Validation and application of a novel elongational device for polymer solutions

Stelter, M.; Brenn, Günter; Yarin, Alexander L.; Singh, R. P.; Durst, F.

doi:10.1122/1.551102

Cited by 179 publications

(189 citation statements)

References 24 publications

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“…Direct measurement of this rate of decay thus enables quantitative determination of the fluid relaxation time. [10][11][12][13] Recent theoretical analyses and numerical simulations of one-dimensional slender filament models have shown that the profile R͑z , t͒ evolves in a self-similar manner; however, the precise dynamics depend on the relative magnitudes of the inertial, viscous, elastic, and capillary terms in the governing equations. 14,15 Ultimately, finite extensibility of the molecules truncates the exponential stress growth, and the thread is then expected to thin linearly in time towards a breakup event with a general form R͑t͒ϳ͑ / E ͒͑t c − t͒.…”

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confidence: 99%

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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confidence: 99%

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

2005

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“…The Reynolds number on the abscissa is defined as Re qd h l c _ a =g 0 , where q is the fluid density, g 0 is the zero shear viscosity (in case of Newtonian liquids g 0 ¼ l), l c _ is the local increment in velocity at the throat arising from the constriction, and d h ¼ 2hw c =ðh þ w c Þ ¼ 267 lm is the hydraulic diameter defined at the throat of the contraction. The true pressure drop across the contraction DP c is related to the measured pressure difference between sensors 2 and 3 by the expression 56 DP c ¼ DP 23 …”

Section: Evroc Measurementsmentioning

confidence: 99%

“…17,18 For lower viscosity systems, an instrument based on the analysis of capillary thinning and breakup of liquid filaments was first introduced by Entov and coworkers 19 and later developed extensively by McKinley and coworkers and others. [20][21][22][23][24] Capillary Breakup Extensional Rheometry (CaBER) has become a common method to study the elongational rheology of a wide range of dilute complex fluids. [25][26][27][28] However, conventional measurements from CaBER can be affected by fluid inertia and the dynamics of the end-plates.…”

Section: Introductionmentioning

confidence: 99%

Micro-scale extensional rheometry using hyperbolic converging/diverging channels and jet breakup

Keshavarz

McKinley

2016

Biomicrofluidics

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Understanding the elongational rheology of dilute polymer solutions plays an important role in many biological and industrial applications ranging from microfluidic lab-on-a-chip diagnostics to phenomena such as fuel atomization and combustion. Making quantitative measurements of the extensional viscosity for dilute viscoelastic fluids is a long-standing challenge and it motivates developments in microfluidic fabrication techniques and high speed/strobe imaging of millifluidic capillary phenomena in order to develop new classes of instruments. In this paper, we study the elongational rheology of a family of dilute polymeric solutions in two devices: first, steady pressure-driven flow through a hyperbolic microfluidic contraction/expansion and, second, the capillary driven breakup of a thin filament formed from a small diameter jet (D j $ Oð100 lmÞ). The small length scale of the device allows very large deformation rates to be achieved. Our results show that in certain limits of low viscosity and elasticity, jet breakup studies offer significant advantages over the hyperbolic channel measurements despite the more complex implementation. Using our results, together with scaling estimates of the competing viscous, elastic, inertial and capillary timescales that control the dynamics, we construct a dimensionless map or nomogram summarizing the operating space for each instrument. Published by AIP Publishing. [http://dx

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“…These instabilities refer to the growth of satellite fluid droplet(s) connected to either of or both the fluid hemispheres through the filament. The formation of so called 'bead-on-string' structures in the capillary thinning of filaments and jets has been investigated extensively (Chang et al 1999;Stelter et al 2000;Li and Fontelos 2003;Clasen et al 2006a). 'Bead-onstring' flow instabilities in uniaxial extensional flows have been reported to be primarily caused by either (1) inertia or (2) elasticity.…”

Section: Introductionmentioning

confidence: 99%

Extensional rheometry of cellulose ether solutions: flow instability

Vadodaria

English

2015

Cellulose

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Capillary breakup extensional rheometry of semi-dilute hydroxyethyl cellulose (HEC) solutions was performed under several step-stretch conditions. The resulting parameters, i.e. terminal steady state extensional viscosity (g E ) and the timescale for viscoelastic stress growth, commonly referred to as the extensional relaxation time (k E ) were found to be sensitive to the step-stretch conditions. The k E decreased with increasing step-strain as opposed to the g E . Prior to the filament break-up, a 'bead-onstring' instability was observed close to the mid-plane. It is believed that this instability originated from the accumulation of viscoelastic stresses near the filament neck leading to the 'elastic recoil' of the extended polymer chains. The reasons for this belief are discussed in detail with the perspective of the past literature. Such type of flow instability has been reported for the first time for a cellulosic system. Various dimensionless numbers were plotted for the HEC solutions and compared with those obtained from past studies for various biopolymers as well as synthetic polymers.

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Validation and application of a novel elongational device for polymer solutions

Cited by 179 publications

References 24 publications

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

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

Micro-scale extensional rheometry using hyperbolic converging/diverging channels and jet breakup

Extensional rheometry of cellulose ether solutions: flow instability

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