Droplet impact on a thin fluid layer

Howison, Sam; Ockendon, J. R.; Oliver, James M.; Purvis, Richard; Smith, F. T.

doi:10.1017/s0022112005006282

Cited by 71 publications

(77 citation statements)

References 13 publications

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“…Asymptotic theories of droplet impact predict that the contributions to the splash jet from the layer and the droplet are equal due to symmetry for non-dimensional times t ( (H=R) 2=3 after impact, 23 with the jet exactly dividing the gap between droplet and layer due to symmetry. In this regime the small droplet penetration depth means the effect of the bottom of the liquid layer is not felt.…”

Section: Discussionmentioning

confidence: 99%

“…Asymptotic analyses for solid-deep water impacts, 10,19,20 solid-shallow water impact, 21 and droplet-liquid layer impact 22,23 show liquid jet initiation close to the point of impact which has the potential to evolve into the characteristic splash seen in many impacts. However, in models which neglect the air phase, the liquid remains completely stationary or in uniform motion, right until the point of initial touchdown, in contradiction to the air-cushioning experiments and analysis.…”

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: Discussionmentioning

confidence: 99%

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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“…All these methods are based on the theory of complex variables and reduce the problem to one or two integral equations, which are then solved by a numerical method. The solution of this kind of problem with emphasis on blunt bodies was also considered in the framework of matched asymptotic expansions in recent studies [12][13][14][15][16]. In this method, the order of magnitude of the deadrise angle between the body and the x-axis is used as a small parameter of expansion.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric impact between liquid and solid wedges

Semënov

2013

Proc. R. Soc. A.

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The hydrodynamic problem of impact between a solid wedge and a liquid wedge is analysed. The liquid is assumed to be ideal and incompressible; gravity and surface tension effects are ignored. The flow generated by the impact is assumed to be irrotational and therefore can be described by the velocity potential theory. The solution procedure is based on the analytical derivation of the complexvelocity potential in a parameter plane and the function mapping conformally the parameter plane onto the similarity plane. The mapping function is found as a combination of the derivatives of the complex potential in the similarity and parameter planes, through the integral equations for mixed and homogeneous boundary-value problems in terms of the velocity modulus and the velocity angle with the fluid boundary, together with the dynamic and kinematic boundary conditions. These equations are solved through a numerical method. The procedure is first verified through comparisons with some known results. Simulations are then made for a variety of cases, and detailed results are presented in terms of the free surface shape, streamlines, pressure distribution on the wetted solid surface, and contact angles between the free surface and the body surface.

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“…Part of their analysis uses the theory of Wagner [17] for describing the position and nature of the overturning free surface near the jet root, theory which is explained further in chapter 9 of Faltinsen [8]. The splash jets made by droplet impact onto a liquid layer are treated by Howison et al [10].…”

Section: Introductionmentioning

confidence: 99%

A theory for the impact of a wave breaking onto a permeable barrier with jet generation

Cooker

2012

J Eng Math

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Abstract. We model a water wave impact onto a porous breakwater. The breakwater surface is modelled as a thin barrier composed of solid matter pierced by channels through which water can flow freely. The water in the wave is modelled as a finite-length volume of inviscid, incompressible fluid in quasi-onedimensional flow during its impact and flow through a typical hole in the barrier. The fluid volume moves at normal incidence to the barrier. After the initial impact the wave water starts to slow down as it passes through holes in the barrier. Each hole is the source of a free jet along whose length the fluid velocity and width vary in such a way as to conserve volume and momentum at zero pressure. We find there are two types of flow, depending on the porosity, β, of the barrier. If β : 0 ≤ β < 0.5774 then the barrier is a strong impediment to the flow, in that the fluid velocity tends to zero as time tends to infinity. But if β : 0.5774 ≤ β ≤ 1 then the barrier only temporarily holds up the flow, and the decelerating wave water passes through in a finite time. We report results for the velocity and impact pressure due to the incident wave water, and for the evolving shape of the jet, with examples from both types of impact. We account for the impulse on the barrier and the conserved kinetic energy of the flow. Consideration of small β gives insight into the sudden changes in flow and the high pressures that occur when a wave impacts a nearly impermeable seawall.

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Droplet impact on a thin fluid layer

Cited by 71 publications

References 13 publications

Air cushioning in droplet impacts with liquid layers and other droplets

Air cushioning in droplet impacts with liquid layers and other droplets

Asymmetric impact between liquid and solid wedges

A theory for the impact of a wave breaking onto a permeable barrier with jet generation

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