Measurement of extensional viscosity by stretching large liquid bridges in microgravity

Berg, Simon van den; Kröger, Roland; Rath, H. J.

doi:10.1016/0377-0257(94)80075-8

Cited by 35 publications

(39 citation statements)

References 6 publications

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“…The radius R t mid ( ) at the axial midplane is either measured directly with a laser micrometer or obtained from digitized images of the entire column profile. If inertial effects and viscous stresses in the external fluid are negligible then this necked configuration is symmetric about the midplane; however, if these effects become significant, then more complex shapes arise (Berg et al 1994;Gaudet et al 1996). In a filament stretching device the imposed displacement is exponential in nature and the force exerted on one of the plates is monitored as a function of time in order to extract the extensional viscosity (Szabo, 1997).…”

Section: Problem Formulationmentioning

confidence: 99%

How to extract the Newtonian viscosity from capillary breakup measurements in a filament rheometer

McKinley¹,

Tripathi²

2000

Journal of Rheology

342

272

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Section: Problem Formulationmentioning

confidence: 99%

How to extract the Newtonian viscosity from capillary breakup measurements in a filament rheometer

McKinley¹,

Tripathi²

2000

Journal of Rheology

342

272

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“…The Oldroyd-B equation is a three parameter model that predicts a constant shear viscosity g 0 g p g s and ®rst normal stress coef®cient W 10 2g p k 1 in steady shear¯ow and a strain-rate-dependent extensional viscosity in transient uniaxial elongation (Bird, Armstrong and Hassager (1987)). Another feature of the upper-convected Jeffreys model is that for a Deborah number D b 0X5 the axial stresses in a homogeneous uniaxial elongational¯ow grow unbounded in time and a steady state value of the extensional viscosity cannot be achieved (Bird, Armstrong and Hassager (1987)).…”

Section: Constitutive Equationmentioning

confidence: 99%

“…In a laboratory this boundary motion could be achieved by having end plates that are made of a compressible sponge-like or stretched elastomeric material, for example. Berg, Kro Èger and Rath (1994) performed this experiment using an elastic diaphragm.…”

Section: Validation Case: Homogeneous Extensional Flowmentioning

confidence: 99%

“…The transient evolution of the non-Newtonian stresses for an ideal extensional¯ow (1) can be obtained analytically (Bird, Armstrong and Hassager (1987)), by integrating the Oldroyd-B equation, and expressed in dimensionless form…”

Section: Validation Case: Homogeneous Extensional Flowmentioning

confidence: 99%

“…In this work we use the generalized upper-convected Maxwell model (Bird, Armstrong and Hassager (1987)) together with an additional solvent contribution to compute the evolution of the viscoelastic stresses in the¯uid. In dimensional terms the stresses are written in terms of a Newtonian contribution T N and a polymeric contribution T NN as:…”

Section: Constitutive Equationmentioning

confidence: 99%

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Extensional deformation of non-Newtonian liquid bridges

Gaudet

McKinley

1998

Computational Mechanics

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A numerical method for simulating the extensional dynamics of elongating ®laments of non-Newtonian uids in a ®lament stretching rheometer is presented. The boundary element method, in conjunction with either the Oldroyd-B or the generalized multimode Upper-Convected Maxwell constitutive model, is used to calculate the transient evolution of the liquid interface, the applied force on the stationary end plate and the polymeric stresses. The numerical results are compared to experimental results and are in excellent agreement at low Hencky strains (Newtonian response) but provide less accurate modeling of the stress growth observed in experiments at higher strains. A comparison of different methods for measuring the apparent extensional viscosity from global measurements of the net force and the mid-point radius of the ®lament is presented. At large strains calculations show that the¯uid motion in these devices closely approximates ideal uniaxial elongation.

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Drop Deformation in Uniaxial Extensional Flow Fields in Microgravity

Berg¹,

Dreyer

Rath

1999

Chem. Eng. Technol.

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A liquid bridge stretching technique for measuring the deformation of emulsion drops in pure uniaxial extensional flow is presented. The experiments are carried out in the droptower facility of ZARM at the University of Bremen which provides microgravity conditions of about 10 ±6 g for 4.7 s.The liquid bridge is generated under microgravity and held between two plates by surface tension. The initial length and diameter of the cylindrical bridge are 30 mm. The fluid bridge is stretched exponentially to a maximum length of one meter providing a maximum Hencky strain of about 3.5. At the same time, the disk diameter is reduced exponentially from 30 to 10 mm in order to preserve the cylindrical bridge contour.The new device makes drop deformation experiments possible with emulsion drops of any density and wide-spread viscosity ratio. Thus, drop deformation experiments with a single drop or cluster of a few drops in a pure extensional flow field are possible. A result of this project is the specification of the time dependence of the deformation in relation to the capillary number describing the ratio between viscous stress and capillary pressure and to the viscosity ratio between drop and matrix fluid.

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Measurement of extensional viscosity by stretching large liquid bridges in microgravity

Cited by 35 publications

References 6 publications

How to extract the Newtonian viscosity from capillary breakup measurements in a filament rheometer

How to extract the Newtonian viscosity from capillary breakup measurements in a filament rheometer

Extensional deformation of non-Newtonian liquid bridges

Drop Deformation in Uniaxial Extensional Flow Fields in Microgravity

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