Drop formation dynamics of constant low-viscosity, elastic fluids

Cooper-White, Justin J.; Fagan, J.E.; Tirtaatmadja, V.; Lester, Daniel; Boger, David V.

doi:10.1016/s0377-0257(02)00084-8

Cited by 125 publications

(108 citation statements)

References 51 publications

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“…The fluid was fed from a syringe pump at a rate of 73.8 ml/min. This is the same rate as that used by Cooper-White et al 35 in their drop formation study of similar fluids. Several drops of fluid were allowed to form to ensure a constant liquid flowrate prior to the images of the drop being taken for analysis.…”

Section: B Image Capture and Measurement Of Drop Formation Dynamicssupporting

confidence: 60%

“…However, a significant result of the work of Amarouchene et al 34 is the realisation that as the drop approaches the Newtonian pinch region (as indicated by a rapid reduction in the minimum drop radius), the fluid exceeds a critical extension rate prior to the formation of a viscoelastic filament connecting the droplet to the fluid above. This critical extension rate, which can be determined from the rapid change in the slope of the radius-time plot, is much higher than the rate of subsequent filament elongation and is the dominant source of polymer extension, as also pointed out by Cooper-White et al 35 It is this rapid increase in the extension rate immediately prior to the pinch point which causes the stretching of the polymer molecules in solution and the large increase in the polymer elastic stress. This elastic stress then resists the capillary pressure, inhibiting the primary drop from pinching-off.…”

Section: Introductionmentioning

confidence: 74%

“…Clasen et al 33 found good agreement of their 1D numerical simulation with experimental results for high viscosity viscoelastic fluids. Amarouchene et al 34 and Cooper-White et al 35 studied drop formation from a nozzle under gravity of low viscosity, elastic fluids, while Mun et al 36 , Christanti and Walker 37 studied the drop breakup under forced jetting. Cooper-White et al 35 and Christanti and Walker 37 studied dilute, low viscosity polymer solutions of varying molecular weights and found that the relaxation times obtained from measurements of the rates of thinning of the primary filament were much larger than the Zimm relaxation times calculated from the known concentration and molecular weight of the polymer in agreement with Bazilevskii et al 30 Cooper-White et al 35 also found the final length of the filament at detachment and the time of break-off was proportional to the relaxation time of the solutions.…”

Section: Introductionmentioning

confidence: 99%

“…Amarouchene et al 34 and Cooper-White et al 35 studied drop formation from a nozzle under gravity of low viscosity, elastic fluids, while Mun et al 36 , Christanti and Walker 37 studied the drop breakup under forced jetting. Cooper-White et al 35 and Christanti and Walker 37 studied dilute, low viscosity polymer solutions of varying molecular weights and found that the relaxation times obtained from measurements of the rates of thinning of the primary filament were much larger than the Zimm relaxation times calculated from the known concentration and molecular weight of the polymer in agreement with Bazilevskii et al 30 Cooper-White et al 35 also found the final length of the filament at detachment and the time of break-off was proportional to the relaxation time of the solutions. Amarouchene et al 34 investigated two high molecular weight polymers in aqueous solutions over a range of concentrations and found the effective relaxation times obtained from the rates of filament thinning to be dependent on the concentrations of the polymer in solution, even in the dilute regime.…”

Section: Introductionmentioning

confidence: 99%

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Drop formation and breakup of low viscosity elastic fluids: Effects of molecular weight and concentration

2006

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The dynamics of drop formation and pinch-off have been investigated for a series of low viscosity elastic fluids possessing similar shear viscosities, but differing substantially in elastic properties. On initial approach to the pinch region, the viscoelastic fluids all exhibit the same global necking behavior that is observed for a Newtonian fluid of equivalent shear viscosity. For these low viscosity dilute polymer solutions, inertial and capillary forces form the dominant balance in this potential flow regime, with the viscous force being negligible. The approach to the pinch point, which corresponds to the point of rupture for a Newtonian fluid, is extremely rapid in such solutions, with the sudden increase in curvature producing very large extension rates at this location. In this region the polymer molecules are significantly extended, causing a localized increase in the elastic stresses, which grow to balance the capillary pressure. This prevents the necked fluid from breaking off, as would occur in the equivalent Newtonian fluid. Alternatively, a cylindrical filament forms in which elastic stresses and capillary pressure balance, and the radius decreases exponentially with time. A (0+1)-dimensional finitely extensible nonlinear elastic dumbbell theory incorporating inertial, capillary, and elastic stresses is able to capture the basic features of the experimental observations. Before the critical “pinch time” tp, an inertial-capillary balance leads to the expected 2∕3-power scaling of the minimum radius with time: Rmin∼(tp−t)2∕3. However, the diverging deformation rate results in large molecular deformations and rapid crossover to an elastocapillary balance for times t>tp. In this region, the filament radius decreases exponentially with time Rmin∼exp[(tp−t)∕λ1], where λ1 is the characteristic time constant of the polymer molecules. Measurements of the relaxation times of polyethylene oxide solutions of varying concentrations and molecular weights obtained from high speed imaging of the rate of change of filament radius are significantly higher than the relaxation times estimated from Rouse-Zimm theory, even though the solutions are within the dilute concentration region as determined using intrinsic viscosity measurements. The effective relaxation times exhibit the expected scaling with molecular weight but with an additional dependence on the concentration of the polymer in solution. This is consistent with the expectation that the polymer molecules are in fact highly extended during the approach to the pinch region (i.e., prior to the elastocapillary filament thinning regime) and subsequently as the filament is formed they are further extended by filament stretching at a constant rate until full extension of the polymer coil is achieved. In this highly extended state, intermolecular interactions become significant, producing relaxation times far above theoretical predictions for dilute polymer solutions under equilibrium conditions.

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Section: B Image Capture and Measurement Of Drop Formation Dynamicssupporting

confidence: 60%

Section: Introductionmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Drop formation and breakup of low viscosity elastic fluids: Effects of molecular weight and concentration

2006

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“…Iterated instabilities have been predicted numerically and observed experimentally in viscous fluid threads, 22 but they do not lead to the formation of periodic structures such as beads-on-a-string. The initial elastic recoil and the formation of a secondary drop during pinchoff of a polymeric droplet have been documented by Cooper-White et al 23 but gravitational acceleration prohibits development of an iterated instability. In the present Letter, we demonstrate experimentally the phenomenon of iterated instability for the first time in a viscoelastic fluid thread undergoing capillary thinning.…”

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confidence: 89%

Iterated stretching and multiple beads-on-a-string phenomena in dilute solutions of highly extensible flexible polymers

2005

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A new instrument for dynamic helical squeeze flow which superposes oscillatory shear and oscillatory squeeze flow Rev. Sci. Instrum. 83, 085105 (2012) The effects of hydrodynamic interaction and inertia in determining the high-frequency dynamic modulus of a viscoelastic fluid with two-point passive microrheology Phys. Fluids 24, 073103 (2012) MHD free convection flow of a visco-elastic (Kuvshiniski type) dusty gas through a semi infinite plate moving with velocity decreasing exponentially with time and radiative heat transfer AIP Advances 1, 022132 (2011) Transitional flow of a non-Newtonian fluid in a pipe: Experimental evidence of weak turbulence induced by shearthinning behavior Phys. Fluids 22, 101701 (2010) Effects of viscoelasticity on the probability density functions in turbulent channel flow

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Inkjet Printing of Polymers: State of the Art and Future Developments

Gans

Duineveld

Schubert³

2004

Advanced Materials

1,739

1,199

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Inkjet printing is considered to be a key technology in the field of defined polymer deposition. This article provides an introduction to inkjet printing technology and a short overview of the available instrumentation. Examples of polymer inkjet printing are given, including the manufacturing of multicolor polymer light‐emitting diode displays, polymer electronics, three‐dimensional printing, and oral dosage forms for controlled drug release. Special emphasis is placed upon the utilized polymers and conditions, such as polymer structure, molar mass, solvents, and concentration. Studies on viscoelastic fluid jets and the formation of viscoelastic droplets under gravity indicate that strain hardening is the key parameter that determines the inkjet printability of polymer solutions.

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Drop formation dynamics of constant low-viscosity, elastic fluids

Cited by 125 publications

References 51 publications

Drop formation and breakup of low viscosity elastic fluids: Effects of molecular weight and concentration

Drop formation and breakup of low viscosity elastic fluids: Effects of molecular weight and concentration

Iterated stretching and multiple beads-on-a-string phenomena in dilute solutions of highly extensible flexible polymers

Inkjet Printing of Polymers: State of the Art and Future Developments

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