Liquid bridge length scale based nondimensional groups for mapping transitions between regimes in capillary break-up experiments

Verbeke, Karel; Formenti, Susanna; Briatico‐Vangosa, Francesco; Mitrias, Christos; Reddy, Naveen Krishna; Anderson, Patrick Patrick; Clasen, Christian

doi:10.1103/physrevfluids.5.051901

Cited by 11 publications

(12 citation statements)

References 31 publications

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“…What are the conditions dynamics must meet to exhibit an intermediate size-dependent inertio-capillary 1 2 regime instead of directly following the purely inertio-capillary 2 3 regime? For pinching dynamics, the distinction between the 1 2 and 2 3 regimes is usually connected to the viscosity ratio between the inner and outer fluid [61]. For instance, bubbles of air in water will exhibit the 1 2 regime, whereas water drops will exhibit the 2 3 regime [16].…”

Section: The Ohnesorge Unitsmentioning

confidence: 99%

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Spreading, pinching, and coalescence: the Ohnesorge units

Fardin¹,

Hautefeuille²,

Sharma³

2021

Preprint

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Understanding the kinematics and dynamics of spreading, pinching, and coalescence of drops is critically important for a diverse range of applications involving spraying, printing, coating, dispensing, emulsification, and atomization. Hence experimental studies visualize and characterize the increase in size over time for drops spreading over substrates, or liquid bridges between coalescing drops, or the decrease in the radius of pinching necks during drop formation. Even for Newtonian fluids, the interplay of inertial, viscous, and capillary stresses can lead to a number of scaling laws, with three limiting self-similar cases: visco-inertial (VI), visco-capillary (VC) and inertio-capillary (IC). Though experiments are presented as examples of the methods of dimensional analysis, the lack of precise values or estimates for pre-factors, transitions, and scaling exponents presents difficulties for quantitative analysis and material characterization. In this contribution, we reanalyze and summarize an elaborate set of landmark published experimental studies on a wide range of Newtonian fluids. We show that moving beyond VI, VC, and IC units in favor of intrinsic timescale and lengthscale determined by all three material properties (viscosity, surface tension and density), creates a complementary system that we call the Ohnesorge units. We find that in spite of large differences in topological features, timescales, and material properties, the analysis of spreading, pinching and coalescing drops in the Ohnesorge units results in a remarkable collapse of the experimental datasets, highlighting the shared and universal features displayed in such flows.

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Section: The Ohnesorge Unitsmentioning

confidence: 99%

“…In general, ratios of the material properties of the inner and outer fluids can have an impact on the dynamics. This issue has been investigated for spreading [64,65], coalescence [50,65] and pinching [61] and we hope to be able to include these studies in the future.…”

Section: Departures From Ohnesorge's Unitsmentioning

confidence: 99%

Spreading, pinching, and coalescence: the Ohnesorge units

Fardin¹,

Hautefeuille²,

Sharma³

2021

Preprint

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“…While custom-built CaBER instruments have introduced chambers with better sealing for temperature control 34 , 35 , these studies did not utilize the chambers for controlling evaporation. Previous work by Sousa and coworkers 33 , 36 incorporates true environmental control by suspending the aqueous samples in an oil bath, but this method introduces an oil–water interface which further affects liquid bridge thinning 37 and is unsuitable for samples miscible in oil. Similar to CaBER, a sealed micro-filament rheometer has been used to measure volatile pressure-sensitive adhesive fluids and a 1D Newtonian model was developed to predict filament thinning in the presence of volatile solvent 14 .…”

Section: Introductionmentioning

confidence: 99%

Evaporation-controlled dripping-onto-substrate (DoS) extensional rheology of viscoelastic polymer solutions

Robertson

Calabrese

2022

Sci Rep

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Extensional flow properties of polymer solutions in volatile solvents govern many industrially-relevant coating processes, but existing instrumentation lacks the environment necessary to control evaporation. To mitigate evaporation during dripping-onto-substrate (DoS) extensional rheology measurements, we developed a chamber to enclose the sample in an environment saturated with solvent vapor. We validated the evaporation-controlled DoS device by measuring a model high molecular weight polyethylene oxide (PEO) in various organic solvents both inside and outside of the chamber. Evaporation substantially increased the extensional relaxation time $$\lambda _{E}$$ λ E for PEO in volatile solvents like dichloromethane and chloroform. PEO/chloroform solutions displayed an over 20-fold increase in $$\lambda _{E}$$ λ E due to the formation of an evaporation-induced surface film; evaporation studies confirmed surface features and skin formation reminiscent of buckling instabilities commonly observed in drying polymer solutions. Finally, the relaxation times of semi-dilute PEO/chloroform solutions were measured with environmental control, where $$\lambda _{E}$$ λ E scaled with concentration by the exponent $$m=0.62$$ m = 0.62 . These measurements validate the evaporation-controlled DoS environment, and confirm that chloroform is a good solvent for PEO, with a Flory exponent of $$\nu =0.54$$ ν = 0.54 . Our results are the first to control evaporation during DoS extensional rheology, and provide guidelines establishing when environmental control is necessary to obtain accurate rheological parameters.

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“…An extensive literature exists on transitions of pinch-off regimes (Li & Sprittles 2016; Verbeke et al. 2020), and a good overview can be found in Eggers (2005). The third objective of this work then is to determine the role of the pinch-off stage in the drawing dynamics.…”

Section: Introductionmentioning

confidence: 99%