Droplet breakup in airflow with strong shear effect

Xu, Zhikun; Wang, Tianyou; Che, Zhizhao

doi:10.1017/jfm.2022.326

Cited by 24 publications

(11 citation statements)

References 58 publications

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“…The lognormal distribution has been widely used to describe the fragment size in the spray community [38][39][40]. However, it is remarkable to observe the validity of this theory in the breakup of liquid droplets in a turbulent TC flow.…”

Section: Results (A) the Dispersed Phase Statistics In Dilute Turbule...mentioning

confidence: 99%

Recent developments of turbulent emulsions in Taylor–Couette flow

Wang

Huisman

et al. 2023

Phil. Trans. R. Soc. A.

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Emulsions are common in many natural and industrial settings. Recently, much attention has been paid to understanding the dynamics of turbulent emulsions. This paper reviews some recent studies of emulsions in turbulent Taylor–Couette flow, mainly focusing on the statistics of the dispersed phase and the global momentum transport of the system. We first study the size distribution and the breakup mechanism of the dispersed droplets for turbulent emulsions with a low volume-fraction (dilute) of the dispersed phase. For systems with a high volume-fraction (dense) of the dispersed phase, we address the detailed response of the global transport (effective viscosity) of the turbulent emulsion and its connection to the droplet statistics. Finally, we will discuss catastrophic phase inversions, which can happen when the volume-fraction of the dispersed phase exceeds a critical value during dynamic emulsification. We end the manuscript with a summary and an outlook including some open questions for future research. This article is part of the theme issue ‘Taylor–Couette and related flows on the centennial of Taylor’s seminal Philosophical Transactions paper (part 1)’.

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Section: Results (A) the Dispersed Phase Statistics In Dilute Turbule...mentioning

confidence: 99%

Recent developments of turbulent emulsions in Taylor–Couette flow

Wang

Huisman

et al. 2023

Phil. Trans. R. Soc. A.

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“…2020; Jackiw & Ashgriz 2021; Kirar et al. 2022; Xu, Wang & Che 2022), there have been very few studies on the size distribution of satellite droplets after fragmentation of a large droplet (Srivastava 1971; Villermaux & Bossa 2009; Gao et al. 2022; Jackiw & Ashgriz 2022).…”

Section: Introductionmentioning

confidence: 99%

“…Subsequently, Marshall & Palmer (1948) established a relationship that correlates the average diameter of raindrops with rainfall rate, which has been used in rainfall modelling even today (Villermaux & Bossa 2009). Although several researchers have studied the droplet fragmentation phenomenon due to its importance in a variety of industrial applications, such as combustion, surface coating, pharmaceutical manufacturing and disease transmission modelling (Marmottant & Villermaux 2004;Villermaux 2007;Soni et al 2020;Jackiw & Ashgriz 2021;Kirar et al 2022;Xu, Wang & Che 2022), there have been very few studies on the size distribution of satellite droplets after fragmentation of a large droplet (Srivastava 1971;Villermaux & Bossa 2009;Gao et al 2022;Jackiw & Ashgriz 2022). Moreover, to our knowledge, no one has previously investigated the droplet size distribution under swirl airstream, even though such a situation is frequently encountered during rainfall (Lewellen, Lewellen & Xia 2000;Haan et al 2017) and in many industrial applications (Soni & Kolhe 2021;Candel et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Droplet size distribution in a swirl airstream using in-line holography technique

Ade

Kirar²,

Chandrala³

et al. 2023

J. Fluid Mech.

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We investigate the morphology and size distribution of satellite droplets resulting from the interaction of a freely falling water droplet with a swirling airstream of different strengths by employing shadowgraphy and deep-learning-based digital in-line holography techniques. We found that the droplet exhibits vibrational, retracting bag and normal breakup phenomena for the no swirl, low and high swirl strengths for the same aerodynamic field. In the high-swirl scenario, the disintegrations of the nodes, rim and bag-film contribute to the number mean diameter, resulting in smaller satellite droplets. In contrast, in the low-swirl case, the breakup of the rim and nodes only contributes to the size distribution, resulting in larger droplets. The temporal variation of the Sauter mean diameter reveals that for a given aerodynamic force, a high swirl strength produces more surface area and surface energy than a low swirl strength. The theoretical prediction of the number-mean probability density of tiny satellite droplets under swirl conditions agrees with experimental data. However, for the low swirl, the predictions differ from the experimental results, particularly due to the presence of large satellite droplets. Our results reveal that the volume-weighted droplet size distribution exhibits two (bi-modal) and three (multi-model) peaks for low and high swirl strengths, respectively. The analytical model that takes into account various mechanisms, such as the nodes, rim and bag breakups, accurately predicts the shape and characteristic sizes of each mode for the case of high swirl strength.

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“…Droplet fragmentation and resulting child droplet size distribution (DSD) are important for a wide range of industrial applications, such as combustion, surface coating, pharmaceutical production, disease transmission modelling and artificial rain technology, to name a few (Villermaux 2007; Raut et al. 2021; Xu, Wang & Che 2022). They are also essential for understanding natural phenomena such as clouds and rainfall (Villermaux & Bossa 2009; Villermaux & Eloi 2011).…”

Section: Introductionmentioning

confidence: 99%

Size distribution of a drop undergoing breakup at moderate Weber numbers

2023

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The size distribution of child droplets resulting from a dual-bag fragmentation of a water drop is investigated using shadowgraphy and digital in-line holography techniques. It is observed that parent drop fragmentation contributes to the atomisation of tiny child droplets, whereas core drop disintegration predominantly results in larger fragments. Despite the complexity associated with dual-bag fragmentation, we demonstrate that it exhibits a bi-modal size distribution. In contrast, the single-bag breakup undergoes a tri-modal size distribution. We employ the analytical model developed by Jackiw & Ashgriz (J. Fluid Mech., vol. 940, 2022, A17) for dual-bag fragmentation that convincingly predicts the experimentally observed droplet volume probability density. We also estimate the temporal evolution of child droplet production in order to quantitatively illustrate the decomposition into initial and core breakups. Furthermore, we confirm that the analytical model adequately predicts the droplet size distribution for a range of Weber numbers.

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Droplet breakup in airflow with strong shear effect

Cited by 24 publications

References 58 publications

Recent developments of turbulent emulsions in Taylor–Couette flow

Recent developments of turbulent emulsions in Taylor–Couette flow

Droplet size distribution in a swirl airstream using in-line holography technique

Size distribution of a drop undergoing breakup at moderate Weber numbers

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