The extensional flow capillary as a new method for extensional viscosity measurement

Everage, A. E.; Ballman, R. L.

doi:10.1038/273213a0

Cited by 40 publications

(16 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Two main approaches can be identified: experiments using abrupt contractions which are easier to design and build and those using hyperbolic contractions which provide a better approximation to a uniform extension rate (Everage and Ballman, 1978). Macroscopic studies are typically restricted to viscous liquids η 1 Pa s because the extension rates O(1000 s −1 ) needed to probe the elongational behaviour of low viscosity solutions η ∼ 0.001 Pa s often result in large inertial stresses which dominate the viscous contribution to the total pressure drop across the contraction plane.…”

Section: Microfluidic Contraction Flowsmentioning

confidence: 99%

Microfluidic rheometry

Pipe¹,

McKinley²

2009

Mechanics Research Communications

230

161

View full text Add to dashboard Cite

The development and growth of microfluidics has stimulated interest in the behaviour of complex liquids in microscale geometries and provided a rich platform for rheometric investigations of non-Newtonian phenomena at small scales. Microfluidic techniques present the rheologist with new opportunities for material property measurement and this review discusses the use of microfluidic devices to measure bulk rheology in both shear and extensional flows. Capillary, stagnation and contraction flows are presented in this context and developments, limitations and future perspectives are examined.

show abstract

Section: Microfluidic Contraction Flowsmentioning

confidence: 99%

Microfluidic rheometry

Pipe¹,

McKinley²

2009

Mechanics Research Communications

230

161

View full text Add to dashboard Cite

show abstract

“…The hyperbolically-shaped contraction is unique in that it can be used to impose a nominally constant extension rate along its centerline for a given volumetric flow rate, as discussed by James (1991). It was first studied in an axisymmetric configuration by Everage & Ballman (1978), but the corresponding planar configuration, was first studied only recently by Oliveira et al (2007). These authors studied the detailed kinematics of planar hyperbolic contraction flows both experimentally and numerically for Newtonian fluids, noting that for creeping flow, the effects of viscous shearing are the dominant contribution to the total pressure drop along the contraction and that it is difficult to isolate purely extensional effects.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic extensional rheometry using a hyperbolic contraction geometry

et al. 2013

View full text Add to dashboard Cite

Microfluidic devices are ideally suited for the study of complex fluids undergoing large deformation rates in the absence of inertial complications. In particular, a microfluidic contraction geometry can be utilized to characterize the material response of complex fluids in an extensionally-dominated flow, but the mixed nature of the flow kinematics makes quantitative measurements of material functions such as the true extensional viscosity challenging. In this paper, we introduce the 'extensional viscometer-rheometer-on-a-chip' (EVROC), which is a hyperbolically-shaped contractionexpansion geometry fabricated using microfluidic technology for characterizing the importance of viscoelastic effects in an extensionally-dominated flow at large extension rates (λε a 1, where λ is the characteristic relaxation time, or for many industrial processesε a 1 s −1 ). We combine measurements of the flow kinematics, the mechanical pressure drop across the contraction and spatially-resolved flow-induced birefringence, to study a number of model rheological fluids as well as several representative liquid consumer products in

show abstract

“…While measurement of viscosity in visce metric flow is relatively common, measurement of viscosity in a purely extensional flow field presents an extremely challenging experimental problem for many materials. I t has been done relatively successfully for some materials in carefully controlled experiments (31,32). In the absence of data from such experiments, however, the modeler may have to resort to more approximate results gotten by simpler methods in order to have the inputs necessary to predict the filling of a die.…”

Section: Application To Rheornetric Datamentioning

confidence: 99%

Effect of extensional viscosity and wall quenching on modeling of mold fillings

Moller

Lee

Kibbel

et al. 1995

Polymer Engineering & Sci

View full text Add to dashboard Cite

A combined finite element and finite difference approach has been developed to include the capability to model fluid and thermal transport for the filling of a die cavity by a fluid that has differing sensitivities to extensional and shear deformation rates. This is referred to here as a dual viscosity fluid. For the case of mildly convergent or divergent quasi two‐dimensional flows, a viscosity model is described that has such a dual‐viscosity character and in which shear and extension rate sensitivities are nearly separated. Filling simulation results can be generated rapidly in a modest computational environment. The range of cavities and molding materials that may be modeled realistically is widened by the inclusion of a dual viscosity model. The effect of wall quenching (freezing) increased with decreasing filling rate, while the effect of dual viscosity increased with increasing filling rate.

show abstract

The extensional flow capillary as a new method for extensional viscosity measurement

Cited by 40 publications

References 4 publications

Microfluidic rheometry

Microfluidic rheometry

Microfluidic extensional rheometry using a hyperbolic contraction geometry

Effect of extensional viscosity and wall quenching on modeling of mold fillings

Contact Info

Product

Resources

About