Curved surface effect on high-speed droplet impingement

Wu, Wangxia; Liu, Qingquan; Wang, Bing

doi:10.1017/jfm.2020.926

Cited by 20 publications

(11 citation statements)

References 78 publications

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“…higher than ) as studied by Kondo & Ando (2016) and Wu et al. (2018 b , 2021). Assuming homogeneous nucleation, Ando et al.…”

Section: Resultsmentioning

confidence: 68%

“…2016) or, as we already mentioned, a drop (Obreschkow et al. 2006; Gonzalez-Avila & Ohl 2016; Kondo & Ando 2016; Kyriazis, Koukouvinis & Gavaises 2018; Wu, Xiang & Wang 2018 b ; Wu, Liu & Wang 2021; Biasiori-Poulanges & Schmidmayer 2023). Laser cavitation in some of these configurations was lately applied in studies involving x-ray holography or x-ray diffraction to investigate the propagation of shock waves in liquids (Stan et al.…”

Section: Introductionmentioning

confidence: 78%

“…If the negative pressure amplitude of the reflected wave is below the cavitation threshold of the liquid, a trail of bubbles is nucleated after the wave passage. This effect is commonly observed upon wave reflection on the free boundary of a flat surface (Heijnen et al 2009), nearby bubbles (Quinto-Su & Ando 2013), a liquid column (Sembian et al 2016) or, as we already mentioned, a drop (Obreschkow et al 2006;Gonzalez-Avila & Ohl 2016;Kondo & Ando 2016;Kyriazis, Koukouvinis & Gavaises 2018;Wu, Xiang & Wang 2018b;Wu, Liu & Wang 2021;Biasiori-Poulanges & Schmidmayer 2023). Laser cavitation in some of these configurations was lately applied in studies involving x-ray holography or x-ray diffraction to investigate the propagation of shock waves in liquids (Stan et al 2016;Ursescu et al 2020;Hagemann et al 2021).…”

Section: Introductionmentioning

confidence: 87%

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Bubble nucleation and jetting inside a millimetric droplet

et al. 2023

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In this work we present experiments and simulations on the nucleation and successive dynamics of laser-induced bubbles inside liquid droplets in free-fall motion, i.e. a case where the bubbles are subjected to the influence of a free boundary in all directions. Within this spherical millimetric droplet, we have investigated the nucleation of secondary bubbles induced by the rarefaction wave that is produced when the shock wave emitted by the laser-induced plasma reflects at the drop surface. Interestingly, three-dimensional clusters of cavitation bubbles are observed. Their shape is compared with the negative pressure distribution computed with a computational fluid dynamics model and allows us to estimate a cavitation threshold value. In particular, we observed that the focusing of the waves in the vicinity of the free surface can give rise to explosive cavitation events that end up in fast liquid ejections. High-speed recordings of the drop/bubble dynamics are complemented by the velocity and pressure fields simulated for the same initial conditions. The effect of the proximity of a curved free surface on the jetting dynamics of the bubbles was qualitatively assessed by classifying the cavitation events using a non-dimensional stand-off parameter ${\Upsilon\hskip -1,05em -\,}$ that depends on the drop size, the bubble maximum radius and the relative position of the bubble inside the drop. Additionally, we studied the role of the drop's curvature by implementing a structural similarity algorithm to compare cases with bubbles produced near a flat surface to the bubbles inside the drop. Interestingly, this quantitative comparison method indicated the existence of equivalent stand-off distances at which bubbles influenced by different boundaries behave in a very similar way. The oscillation of the laser-induced bubbles promotes the onset of Rayleigh–Taylor and Rayleigh–Plateau instabilities, observed on the drop's surface. This phenomenon was studied by varying the ratio of the maximum radii of the bubble and the drop. The specific mechanisms leading to the destabilisation of the droplet surface were identified.

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“…higher than ) as studied by Kondo & Ando (2016) and Wu et al. (2018 b , 2021). Assuming homogeneous nucleation, Ando et al.…”

Section: Resultsmentioning

confidence: 68%

Section: Introductionmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 87%

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Bubble nucleation and jetting inside a millimetric droplet

et al. 2023

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“…Field, Dear & Ogren (1989) and Field et al (2012) observed that, when a high-speed droplet impacts a rigid wall, convergence of reflected expansion waves could cause cavitation bubbles. The possibility of cavitation of a high-speed droplet impacting the wall was verified by Kondo & Ando (2016), Wu et al (2018) and Wu, Liu & Wang (2021b) via the numerical method. Xiang & Wang (2017) and Biasiori-Poulanges & El-Rabii (2021) expounded that the occurrence of cavitation inside the shocked water column is dependent on the incident shock wave intensity and the value of the cavitation threshold pressure.…”

Section: Introductionmentioning

confidence: 99%

Analysis of wave converging phenomena inside the shocked two-dimensional cylindrical water column

Fan

et al. 2023

J. Fluid Mech.

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Due to the curvature of the droplet surface, the propagation of transmitted waves is complex inside a droplet impacted by an incident shock wave. The wave converging phenomena inside a two-dimensional water column impacted by different curved shock waves are explored in this paper by means of theoretical ray analysis and high-resolution numerical simulations. An analytical method describing the wave structure evolution characteristics inside the shocked water column is established. Hence, the morphological pattern and focus locations of these waves are theoretically obtained. The analysis shows that both the first and the second reflected waves focus inside the water column regardless of the convergent, planar or divergent nature of the incident shock wave shape. The dimensionless distances from focusing points to the column centre are derived as ${\kappa }/{( 3\kappa -{{M}_{0}}{{f}_{s}} )}$ for the former and ${\kappa }/{( 5\kappa -{{M}_{0}}{{f}_{s}})}$ for the latter, respectively. Here, $\kappa$ , $M_0$ and $f_s$ represent the sound-speed ratio of the two phases, the incident shock wave strength and a function characterising the shock wave shape effect, respectively. Moreover, highly negative pressures due to the first reflected wave focusing and significant pressure oscillations due to the second reflected wave focusing are numerically tracked for three shapes of the incident shock. The effects of the incident shock wave intensity on the pressure variations at focus points are further studied. As the incident shock wave intensity increases, stronger negative pressure and higher pressure oscillation are induced. The converged incident shock wave can enhance the above phenomena, but the diverged one can weaken them.

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“…Multiphase flows with phase transitions and heat transfer are ubiquitous in natural and industrial processes, such as atmospheric phenomena, material and food processing, petrochemical engineering and bio-medicine, as well as life sciences (Brennen 2005; Bernaschi, Melchionna & Succi 2019; Zang et al. 2019; Wu, Liu & Wang 2021 b ). Therefore, establishing accurate, reliable and efficient models and computational strategies for predicting their flow behaviour will deepen our understanding of the fundamental and underlying physical mechanisms behind multiphase flows.…”

Section: Introductionmentioning

confidence: 99%

Discrete Boltzmann multi-scale modelling of non-equilibrium multiphase flows

Gan

Xu²,

Lai³

et al. 2022

J. Fluid Mech.

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The aim of this paper is twofold: the first aim is to formulate and validate a multi-scale discrete Boltzmann method (DBM) based on density functional kinetic theory for thermal multiphase flow systems, ranging from continuum to transition flow regime; the second aim is to present some new insights into the thermo-hydrodynamic non-equilibrium (THNE) effects in the phase separation process. Methodologically, for bulk flow, DBM includes three main pillars: (i) the determination of the fewest kinetic moment relations, which are required by the description of significant THNE effects beyond the realm of continuum fluid mechanics; (ii) the construction of an appropriate discrete equilibrium distribution function recovering all the desired kinetic moments; (iii) the detection, description, presentation and analysis of THNE based on the moments of the non-equilibrium distribution ( $f-f^{(eq)}$ ). The incorporation of appropriate additional higher-order thermodynamic kinetic moments considerably extends the DBM's capability of handling larger values of the liquid–vapour density ratio, curbing spurious currents, and ensuring mass/momentum/energy conservation. Compared with the DBM with only first-order THNE (Gan et al., Soft Matt., vol. 11 (26), 2015, pp. 5336–5345), the model retrieves kinetic moments beyond the third-order super-Burnett level, and is accurate for weak, moderate and strong THNE cases even when the local Knudsen number exceeds $1/3$ . Physically, the ending point of the linear relation between THNE and the concerned physical parameter provides a distinct criterion to identify whether the system is near or far from equilibrium. Besides, the surface tension suppresses the local THNE around the interface, but expands the THNE range and strengthens the THNE intensity away from the interface through interface smoothing and widening.

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Curved surface effect on high-speed droplet impingement

Abstract: Abstract

Cited by 20 publications

References 78 publications

Bubble nucleation and jetting inside a millimetric droplet

Bubble nucleation and jetting inside a millimetric droplet

Analysis of wave converging phenomena inside the shocked two-dimensional cylindrical water column

Discrete Boltzmann multi-scale modelling of non-equilibrium multiphase flows

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