Determination of material parameters of viscoelastic fluids by rotational non-viscometric flows

Mashelkar, R. A.; Kale, D. D.; Kelkar, J. V.; Ulbrecht, J.

doi:10.1016/0009-2509(72)80012-5

Cited by 13 publications

(1 citation statement)

References 12 publications

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“…Using this method, Manero and Mena (1978) acquired values of the second normal stress-difference; such findings lay in good agreement with the values obtained through other methods. In addition, some authors, such as Mashelkar et al (1972), Kelkar et al (1973), Acharya and Maaskant (1978), have used the torque as a function of rotation-speed, to assess the elastic-viscous parameters of some fluids. One of the most common difficulties in the effective use of torque measurements lies in the elimination of wall-effects, which may also affect the development of diverse flow patterns.…”

Section: Introductionmentioning

confidence: 99%

Shear-thinning and constant viscosity predictions for rotating sphere flows

Garduño

Tamaddon-Jahromi

Webster

2015

Mech Time-Depend Mater

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The steady motion of a rotating sphere is analysed through two contrasting viscoelastic models, a constant viscosity (FENE-CR) model and a shear-thinning (LPTT) model. Giesekus (Rheol. Acta 9:30-38, 1970) presented an intriguing rotating viscoelastic flow, which to date has not been completely explained. In order to investigate this flow, sets of parameters have been explored to analyse the significant differences introduced with the proposed models, while the momentum-continuity-stress equations are solved through a hybrid finite-element/finite volume numerical scheme. Solutions are discussed for first, sphere angular velocity increase (Ω), and second, through material velocity-scale increase (α). Numerical predictions for different solvent-ratios (β) show significant differences as the sphere angular velocity increases. It is demonstrated that an emerging equatorial anticlockwise vortex emerges in a specific range of Ω. As such, this solution matches closely with the Giesekus experimental findings. Additionally, inside the emerging inertial vortex, a contrasting positive second normal stress-difference (N 2 (γ ) = τ rr − τ θθ ) region is found compared against the negative N 2 -enveloping layer.

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Section: Introductionmentioning

confidence: 99%

Shear-thinning and constant viscosity predictions for rotating sphere flows

Garduño

Tamaddon-Jahromi

Webster

2015

Mech Time-Depend Mater

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Drag reduction in dilute polymer solutions

Kelkar

Mashelkar

1972

J of Applied Polymer Sci

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synopsisThe problem of drag reduction in a helically coiled tube is examined experimentally. The general problems involved in the correlation of drag reduction data are analyzed critically, and some important recommendations are made based on the findings of this work. A phenomenological approach is suggested for correlating the drag reduction data. An examination of the straight-tube data from the literature and the coiledtube data obtained in this work shows that for a variety of aqueous polymer solutions the data could be uniquely correlated by the following equation:where fl = reduced friction factor and De' = modified Deborah number.The problem of drag reduction under turbulent flow conditions by the addition of small quantities of high molecular weight polymers has been extensively studied in the literature. The majority of the work has been done in straight tubes, and there is little information in the literature on drag reduction under conditions when the fluids are flowing in flow situations other than straight tubes. Many tentative explanations have been offered to explain the phenomenon of drag reduction but none of them is entirely convincing. Many phenomenological and molecular approaches have been used to correlate the drag reduction data but I I critical analysis of these approaches has not been attempted before.In view of the factors mentioned above, we have undertaken an experimental study of drag reduction in one such interesting situation, namely, in helically coiled tubes. We have critically analyzed the general problem of correlation of drag reduction data and we have proposed a phenomenological approach for correlating such data. We have then shown that such a correlation enables us to correlate the data for different dilute aqueous polymer solutions flowing in a variety of flow situations.

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A rotating sphere viscometer

Kelkar

Mashelkar

Ulbrecht

1973

J of Applied Polymer Sci

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synopsisThe use of a rotating sphere viscometer for the measurement of parameters in the flow curves of inelastic as well as viscoelastic liquids is examined. An experimental investigation of the primary flow around a sphere rotating in Newtonian and viscoelastic liquids is carried out by using a new "three-dimensional particle technique." Currently available theoretical analyses of rotation of a sphere in viscoelastic liquids are shown to be inadequate to describe the experimental primary velocity distribution data. Theoretical results for the primary distribution derived on the basis of a creeping flow of a power law liquid are found to describe the experimental data well. This distribution is then used to derive torque-angular velocity relationships, which are then confirmed experimentally for both inelastic and viscoelastic liquids. The results of this work justify the use of a rotating sphere viscometer as a useful tool for the measurement of parameters of flow curves of inelastic and visccelastic liquids.

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Determination of material parameters of viscoelastic fluids by rotational non-viscometric flows

Cited by 13 publications

References 12 publications

Shear-thinning and constant viscosity predictions for rotating sphere flows

Shear-thinning and constant viscosity predictions for rotating sphere flows

Drag reduction in dilute polymer solutions

A rotating sphere viscometer

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