Modelling spray impingement using linear stability theories for droplet shattering

Yoon, Sam S.; DesJardin, Paul E.

doi:10.1002/fld.1069

Cited by 14 publications

(5 citation statements)

References 33 publications

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“…However, it does not begin to address the secondary distribution of the spray, such as the number of secondary droplets produced in the splash, and their individual velocities and trajectories from the impaction site. Such post-shatter information is not considered in the current study, but relevant models have been published in Yoon and Desjardin (2006) and Dorr et al (2014).…”

Section: Shatter Criterionmentioning

confidence: 99%

“…There are few studies which model the post-shatter behaviour deterministically (number, velocity and trajectory of secondary drops), although it can be achieved to some extent through energy balance models very similar to those used for spread and bounce (Yoon and Desjardin, 2006). Alternatively, empirically-based statistical models may be used, such as those by Saint-Jean et al (2004); Gigot et al (2014) for the rain-splash dispersal of pathogens.…”

Section: Introductionmentioning

confidence: 99%

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Impaction of spray droplets on leaves: influence of formulation and leaf character on shatter, bounce and adhesion

et al. 2015

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This paper combines experimental data with simple mathematical models to investigate the influence of spray formulation type and leaf character (wettability) on shatter, bounce and adhesion of droplets impacting with cotton, rice and wheat leaves. Impaction criteria that allow for different angles of the leaf surface and the droplet impact trajectory are presented; their predictions are based on whether combinations of droplet size and velocity lie above or below bounce and shatter boundaries. In the experimental component, real leaves are used, with all their inherent natural variability. Further, commercial agricultural spray nozzles are employed, resulting in a range of droplet characteristics. Given this natural variability, there is broad agreement between the data and predictions. As predicted, the shatter of droplets was found to increase as droplet size and velocity increased, and the surface became harder to wet. Bouncing of droplets occurred most frequently on hard to wet surfaces with high surface tension mixtures. On the other hand, a number of small droplets with low impact velocity were observed to bounce when predicted to lie well within the adhering regime. We believe this discrepancy between the predic-G.J. Dorr (joint first author), tions and experimental data could be due to air layer effects that were not taken into account in the current bounce equations. Other discrepancies between experiment and theory are thought to be due to the current assumption of a dry impact surface, whereas, in practice, the leaf surfaces became increasingly covered with fluid throughout the spray test runs. arXiv:1506.04258v1 [physics.flu-dyn]

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Section: Shatter Criterionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impaction of spray droplets on leaves: influence of formulation and leaf character on shatter, bounce and adhesion

et al. 2015

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“…Additionally, Allen (1975Allen ( , 1988 applied the Rayleigh-Taylor (R-T) instability theory to demonstrate that splashing was one of the products of instability formation. Recent research, however, has shown that Kelvin-Helmholtz (K-H) instability, which is caused by the shear stress between two fluids moving in parallel at a relative velocity, provides a better explanation of splashing than R-T instability theory because it considers the exchange of momentum between the gas underneath and the droplet as the latter is about to impact the solid surface (Kim et al, 2000;Yoon and DesJardin, 2006;Yoon et al, 2007). In this context, Xu (2007) discovered that as the ambient pressure drops to 0.17 atm, splashing could not be observed.…”

Section: Rementioning

confidence: 99%

“…2: Effect of We on splashing. Left column, water droplet with We = 695; and right column, ethanol droplet with We = 1870(Yoon and DesJardin, 2006).…”

mentioning

confidence: 99%

Splashing Phenomena During Liquid Droplet Impact

Liu

Yoon

et al. 2010

Atomiz Spr

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Splashing is a phenomenon often observed during liquid droplet impact onto a solid surface. The threshold of splashing is known to be related to droplet size, impact velocity, and physical properties of the liquid, but the mechanisms that initiate splashing are not understood completely. In accordance with the Kelvin-Helmholtz (K-H) instability analysis, recent studies have shown that ambient gas density has a significant effect on the threshold and trajectory of splashing. In this study, the effects of droplet velocity, impact angle, and ambient gas pressure (or density) on the threshold of splashing and the motion of the ambient gas surrounding the droplet were examined. Experimental observations of splashing were carried out with a droplet of 1.7 mm in diameter, while varying droplet velocity, impact angle, and ambient pressure. An empirical correlation was derived using our and other published data to determine the threshold of splashing based on the aforementioned parameters. Also, a numerical simulation using the volume of fluid method was carried out to calculate the gas velocities surrounding the droplet during impact. The results of this model gave supportive evidence that K-H instability is a suitable instability theory that helps explain the splash phenomenon with consideration of the gas motion surrounding the droplet.

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“…The dynamic morphological changes of a single droplet impacting a solid wall can be divided into six categories [153], as shown in Figure 11. In the critical stage of the impact process, forced energy and mass are conserved [154]. Roisman et al found that when a single droplet has a retreat after impact and diffusion, the process is determined by the interaction between the free edge and the internal liquid layer and the force exerted by the wall on the edge [155].…”

Section: Factors Affecting Environmental Humidity In Facility Agricul...mentioning

confidence: 99%

Research Status and Prospects on the Construction Methods of Temperature and Humidity Environmental Models in Arbor Tree Cuttage

Wang,

Liu,

Xie

et al. 2023

Agronomy

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The environmental temperature and humidity are crucial factors for the normal growth and development of arbor tree cuttings by altering their hormone levels and influencing their physiological activities. Developing a temperature and humidity environmental model for arbor tree cuttings serves as a key technique to improve the adjustment performance of environmental parameters in facility agriculture systems and enhance the rooting rate of cuttings. This paper provides a comprehensive summary of current research on the inherent characteristics of cuttings and the factors influencing environmental temperature and humidity. It explores the mechanisms of interaction between the inherent characteristics of cuttings and the factors influencing environmental temperature and humidity. This paper investigates the interactive relationships among the factors affecting environmental temperature and humidity. It analyzes methods to improve the efficiency of constructing temperature and humidity environmental models for arbor tree cuttings. To enhance the transferability of the environmental model, the necessary physiological activities under the influence of plant hormones are generalized as common physiological traits in the growth and development of cuttings. In addition, this paper explores the factors influencing the air and substrate temperature and the humidity in facility agriculture systems as well as two types of facilities for controlling environmental temperature and humidity. Furthermore, it reviews the research progress in environmental models from both mechanistic and data-driven perspectives. This paper provides a comparative analysis of the characteristics associated with these two model categories. Building upon this, the paper summarizes and discusses methods employed in constructing temperature and humidity environmental models for arbor tree cuttings. In addition, it also anticipates the application of deep learning techniques in the construction of temperature and humidity environmental models for arbor cuttings, including utilizing machine vision technology to monitor their growth status. Finally, it proposes suggestions for building physiological models of fruit tree-like arbor cuttings at different growth stages. To enhance the transferability of environmental models, the integration of physiological models of cuttings, environmental models, and control system performance are suggested to create an environmental identification model. This paper aims to achieve control of the common physiological activities of cuttings.

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Modelling spray impingement using linear stability theories for droplet shattering

Cited by 14 publications

References 33 publications

Impaction of spray droplets on leaves: influence of formulation and leaf character on shatter, bounce and adhesion

Impaction of spray droplets on leaves: influence of formulation and leaf character on shatter, bounce and adhesion

Splashing Phenomena During Liquid Droplet Impact

Research Status and Prospects on the Construction Methods of Temperature and Humidity Environmental Models in Arbor Tree Cuttage

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