“…5 (b)), making them easier to be detected experimentally. In addition, numerical investigations have also demonstrated that the ADV threshold determined by the bubble growth behavior obviously increases with the ultrasound frequency increasing [27] , [28] , which is consistent with the experimental data for ADV threshold [15] , [16] . Fig.…”
Section: Resultssupporting
confidence: 85%
“…Numerous experiments have been carried out to investigate the ADV process and determine the ADV threshold, nevertheless, it exhibited a large difference among them, probably due to the experimental inconsistencies and the sensitivity of ADV threshold to multiple parameters [15] , [16] , [17] , [18] , [19] . Alternatively, theoretical prediction of ADV threshold has also been performed via investigating bubble growth in the PFC droplet [25] , [26] , [27] , [28] . However, note that a small vapor bubble nucleus was assumed to be existed prior to the bubble growth, and it has demonstrated that the bubble growth and the predicted ADV threshold strongly depend on the initial radius of the bubble nucleus [25] , [28] .…”
Section: Introductionmentioning
confidence: 99%
“…Alternatively, theoretical prediction of ADV threshold has also been performed via investigating bubble growth in the PFC droplet [25] , [26] , [27] , [28] . However, note that a small vapor bubble nucleus was assumed to be existed prior to the bubble growth, and it has demonstrated that the bubble growth and the predicted ADV threshold strongly depend on the initial radius of the bubble nucleus [25] , [28] . The formation of the initial vapor bubble nucleus (i.e., bubble nucleation) is a prerequisite for ADV and it also needs a threshold, so that the ADV threshold is co-determined by the thresholds of initial bubble nucleation and subsequent bubble growth.…”
Section: Introductionmentioning
confidence: 99%
“…Classical nucleation theory (CNT), the most commonly-used theory of nucleation, has been used to predict the ADV threshold of PFP microdroplets via homogeneous or heterogeneous nucleation [23] , [29] , [30] . Especially, Miles et al first combined the CNT with the superharmonic focusing effect of the microdroplets to predict the ADV nucleation threshold of PFP microdroplets [30] , but this mechanism may disappear for small droplets of 2 μm or less [28] . Moreover, compared to the PFP microdroplet, the nanodroplet always experiences a much larger Laplace pressure and significantly elevates the liquid pressure in the nanodroplet, resulting in a greater impact on the initial ADV nucleation that occurs in the pressurized PFP core [23] .…”
Highlights
Initial bubble nucleation in a metastable PFP nanodroplet during ADV was described.
The modified CNT combined the phase-change thermodynamics of PFP.
The thermodynamics was exactly predicted by the Redlich–Kwong equation of state.
The modified CNT eliminated the intrinsic limitations of the CNT.
Nanodroplet properties exerted strong influences on the ADV nucleation threshold.
“…5 (b)), making them easier to be detected experimentally. In addition, numerical investigations have also demonstrated that the ADV threshold determined by the bubble growth behavior obviously increases with the ultrasound frequency increasing [27] , [28] , which is consistent with the experimental data for ADV threshold [15] , [16] . Fig.…”
Section: Resultssupporting
confidence: 85%
“…Numerous experiments have been carried out to investigate the ADV process and determine the ADV threshold, nevertheless, it exhibited a large difference among them, probably due to the experimental inconsistencies and the sensitivity of ADV threshold to multiple parameters [15] , [16] , [17] , [18] , [19] . Alternatively, theoretical prediction of ADV threshold has also been performed via investigating bubble growth in the PFC droplet [25] , [26] , [27] , [28] . However, note that a small vapor bubble nucleus was assumed to be existed prior to the bubble growth, and it has demonstrated that the bubble growth and the predicted ADV threshold strongly depend on the initial radius of the bubble nucleus [25] , [28] .…”
Section: Introductionmentioning
confidence: 99%
“…Alternatively, theoretical prediction of ADV threshold has also been performed via investigating bubble growth in the PFC droplet [25] , [26] , [27] , [28] . However, note that a small vapor bubble nucleus was assumed to be existed prior to the bubble growth, and it has demonstrated that the bubble growth and the predicted ADV threshold strongly depend on the initial radius of the bubble nucleus [25] , [28] . The formation of the initial vapor bubble nucleus (i.e., bubble nucleation) is a prerequisite for ADV and it also needs a threshold, so that the ADV threshold is co-determined by the thresholds of initial bubble nucleation and subsequent bubble growth.…”
Section: Introductionmentioning
confidence: 99%
“…Classical nucleation theory (CNT), the most commonly-used theory of nucleation, has been used to predict the ADV threshold of PFP microdroplets via homogeneous or heterogeneous nucleation [23] , [29] , [30] . Especially, Miles et al first combined the CNT with the superharmonic focusing effect of the microdroplets to predict the ADV nucleation threshold of PFP microdroplets [30] , but this mechanism may disappear for small droplets of 2 μm or less [28] . Moreover, compared to the PFP microdroplet, the nanodroplet always experiences a much larger Laplace pressure and significantly elevates the liquid pressure in the nanodroplet, resulting in a greater impact on the initial ADV nucleation that occurs in the pressurized PFP core [23] .…”
Highlights
Initial bubble nucleation in a metastable PFP nanodroplet during ADV was described.
The modified CNT combined the phase-change thermodynamics of PFP.
The thermodynamics was exactly predicted by the Redlich–Kwong equation of state.
The modified CNT eliminated the intrinsic limitations of the CNT.
Nanodroplet properties exerted strong influences on the ADV nucleation threshold.
“…Nanodroplets are vaporized into microbubbles when the amplitude of ultrasonic pulses exceeds a certain intensity called ADV threshold. An ultrasound-triggered bubble, which oscillates with alternating the positive and negative pressure portion of the pulses, can rapidly collapse with or without rebounds depending on the acoustic amplitude [3] , [4] , [5] , [6] , [7] . During the rapid bubble collapse, the liquid region near the bubble is also compressed to a high pressure above the critical pressure, resulting in a shock wave emission [8] .…”
In acoustic droplet vaporization (ADV), a cavitated bubble grows and collapses depending on the pressure amplitude of the acoustic pulse. During the bubble collapse, the surrounding liquid is compressed to high pressure, and liquid compressibility can have a significant impact on bubble behavior and ADV threshold. In this work, a one-dimensional numerical model considering liquid compressibility is presented for ADV of a volatile microdroplet, extending our previous Rayleigh-Plesset based model [Ultrason. Chem. 71 (2021) 105361]. The numerical results for bubble motion and liquid energy change in ADV show that the liquid compressibility highly inhibits bubble growth during bubble collapse and rebound, especially under high acoustic frequency conditions. The liquid compressibility effect on the ADV threshold is quantified with varying acoustic frequencies and amplitudes.
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