Review of mass and momentum interactions during drop impact on a liquid film

Liang, Gangtao; Mudawar, Issam

doi:10.1016/j.ijheatmasstransfer.2016.05.062

Cited by 230 publications

(107 citation statements)

References 157 publications

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“…However, Figure 5b shows that, when stripes on these walls are fully covered with lube oil, the adhered ratio remains almost unchanged, which means that, when the wall film is thicker than Sa or Sq, the influence of roughness on the droplet splash decreases or has no effect. A similar conclusion for a single water droplet impacting is provided in Reference [38].…”

Section: Development Of Adhering Fuel Mass Ratiosupporting

confidence: 77%

Experimental Investigation on Effect of Wall Roughness and Lubricant Film on the Adhered Fuel Film of N-Butanol-Diesel Blends after Spray Impingement

et al. 2018

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Abstract:The effect of wall roughness with different lubricant film thicknesses on the characteristics of adhered fuel films of diesel-n-butanol blending fuels after spray impingement has been investigated. Four steel plates with different types of roughness (root mean square height-Sq) that were coated with different lubricant film thicknesses (h l ) were used as impinged walls. The experimental conditions included dry walls (h l = 0), semi-wetted walls (SWW) with different thin oil films (0 < h l /Sq < 1), and fully wetted walls (FWW) with a thick lubricant film (h l > Sq). The results indicate that the adhered fuel mass ratio (ε) of blended fuel with 25% n-butanol (B25) was higher than that of blended fuel with 15% n-butanol (B15) under the same conditions. ε increased with an increase in Sq on the dry walls, but, under SWW conditions, it decreased with an increase in oil film thickness. The fuel film morphology was almost unaffected by the change in Sq, but the results implied that the roughness parameter-Skewness (Ssk) exerted a greater impact. The mean thickness h a and accumulated diameter D l of the adhered fuel film increased with an increase in h l , but, under FWW conditions, the effect of the roughness on the adhered film's features was insignificant.

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Section: Development Of Adhering Fuel Mass Ratiosupporting

confidence: 77%

Experimental Investigation on Effect of Wall Roughness and Lubricant Film on the Adhered Fuel Film of N-Butanol-Diesel Blends after Spray Impingement

et al. 2018

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“…2(f). If the flat surface is wet, the film presence interferes with the evolution of the phenomenon (Cossali et al, 1997;Wang and Chen, 2000;Rioboo et al, 2003;Yarin, 2006;and Liang and Mudawar, 2016). The impingement outcomes in this case can be rebounding, deposition, prompt splash, and crown splash, which are similar to those described for impact on dry surfaces.…”

Section: Introductionmentioning

confidence: 64%

“…As it is described by the review of Liang and Mudawar (2016), there is no complete consensus on the evolution of the crown base for collisions of droplets on flat surfaces, but generally it grows as a function of time with an exponent around 0.5 or less. In the present investigation, while the measurements were not time resolved due to the small scales involved, it was found that the film length was more or less invariant at the commencement of instability.…”

Section: Onset Of Instability On the Crown Rimmentioning

confidence: 99%

“…In the present investigation, while the measurements were not time resolved due to the small scales involved, it was found that the film length was more or less invariant at the commencement of instability. As such, it can be inferred that there may be a correlation between the perturbation of the crown at its base due to the length of the travelled distance and the commencement of instability which may be taken into account when considering the development of the Rayleigh Plateau instability, which is considered the dominant instability mechanism (Liang and Mudawar, 2016).…”

Section: Onset Of Instability On the Crown Rimmentioning

confidence: 99%

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Collisions of droplets on spherical particles

Charalampous

Hardalupas

2017

Physics of Fluids

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Head-on collisions between droplets and spherical particles are examined for water droplets in the diameter range between 170 μm and 280 μm and spherical particles in the diameter range between 500 μm and 2000 μm. The droplet velocities range between 6 m/s and 11 m/s, while the spherical particles are fixed in space. The Weber and Ohnesorge numbers and ratio of droplet to particle diameter were between 92 < We < 1015, 0.0070 < Oh < 0.0089, and 0.09 < Ω < 0.55, respectively. The droplet-particle collisions are first quantified in terms of the outcome. In addition to the conventional deposition and splashing regimes, a regime is observed in the intermediate region, where the droplet forms a stable crown, which does not breakup but propagates along the particle surface and passes around the particle. This regime is prevalent when the droplets collide on small particles. The characteristics of the collision at the onset of rim instability are also described in terms of the location of the film on the particle surface and the orientation and length of the ejected crown. Proper orthogonal decomposition identified that the first 2 modes are enough to capture the overall morphology of the crown at the splashing threshold.

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“…This active research resulted in a lot of progresses with still many open questions, especially about splash mechanism which could involve sub-micronic effects. For an updated state-of-the-art, the reader is strongly encouraged to read the insightful reviews proposed by Josserand and Thoroddsen [3] and Liang and Mudawar [4]. The outcome of a drop impact can be classified in three regimes, mainly depending on the impact velocity.…”

Section: Introductionmentioning

confidence: 99%

Toward direct numerical simulation of high speed droplet impact

et al. 2019

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When a liquid drop impacts a solid surface or a liquid film, several outcomes are possible. In particular, splashing phenomena can exhibit complex behaviors, like the formation of very thin crowns and emission of small droplets. Underlying mechanisms are hard to elucidate, partly due to the difficulty for current experimental devices to access to the very small length scales involved. Here, we use direct numerical simulation to explore low and high velocity drop impact phenomena. We show that classical incompressible two-phase methods can be sufficient to address low energy impacts and take into account wetting phenomena. However, dedicated robust and conservative methods are needed to simulate splashing phenomenon at higher velocities. In our test cases, we show that an impact on a thick liquid film exhibits thick crown formation and delayed splashing. On a dry wall, on the other hand, splashing phenomenon can be difficult to reproduce even with high velocity impacts. We show however how a higher value of the surrounding air density may trigger splashing. The presence of a even very thin liquid film on the wall strongly modifies impact outcome, forcing the ejection of a thin crown and subsequent secondary droplet emission.

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Review of mass and momentum interactions during drop impact on a liquid film

Cited by 230 publications

References 157 publications

Experimental Investigation on Effect of Wall Roughness and Lubricant Film on the Adhered Fuel Film of N-Butanol-Diesel Blends after Spray Impingement

Experimental Investigation on Effect of Wall Roughness and Lubricant Film on the Adhered Fuel Film of N-Butanol-Diesel Blends after Spray Impingement

Collisions of droplets on spherical particles

Toward direct numerical simulation of high speed droplet impact

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