Dynamics of the cavity and the surface film for impingements of single drops on liquid films of various thicknesses

Hinsberg, Nils Paul van; Budaklı, Mete; Göhler, Sebastian; Berberović, Edin; Roisman, Ilia V.; Gambaryan‐Roisman, Tatiana; Stephan, Peter

doi:10.1016/j.jcis.2010.06.015

Cited by 54 publications

(29 citation statements)

References 21 publications

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“…19 b), where the cavity collapse time is dramatically increased for higher Weber numbers, although it has essentially no influence on the dimensionless cavity formation time. All these observations are consistent with the conclusions in van Hinsberg et al 10 The centerline sub-cavity film thickness has also been analyzed as a ratio to initial film thickness (h/h 0 ). Effects of variations of h 0 * and Weber number on this ratio are shown in Figs.…”

Section: B Centerline Sub-cavity Liquid Film Thickness Resultssupporting

confidence: 89%

“…10 This phenomenon is observed in the present data. The effects of varying the Weber number and initial film thickness on the resulting centerline sub-cavity film thickness histories have been analyzed.…”

Section: B Centerline Sub-cavity Liquid Film Thickness Resultssupporting

confidence: 88%

“…However, in this preliminary work the initial droplet parameters and dimensionless film thicknesses (h 0 * =h 0 /d) were not based on measured spray conditions for a particular spray nozzle. Similar optical instrumentation was used by van Hinsberg et al 10 to profile the time-dependent sub-cavity liquid film thickness along the impact centerline of single impinging droplets. Their results found the centerline sub-cavity film thickness to be dependent upon the initial dimensionless liquid film thickness and the impinging droplet Reynolds number, but this thickness reached a constant value at high droplet Weber and Froude numbers.…”

Section: Figure 2 Single Drop Impingement Into An Unheated Initial Lmentioning

confidence: 99%

“…Their results found the centerline sub-cavity film thickness to be dependent upon the initial dimensionless liquid film thickness and the impinging droplet Reynolds number, but this thickness reached a constant value at high droplet Weber and Froude numbers. 10 The purpose of the current work is to improve and expand upon the initial study by Hillen et al 7 by computing the sub-cavity volume for the range of dimensionless parameters for realistic spray conditions. Table 1 summarizes the droplet sizes and liquid film thicknesses generated by a spray impinging onto a surface measured from previous works.…”

Section: Figure 2 Single Drop Impingement Into An Unheated Initial Lmentioning

confidence: 99%

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Droplet impact time histories for a range of Weber numbers and liquid film thicknesses for spray cooling application

Hillen

Taylor

Menchini

et al. 2013

43rd Fluid Dynamics Conference

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Spray cooling is a topic of current interest for its ability to uniformly remove high levels of waste heat for densely packed microelectronics. A Monte-Carlo (MC) spray cooling simulation model is under development that is based on empirical data to be a cost effective design tool that will predict accurate heat fluxes based on nozzle conditions and heater geometry. This work reports spray and single drop experiments with the goal of computing the volume beneath a drop impact cavity (sub-cavity volume) created by a single impinging droplet on an initial liquid layer. A relevant test plan for the single drop experiments in terms of We and Re numbers was created through utilization of Phase Doppler Anemometry to characterize a water spray generated by a nozzle of interest for varying flow conditions. Liquid thickness profiles of the sub-cavity formed by a single impinging drop onto a range of initial liquid film thicknesses were measured versus time via a non-contact optical thickness sensor. Time dependent sub-cavity volumes were computed by integrating these sub-cavity liquid film thickness profiles measured radially outward from the impact centerline. It is found that higher We and lower h 0 * result in a more radially uniform sub-cavity surface contour versus time, except for regions near the outer bottom cavity radius, where the liquid film was thinner. The sub-cavity volume was found to be nearly constant for a majority of the cavity lifetime and increased with We and h 0 * . These results will be incorporated in future work into the MC model to improve its predictive capability. Nomenclatured = Drop diameter Greek Letters D = Arithmetic mean droplet diameter ρ = Density D 32 = Sauter mean droplet diameter η = Index of refraction Fr = Froude number = μ = Dynamic viscosity h = Liquid film thickness σ = Surface tension R = Radial location τ = Dimensionless time (t•V axial /d) Re = Reynolds number = Superscripts T = Temperature * = Dimensionless parameter t = Time Subscripts V = Arithmetic mean velocity 0 = Initial condition Vol = Sub-cavity volume axial = Axial velocity component We = Weber number = c = Cavity z = Axial standoff distance from the nozzle tip r = Radial velocity component s = Spray

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Section: B Centerline Sub-cavity Liquid Film Thickness Resultssupporting

confidence: 89%

Section: B Centerline Sub-cavity Liquid Film Thickness Resultssupporting

confidence: 88%

Section: Figure 2 Single Drop Impingement Into An Unheated Initial Lmentioning

confidence: 99%

Section: Figure 2 Single Drop Impingement Into An Unheated Initial Lmentioning

confidence: 99%

See 2 more Smart Citations

Droplet impact time histories for a range of Weber numbers and liquid film thicknesses for spray cooling application

Hillen

Taylor

Menchini

et al. 2013

43rd Fluid Dynamics Conference

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“…It has been recently shown that the expression for the evolution of the lamella thickness in the form h ∼ t −2 , obtained in Yarin & Weiss (1995) from the remote inviscid solution, agrees very well with experimental and numerical data (Bakshi, Roisman & Tropea 2007;Roisman et al 2009;van Hinsberg et al 2010). Therefore, the flow in the lamella generated by high Reynolds drop collision can be described well by (4.12) with A = 1.…”

Section: Thickness Of the Lamellasupporting

confidence: 73%

Binary collisions of drops of immiscible liquids

et al. 2011

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International audienceThis experimental and theoretical study is devoted to the investigation of head-on collisions of two drops of immiscible liquids. In the experiments, pairs of drops are made to collide at well-defined kinetic and geometric conditions. The sizes and relative velocity of the colliding drops close to the point of impact are measured by means of image processing. The deformed states after the impact, their evolution with time, and their stability are studied by visualization. The theory considers the dynamics of the rim formed at the edge of a radially spreading lamella due to capillary forces at the free surfaces of the lamella and at the liquid/liquid interface. The equations of the rim formation and motion are obtained from the volume, mass and momentum balance equations which account for the inertial, viscous and capillary effects. The theory predicts the evolution of the main geometrical parameters of the liquid mass formed by the drop collision: thickness of the lamella, diameter, and size of the rim cross-section. The theoretical predictions agree well with the experimental data, although no adjustable parameters are used in the model

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Liquid Film Sculpture via Droplet Impacting on Microstructured Heterowettable Surfaces

Chu

Wen

et al. 2022

Adv Funct Materials

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Liquid manipulation plays an increasingly critical role in daily life and future technological processes. Although intensive attention is paid on controlling droplets, how to manipulate the behavior of larger scale liquid film still remains mysterious. Here, a droplet-impact-induced liquid film sculpture strategy is demonstrated on a microstructured heterowettable surface that can precisely sculpt a liquid film into any graphic pattern. The fundamental principles of the liquid film sculpture are elucidate and a phase diagram is drawn to distinguish three liquid film states upon droplet impacting including dewetting, rupture, and nonrupture. To precisely guide the film sculpture, the microstructured heterowettable surface is designed so that water film will naturally rupture at the top of the microstructure after the droplet impact and subsequently dewet into desired pattern. Liquid film sculpture is accompanied by self-propulsion and high construction speed, both of which are preferred in no-spray printing, painting, cleaning, and drawing, inspiring future artistic and engineering applications.

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Dynamics of the cavity and the surface film for impingements of single drops on liquid films of various thicknesses

Cited by 54 publications

References 21 publications

Droplet impact time histories for a range of Weber numbers and liquid film thicknesses for spray cooling application

Droplet impact time histories for a range of Weber numbers and liquid film thicknesses for spray cooling application

Binary collisions of drops of immiscible liquids

Liquid Film Sculpture via Droplet Impacting on Microstructured Heterowettable Surfaces

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