single bubble, while not every single bubble causes a pit on the soft aluminum. The rate of pit accumulation was determined to be 2. 6 pits/bubble for aluminum and about 0. 3 0. 1 bumble for the two technical alloys, according to a series of photographs after each bubble.
Source link: https://doi.org/10.1007/s11249-022-01665-5
Both the impact jet speed and the wall's velocity are investigated, and the jet speed on the wall indicates a typical bimodal pattern, with only one perk observed on the pressure distribution for a single bubble collapse in a near-wall region. In addition, the studies showed that the wallu2013bubble distance has a greater effect on the wall pressure than the bubbleu2013bubble distance for double bubble interactions. Eventually, the simulation of the bubble cluster showed that the inner bubble has higher collapse severity than the outer layer bubble, while the side bubble collapse rate is more robust than the corner bubbles. The simulation of a series of cases shows that the proposed model is a good way to investigate realistic cavitation bubble dynamics.
Source link: https://doi.org/10.1063/5.0099989
A concentrated jet stream flows toward the boundary, with the avitation bubble growing and collapsing near a rigid boundary. Some of the jet stream passes through the plate, and thus the bubble appears as a pump transporting liquid from one side of the plate to the other. We first simulate fluid transport through a perforated rigid plate for a large number of parameters, and then compare some regimes with experiments using single laser-induced bubbles. With regard to the channel geometry, liquid viscosity, and standoff distances of the bubble to the plate, the resulting flux and generated velocity in the simulations are investigated. In general, high flow rates are achieved for long cylindrical channels with a similar width as the jet created by the collapsing bubble in general.
Source link: https://doi.org/10.1017/jfm.2022.480
By examining the acoustic field around the cavitation bubble, the nonlinear dynamic characteristics of coupled acoustic cavitation with double bubbles are investigated. When the coupled double bubble collapses, the bubble's acoustic cavitation is increased.
Source link: https://doi.org/10.7498/aps.72.20221571
Abstract We experimentally and numerically investigated the behaviour of a millimeter-sized cavitation bubble that formed near a solid surface in the present work. Here, the relative wall distance is a function of the distance between the bubble center and the specimen surface, as well as the maximum radius of the bubble. The damage characteristics were determined by the surface profiles and damage patterns. The behavior of a single bubble obtained in computations was compared to the measurements for shapes and collapsing times. E. g. , the computed characteristics of flow around a bubble on the solid surface, e. g. In addition, the behaviour of a microscopic bubble collapse near the surface was investigated to determine collapse-induced wall shear rate and flow around the collapsing bubble. Pits obtained by statistical analysis are also helpful in deriving loads caused by a single bubble collapse. Overall, this report contains significant information about single cavitation bubble dynamics and induced injuries.
Source link: https://doi.org/10.1115/omae2022-78536
parattice Boltzmann method pseudo-potential model is investigated, examining the effects of surface tension and initial input energy on cavitation properties based on a tunable-surface-tension high-density-ratio thermal lattice Boltzmann method pseudo-potential model. The simulation results show that increasing the surface tension for an infinite liquid will raise the collapse rate of cavitation bubbles, increasing the collapse pressure, speed, and temperature, while minimizing the bubble lifetime. The cavitation bubbles collapsing near a neutral wall with an increase in surface tension, the deposition pressure, temperature, and cavitation bubble lifetime trends are the same as in the infinite liquid. The maximum cavitation bubble radius in an infinite liquid is almost always proportional to the input initial energy. An increase in the surface energy reduces the maximum radius of the cavitation bubbles, while increasing the pressure and thermal energy reduces the maximum radius of the cavitation bubbles.
Source link: https://doi.org/10.1063/5.0113500
An urgent problem is the design of a separator under conditions of diminishing bubble formation volume. Dependents of the density function and the bubble geometric characteristics averaged over the ensemble's ensemble are determined by the design parameters, operating conditions, and physic-mechanical characteristics of the working medium, including the ratio of the gas and vapor contents in the bubble's inner cavity. The expressions for the given distribution function over the size of the bubbles and the ensemble-averaged characteristics of the bubble system can be used in the construction of an engineering method for estimating control equipment.
Source link: https://doi.org/10.1051/e3sconf/201914006005
The resonance frequency of bubbles in a columnar bubble cluster group can be determined by linear simplification of the bubbles'u2019 dynamic equation in this paper. The correlation coefficient between the bubbles in the columnar bubble group's resonance frequency and the Minnaert frequency of a single bubble is given. The initial radius of bubbles, the number of bubbles in the bubble group, and the distance between bubbles were all influenced by several variables, including the initial radius of bubbles, the number of bubbles in the bubble group, and the distance between bubbles. When the distance between bubbles rises to 20 times the bubblesu2019 initial radius, the coupling effect between bubbles can be dismissed, but after that the bubbles' resonance frequency in the bubble group rises to a single bubble's resonance frequency, it drifts to the resonance frequency of a single bubble's resonance frequency.
Source link: https://doi.org/10.3390/app9245292
In a porcine model, this report evaluated the performance of a closed-loop feedback controller. Calibration of the baseline cavitation level was performed for each targeted brain area by a FUS sonication in the presence of intravenously injected microbubbles at a low acoustic pressure without prompting BBB opening. Based on the baseline cavitation level, the target cavitation level was established for each target. As the TCL was increased from 1. 8 % to 53. 6 mm 3 as the BBB's opening volume increased from 3. 6 0. 1 to 53. 6 mm 3 was achieved, a safe and efficient BBB opening was achieved.
Source link: https://doi.org/10.1038/s41598-022-20568-y
Previous studies have shown the acoustic PCD response of MBs to a variety of acoustic conditions, but no one has investigated microbubble parameters. The onset of harmonic and broadband cavitation dose is dependent on the mechanical index, MB size, and MB concentration. These results, when microbubble size and concentration are combined into a gas volume fraction, are likely to coincide with similar onset and peak; these findings can help guide the planning and monitoring of MB+ FUS therapeutic procedures.
Source link: https://doi.org/10.3390/pharmaceutics14091925
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