Drag Reduction by Polymer Additives

Diamond, P. H.; Harvey, Jack; Katz, J. I.; Nelson, Donald S.; Steinhardt, Paul J.

doi:10.21236/ada258867

Cited by 7 publications

(6 citation statements)

References 17 publications

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“…This is explained by the velocity increases that occurs in these fluids while keeping Reynolds number constant and not due to the friction factor f, as it was explained above in the analysis of the polymer concentration effect. These results are in agreement with those found experimentally by Virk (apud Diamond [5] and Wójs [6]), even in their case the latter study has modeled the viscoelastic fluid by the power law. No drag reduction effects were also verified by Zheng et al [7] and Oliveira [8] for a rectangular cross section in laminar regime.…”

Section: Viscous Effectsupporting

confidence: 92%

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Influence Study of the Viscoelastic Fluids Features in Drag Reduction in Laminar Regime Flow in Pipeline

Vilalta

Silva

Blanco³

2016

MATEC Web Conf.

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Abstract. The drag reduction by polymer addition is wide interest in several areas. It has been shown that the polymer addition cushions the dissipative effects in turbulent flows. The main objective of this work is to establish a methodology for the numerical simulation of viscoelastic fluid through internal subroutines implemented in the Fluent code, via UDF. The validation of this methodology is made for the laminar flow regime case in pipeline. To describe the viscoelastic effect, it was used the Finitely Extensible Nonlinear Elastic model closing with Peterlin model. To taking in account the viscous effects 50 Re 2000 values were used. In addition, for the polymer concentration analysis it was used values which depend on the polymers molecular weight and the solution concentration that ranged from 0 Cw 20. The molecular elasticity and extensibility were maintained at constant values. The results showed that the addition of polymers regardless of their molecular weight in laminar flow regime causes no change in power dissipation. This result, which is consistent with the literature, is a significant advance in defining a credible and appropriate methodology to viscoelastic fluid flow study by UDF implementation of constituent models that characterize these fluids.

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Section: Viscous Effectsupporting

confidence: 92%

“…In addition, there is a consensus in the researches conducted to date that it is possible to check that the effect of drag reduction, by polymers injection in pipes, is highly effective in turbulent regime, but does not seem to have an effect on laminar flow regime [3], [5], [6].…”

Section: Introductionmentioning

confidence: 99%

Influence Study of the Viscoelastic Fluids Features in Drag Reduction in Laminar Regime Flow in Pipeline

Vilalta

Silva

Blanco³

2016

MATEC Web Conf.

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“…It is noteworthy that the videos Schneider et al provide shows a vWF molecule extending and contracting in the bulk flow unattached to a surface. The author states that the protein “immediately” relaxes back to its compact state when the shear force is reduced, though this relaxation time [Zimm time, from Diamond et al ] must have a finite value. Schneider et al reported that a conformational transition takes place in a reversible manner and on very short time scales—on the order of milliseconds.…”

Section: What Level Of Shear Stress and For How Long Of An Exposure Wmentioning

confidence: 99%

Acquired Von Willebrand Syndrome and Blood Pump Design

et al. 2018

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The existence of acquired von Willebrand syndrome (AVWS) in patients with continuous flow left ventricular assist devices (LVADs) is well documented and has been verified by numerous investigators. AVWS has not been observed to occur in pulsatile devices such as the SynCardia total artificial heart (TAH), the HeartMate XVE, and the Thoratec pulsatile ventricular assist device (PVAD) used as a single pump. AVWS can also occur in patients with aortic stenosis, ventricular septal defect, mitral stenosis, and patent ductus arteriosus. It has been experimentally verified that supraphysiologic shear stress that occurs under these conditions can cleave the von Willebrand molecule, but the critical magnitude of stress and duration is unclear. Limited experimental results demonstrate that shear stresses as low as 5 Pa (50 dyne/cm2) can cause cleavage. Stresses in current centrifugal pumps can be as high as two orders of magnitude greater than this value. Pulsatile LVADs have stresses almost two orders of magnitude less than continuous flow LVADs. In order to improve continuous flow LVADs, the challenge for designers is to first determine the magnitude and duration of stress that is causing AVWS and then, if possible, design a pump below these stresses.

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“…Diamond et al 1992 "Drag Reduction by Polymer Additives," JSR-89-720. >■ Extending , proposed a coupled tensor-field description of the local elastic-elongation response of a dilute polymer solution to…”

Section: Previous Jason Work -Iimentioning

confidence: 99%

“…The Diamond et al (1992) JSR-89-720 report provided an important summary of ideas at the time, as well as a significant impetus and guidance for this year's study. It identifies the mechanisms and dynamics that couple polymer-elastization fields and turbulence.…”

Section: Jason 2000 Drag Reductionmentioning

confidence: 99%