Experimental study of the impact of an ink-jet printed droplet on a solid substrate

Dam, D.B. van; Clerc, Christophe Le

doi:10.1063/1.1773551

Cited by 319 publications

(213 citation statements)

References 27 publications

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“…III. Equation (53) shows good agreement with the trends shown and the limited measured bubble volumes in the experiments for droplet impact with a solid, 3,4 with the volume of the gas bubble trapped increasing with bubble radius and decreasing with impact speed. 18 Very limited experimental results exist which allow comparison of the bubble volume with the liquid layer depth.…”

Section: Trapped Bubble Sizesupporting

confidence: 73%

“…2 In addition to bubbles trapped by air cushioning between a droplet and a liquid layer, experimental studies have also shown that gas bubbles can be created as the result of air cushioning during droplet impact with a rigid surface. 3,4 In air-cushioned droplet impact experiments, in addition to the large central bubble, much smaller bubbles have also been seen at a greater radius from the center of the impact in a phenomena called Mesler entrainment. 5,6 This is inferred to be the result of capillary interactions between the droplet and liquid layer free-surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Air cushioning in droplet impacts with liquid layers and other droplets

Hicks

Purvis

2011

Physics of Fluids

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Air cushioning of a high-speed liquid droplet impact with a finite-depth liquid layer sitting upon a rigid impermeable base is investigated. The evolution of the droplet and liquid-layer free-surfaces is studied alongside the pressure in the gas film dividing the two. The model predicts gas bubbles are trapped between the liquid free-surfaces as the droplet approaches impact. The key balance in the model occurs when the depth of the liquid layer equals the horizontal extent of interactions between the droplet and the gas film. For liquid layer depths significantly less than this a shallow liquid limit is investigated, which ultimately tends towards the air-cushioning behavior seen in droplet impact with a solid surface. Conversely, for liquid layer depths much deeper than this, the rigid base does not affect the air-cushioning of the droplet. The influence of compressibility is discussed and the relevant parameter regime for an incompressible model is identified. The size of the trapped gas bubble as a function of the liquid layer depth is investigated. The deep water model is extended to consider binary droplet collisions. Again, the model predicts gas bubbles will be trapped as the result of air cushioning in high-speed binary droplet impacts

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Section: Trapped Bubble Sizesupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Air cushioning in droplet impacts with liquid layers and other droplets

Hicks

Purvis

2011

Physics of Fluids

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“…Eventually the decelerated droplet free-surface directly below the centre of the droplet is overtaken by the surrounding free surface, with the pressure profiles similarly bifurcating to produce maxima where the separation between free surface and substrate are least. Touchdown then goes on to occur around a ring some horizontal distance away from the point directly below the centre of an air bubble, leading to a trapped pocket of gas, which subsequently may evolve to form a bubble, as observed in experiments [4,6,38]. In a vacuum, the initial touchdown would occur at time t = 0.…”

Section: Gas Behaviour In the Substratementioning

confidence: 95%

Gas-cushioned droplet impacts with a thin layer of porous media

Hicks

Purvis

2015

J Eng Math

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The pre-impact gas cushioning behaviour of a droplet approaching touchdown onto a thin layer of porous substrate is investigated. Although the model is applicable to droplet impacts with any porous substrate of limited height, a thin layer of porous medium is used as an idealized approximation of a regular array of pillars, which are frequently used to produced superhydrophobic and superhydrophilic textured surface. Bubble entrainment is predicted across a range of permeabilities and substrate heights, as a result of a gas pressure build-up in the viscous-gas squeeze film decelerating the droplet free-surface immediately below the centre of the droplet. For a droplet of water of radius 1 mm and impact approach speed 0.5 m s −1 the change from a flat rigid impermeable plate to a porous substrate of height 5 µm and permeability 2.5 µm 2 reduces the initial horizontal extent of the trapped air pocket by 48%, as the porous substrate provides additional pathways through which the gas can escape. Further increases in either the substrate permeability or substrate height can entirely eliminate the formation of a trapped gas pocket in the initial touchdown phase, with the droplet then initially hitting the top surface of the porous media at a single point.Droplet impacts with a porous substrate are qualitatively compared to droplet impacts with a rough impermeable surface, which provides a second approximation for a textured surface. This indicates that only small pillars can be successfully modelled by the porous media approximation. The effect of surface tension on gas-cushioned droplet impacts with porous substrates is also investigated. In contrast to the numerical predictions of a droplet free-surface above flat plate, when a porous substrate is included the droplet free-surface touches down in finite time. Mathematically this is due to the regularization of the parabolic degeneracy associated with the small gas-film-height limit the gas squeeze film equation, by non-zero substrate permeability and height, and physically suggests that the level of surface roughness is a critical parameter in determining the initial touchdown characteristics.

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“…Most studies on low-speed droplet impact focus on the spreading and splashing of droplets. 6,7 Surprisingly, the field between high-speed and low-speed droplet impact ͑i.e., velocities between 20 m and 150 m/s͒ did not receive much attention in the past.…”

Section: Introductionmentioning

confidence: 99%

Removal of biofilms by impinging water droplets

Cense

Dongen

Gottenbos

et al. 2006

Journal of Applied Physics

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The process of impinging water droplets on Streptococcus mutans biofilms was studied experimentally and numerically. Droplets were experimentally produced by natural breakup of a cylindrical liquid jet. Droplet diameter and velocity were varied between 20 and 200 m and between 20 and 100 m/s, respectively. The resulting erosion process of the biofilm was determined experimentally with high-speed recording techniques and a quantitative relationship between the removal rate, droplet size, and velocity was determined. The shear stress and the pressure on the surface during droplet impact were determined by numerical simulations, and a qualitative agreement between the experiment and the simulation was obtained. Furthermore, it was shown that the stresses on the surface are strongly reduced when a water film is present.

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Experimental study of the impact of an ink-jet printed droplet on a solid substrate

Cited by 319 publications

References 27 publications

Air cushioning in droplet impacts with liquid layers and other droplets

Air cushioning in droplet impacts with liquid layers and other droplets

Gas-cushioned droplet impacts with a thin layer of porous media

Removal of biofilms by impinging water droplets

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