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Research Papers: Flows in Complex Systems

Drag Reduction in Synthetic Seawater by Flexible and Rigid Polymer Addition Into a Rotating Cylindrical Double Gap Device

[+] Author and Article Information
Rafhael M. Andrade

Assistant Professor
Laboratory of Rheology—LabRheo,
Department of Mechanical Engineering,
Universidade Federal do Espírito Santo,
Vitória, ES 29075-910, Brazil
e-mail: rafhaelmilanezi@gmail.com

Anselmo S. Pereira

Laboratoire de Mécanique de Lille,
CNRS/UMR 8107,
Polytech'Lille,
Villeneuve d'Ascq 59655, France
e-mail: anselmo.pereira@polytech-lille.fr

Edson J. Soares

Associated Professor
Laboratory of Rheology—LabRheo,
Department of Mechanical Engineering,
Universidade Federal do Espírito Santo,
Vitória, ES 29075-910, Brazil
e-mail: edson.soares@ufes.br

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received December 18, 2014; final manuscript received July 30, 2015; published online September 2, 2015. Assoc. Editor: Mark F. Tachie.

J. Fluids Eng 138(2), 021101 (Sep 02, 2015) (10 pages) Paper No: FE-14-1766; doi: 10.1115/1.4031229 History: Received December 18, 2014; Revised July 30, 2015

Flexible and rigid long chain polymers in very dilute solutions can significantly reduce the drag in turbulent flows. The polymers successively stretch and coil by interacting with the turbulent structures, which changes the turbulent flow and further imposes a transient behavior on the drag reduction (DR) as well as a subsequent mechanical polymer degradation. This time-dependent phenomenon is strongly affected by a number of parameters, which are analyzed here, such as the Reynolds number, polymer concentration, polymer molecular weight, and salt concentration. This last parameter can dramatically modify the polymeric structure. The investigation of the salt concentration's impact on the DR is mostly motivated by some potential applications of this technique to ocean transport and saline fluid flows. In the present paper, a cylindrical double gap rheometer device is used to study the effects of salt concentration on DR over time. The reduction of drag is induced by three polymers: poly (ethylene oxide) (PEO), polyacrylamide (PAM), and xanthan gum (XG). These polymers are dissolved in deionized water both in the presence of salt and in its absence. The DR is displayed from the very start of the test to the time when the DR achieves its final level of efficiency, following the mechanical degradations. The presence of salt in PEO and XG solutions reduces the maximum DR, DRmax, as well as the time to achieve it. In contrast, the DR does not significantly change over the time for PAM solutions upon the addition of salt.

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References

Figures

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Fig. 1

The double gap geometry (Fig. 2 from Ref. [30])

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Fig. 2

Friction factor f as a function of Re for a range of concentrations of PEO in synthetic seawater and deionized water

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Fig. 3

Friction factor f as a function of Re for a range of concentrations of PAM in synthetic seawater and deionized water

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Fig. 4

Friction factor f as a function of Re for a range of concentrations of XG in synthetic seawater and deionized water

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Fig. 5

Friction factor f as a function of Re for different molecular weight of PEO in synthetic seawater and deionized water

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Fig. 6

Effects of synthetic sea salt concentration on Fanning friction factor f as a function Re for PEO

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Fig. 7

Effects of synthetic sea salt concentration on Fanning friction factor f as a function Re for PAM

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Fig. 8

Effects of synthetic sea salt concentration on Fanning friction factor f as a function Re for XG

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Fig. 9

DR(t) for a range of Re for PEO in synthetic seawater and deionized water

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Fig. 10

DR(t) for a range of Re for PAM in synthetic seawater and deionized water

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Fig. 11

DR(t) for a range of Re for XG in synthetic seawater and deionized water

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Fig. 12

DR(t) for a range of concentrations of PEO in synthetic seawater and deionized water

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Fig. 13

DR(t) for a range of concentrations of PAM in synthetic seawater and deionized water

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Fig. 14

DR(t) for a range of concentrations of XG in synthetic seawater and deionized water

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Fig. 15

DR(t) for different values of Mv of PEO in synthetic seawater and deionized water

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Fig. 16

DR(t) for PEO in different synthetic sea salt concentrations: SSW (3.5% by weight of synthetic sea salt) and SSW10% (10% by weight of synthetic sea salt)

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Fig. 17

DR(t) for PAM in different synthetic sea salt concentrations: SSW (3.5% by weight of synthetic sea salt) and SSW10% (10% by weight of synthetic sea salt)

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Fig. 18

DR(t) for XG in different synthetic sea salt concentrations: SSW 10 ppm (10 ppm by weight of synthetic sea salt), SSW (3.5% by weight of synthetic sea salt), and SSW10% (10% by weight)

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Fig. 19

DR(t) for XG solutions with synthetic seawater and deionized water previously sheared

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Fig. 20

DR as a function of temperature for XG solutions

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