Drop Size Distributions

Dechelette, A.; Babinsky, Erin; Sojka, Paul E.

doi:10.1007/978-1-4419-7264-4_23

Cited by 11 publications

(12 citation statements)

References 25 publications

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“…Unsteady fluid fragmentation is ubiquitous and important for a wide range of industrial processes [1,2], health applications [3][4][5][6] or pathogen dispersal in agriculture [7]. Fluid fragmentation generates numerous droplets that can travel over large distances and disperse their biological and chemical payloads.…”

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confidence: 99%

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Universal Rim Thickness in Unsteady Sheet Fragmentation

et al. 2018

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Unsteady fragmentation of a fluid bulk into droplets is important for epidemiology as it governs the transport of pathogens from sneezes and coughs, or from contaminated crops in agriculture. It is also ubiquitous in industrial processes such as paint, coating, and combustion. Unsteady fragmentation is distinct from steady fragmentation on which most theoretical efforts have been focused thus far. We address this gap by studying a canonical unsteady fragmentation process: the breakup from a drop impact on a finite surface where the drop fluid is transferred to a free expanding sheet of time-varying properties and bounded by a rim of time-varying thickness. The continuous rim destabilization selects the final spray droplets, yet this process remains poorly understood. We combine theory with advanced image analysis to study the unsteady rim destabilization. We show that, at all times, the rim thickness is governed by a local instantaneous Bond number equal to unity, defined with the instantaneous, local, unsteady rim acceleration. This criterion is found to be robust and universal for a family of unsteady inviscid fluid sheet fragmentation phenomena, from impacts of drops on various surface geometries to impacts on films. We discuss under which viscous and viscoelastic conditions the criterion continues to govern the unsteady rim thickness.

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confidence: 99%

“…Fluid fragmentation generates numerous droplets that can travel over large distances and disperse their biological and chemical payloads. Prior work focused on characterizing the droplet size distribution as a function of the breakup geometry and fluid properties [2,8,9]. Theoretical insights focused on steady fragmentation, such as Savart sheets [9][10][11].…”

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confidence: 99%

Universal Rim Thickness in Unsteady Sheet Fragmentation

et al. 2018

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“…One important metric of a fragmentation process is the final droplet size distribution, and understanding the role of material properties (e.g., fluid viscosity and relaxation time) on the polydispersity of such distributions is of crucial importance [3,4].…”

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Ligament Mediated Fragmentation of Viscoelastic Liquids

Keshavarz

Houze²,

Moore³

et al. 2016

Phys. Rev. Lett.

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The breakup and atomization of complex fluids can be markedly different than the analogous processes in a simple Newtonian fluid. Atomization of paint, combustion of fuels containing antimisting agents, as well as physiological processes such as sneezing are common examples in which the atomized liquid contains synthetic or biological macromolecules that result in viscoelastic fluid characteristics. Here, we investigate the ligament-mediated fragmentation dynamics of viscoelastic fluids in three different canonical flows. The size distributions measured in each viscoelastic fragmentation process show a systematic broadening from the Newtonian solvent. In each case, the droplet sizes are well described by Gamma distributions which correspond to a fragmentation-coalescence scenario. We use a prototypical axial step strain experiment together with high-speed video imaging to show that this broadening results from the pronounced change in the corrugated shape of viscoelastic ligaments as they separate from the liquid core. These corrugations saturate in amplitude and the measured distributions for viscoelastic liquids in each process are given by a universal probability density function, corresponding to a Gamma distribution with n min ¼ 4. The breadth of this size distribution for viscoelastic filaments is shown to be constrained by a geometrical limit which can not be exceeded in ligament-mediated fragmentation phenomena.

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“…In the past, there have been many attempts to predict mean droplet diameters [3][4][5][6] and their distributions [7][8][9][10][11][12][13] . Regarding the estimation methods for mean diameters, empirical correlations are proposed for various types of nozzles 3,4 .…”

Section: Introductionmentioning

confidence: 99%

“…Thus, it is difficult to calculate droplet diameters only by theoretical analysis when the shape of the injector is modified or the properties of the working liquid are changed. About the droplet size distributions, empirical distribution functions are proposed [7][8][9] . Their applicable ranges are inevitably restricted to the already measured data.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Prediction of Droplet Diameters Based on Energy Conservation Law

Inoue¹,

Watanabe²,

Himeno³

et al. 2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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A theoretical model is proposed and validated for calculating droplet diameters and size distributions. The model is derived based on the energy conservation law including the surface free energy and the Laplace pressure. Under several hypotheses, the law derives an equation indicating that atomization results from kinetic energy loss. Thus, once the amount of loss is determined, the droplet diameter is able to be calculated without the use of experimental parameters. When the effects of ambient gas are negligible, injection velocity profiles of liquid jets are the essential cause of the reduction of kinetic energy. The minimum Sauter mean diameter produced by liquid sheet atomization is inversely proportional to the injection Weber number when the injection velocity profiles are laminar or turbulent. A non-dimensional distribution function is also derived from the mean diameter model and Nukiyama-Tanasawa's function. The new estimation methods are favorably validated by comparing with corresponding mean diameters and the size distributions, which are experimentally measured under atmospheric pressure. NomenclatureC  = energy source [J/s] d = droplet diameter [m] m n d = mean diameter [m] d 10 = arithmetic mean diameter [m] d 32 = Sauter mean diameter (SMD) [m] D = nozzle diameter [m] e = internal energy [J/kg] f N (d) = distribution function [1/m] g = gravity acceleration [m/s 2 ] h = half of liquid sheet thickness [m] k ． = kinetic energy flux [J/s] L = distance from impingement point [m] m ． = mass flow rate [kg/s] m ． L = total mass flow rate from a nozzle [kg/s] N ． = rate of droplet production [1/s] p = static pressure [Pa] Q  = heat flux [J/s] r = radial distance [m] 1/ R = averaged curvature [1/m] Re = Reynolds number( V e D/) [ -] S  = flux of surface area of liquid [m 2 /s] u = velocity [m/s] V e = averaged velocity [m/s] 2 We = Weber number(V e 2 D/) [ -]   = coefficient of viscosity [Pa･s]   = density [kg/m 3 ]   = surface tension coefficient [N/m]    = atomization efficiency [ -]  k = ratio of kinetic energy loss [ -] Subscripts G / L = gas / liquid i, j, k, l = number of each jet/drop in/out = inlet/outlet uni = uniform injection velocity profile

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Drop Size Distributions

Cited by 11 publications

References 25 publications

Universal Rim Thickness in Unsteady Sheet Fragmentation

Universal Rim Thickness in Unsteady Sheet Fragmentation

Ligament Mediated Fragmentation of Viscoelastic Liquids

Theoretical Prediction of Droplet Diameters Based on Energy Conservation Law

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