Double Contact During Drop Impact on a Solid Under Reduced Air Pressure

Li, Erqiang; Langley, Kenneth R.; Tian, Yuansi; Hicks, Peter D.; Thoroddsen, Sigurður T.

doi:10.1103/physrevlett.119.214502

Cited by 48 publications

(42 citation statements)

References 35 publications

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“…Here we observe no jetting for the axisymmetric case of one inner drop. Also for two drops the drops appear to be too close to the centreline; perhaps the edge of the central air disc trapped under the drop (Li & Thoroddsen 2015;Hendrix et al 2016;Li et al 2017) reaches too close to the location of the inner droplet dimple (see § 3.4). For N = 3 some infrequent jetting is observed, while for N 4 most realizations have strong jetting.…”

Section: Jetting Speedmentioning

confidence: 99%

Fine radial jetting during the impact of compound drops

Zhang

Thoroddsen

2019

J. Fluid Mech.

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Section: Jetting Speedmentioning

confidence: 99%

Fine radial jetting during the impact of compound drops

Zhang

Thoroddsen

2019

J. Fluid Mech.

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“…Several recent studies including , Kolinski et al (2012), Kolinski et al (2014) and de Ruiter et al (2015) argue that the droplet begins to spread on an ultra-thin gas layer before it touches down, with Liu et al (2015) showing that by draining the gas from under an impacting drop using a porous substrate, splashing can be inhibited. Recent progress on the early dynamics and advances in ultra-high speed imaging experiments have lead to renewed insight into the motion inside the gas region under the impact and its consequences for touchdown (see , , Langley et al (2017) and Li et al (2017)). Once touchdown has occurred, the gas layer retracts into a central gas bubble, which can have detrimental effects in, for example, printing applications, see amongst others Thoroddsen et al (2005), Hicks & Purvis (2010) and Hicks & Purvis (2013).…”

Section: Introductionmentioning

confidence: 99%

Early-time jet formation in liquid–liquid impact problems: theory and simulations

Cimpeanu

Moore²

2018

J. Fluid Mech.

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We perform a thorough qualitative and quantitative comparison of theoretical predictions and direct numerical simulations for the two-dimensional, vertical impact of two droplets of the same fluid. In particular, we show that the theoretical predictions for the location and velocity of the jet root are excellent in the early stages of the impact, while the predicted jet velocity and thickness profiles are also in good agreement with the computations before the jet begins to bend. By neglecting the role of the surrounding gas both before and after impact, we are able to use Wagner theory to describe the early-time structure of the impact. We derive the model for general droplet velocities and radii, which encompasses a wide range of impact scenarios from the symmetric impact of identical drops to liquid drops impacting a deep pool. The leading-order solution is sufficient to predict the curve along which the root of the high-speed jet travels. After moving into a frame fixed in this curve, we are able to derive the zero-gravity shallow-water equations governing the leading-order thickness and velocity of the jet. Our numerical simulations are performed in the open-source software Gerris, which allows for the level of local grid refinement necessary for a problem with such a wide variety of length scales. The numerical simulations incorporate more of the physics of the problem, in particular the surrounding gas, the fluid viscosities, gravity and surface tension. We compare the computed and predicted solutions for a range of droplet radii and velocities, finding excellent agreement in the early stage. In light of these successful comparisons, we discuss the tangible benefits of using Wagner theory to confidently track properties such as the jet-root location, jet thickness and jet velocity in future studies of splash jet/ejecta evolution.

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“…The inertial dynamics are unable to account for the effects of ambient pressure [21,24]. Recent studies [18,[25][26][27][28][29][30][31] do not provide confirmation about the potential formation of an air film underneath the lamella tip before the splash initiation. A model based on the lamella aerodynamics [20] appears to be suitable for applications to a variety of conditions [20][21][22][32][33][34][35] and will be used in the present study.…”

mentioning

confidence: 99%

Droplet Splashing on an Inclined Surface

et al. 2019

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Oblique droplet impacts onto a smooth surface at various inclination angles and at different ambient gas pressures were investigated using high-speed photography. It was found that the droplet splash can be entirely suppressed either by increasing the inclination angle or by reducing the ambient pressure. Variations of the threshold angle required for the splash suppression as a function of the impact velocity were determined, as well as the threshold pressure as a function of the inclination angle and the impact velocity. The threshold pressure increases monotonically as the inclination angle increases for small enough impact velocities but varies in a nonmonotonic manner for high enough impact velocities. Modifications of the existing splash model permit the theoretical determination of the splash threshold conditions that agree well with the experimental observations. It is shown that it is the velocity of the lamella tip that determines the splash onset.

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Double Contact During Drop Impact on a Solid Under Reduced Air Pressure

Cited by 48 publications

References 35 publications

Fine radial jetting during the impact of compound drops

Fine radial jetting during the impact of compound drops

Early-time jet formation in liquid–liquid impact problems: theory and simulations

Droplet Splashing on an Inclined Surface

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