Scission-induced bounds on maximum polymer drag reduction in turbulent flow

Vanapalli, Siva A.; Islam, Mohammad Tariqul; Solomon, Michael J.

doi:10.1063/1.2042489

Cited by 67 publications

(65 citation statements)

References 44 publications

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“…In pipe flows, Horn and Merrill (1984) have shown that the polymer chains break near the midpoint, effectively reducing the polymer molecular weight by 50%. Vanapalli et al (2005) and developed relationships relating the near-wall shear to the degradation of PEO with various molecular weights, and their results indicate that chain-scission occurs in PEO solutions at shear rates much lower than those of previous TBL studies and the present experiments.…”

Section: Introductionmentioning

confidence: 82%

High Reynolds Number Micro-Bubble and Polymer Drag Reduction Experiments

Ceccio¹,

Dowling²,

Perlin³

et al. 2008

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Background: This effort was a continuation of the joint ONR and DARPA programs of the PI and Co-PI's initiated as part of the DARPA Friction Drag Reduction Program (ATO/TTO). The purpose of the investigation was to examine the physics and engineering of friction drag reduction methods for turbulent boundary layers (TBL) found in hydrodynamic flows. Three methods of friction drag reduction (FDR) were examined:" Polymer Drag Reduction-solutions containing extensible, long-chain molecules ' are injected into a TBL. The polymer molecules interact with the underlying turbulent flow and lead to a reduction of the correlated velocity fluctuations and, hence, a reduction of the turbulent transport of momentum across the TBL. This leads to local drag reduction of up to -70% for a TBL flow over smooth surfaces compared to a flow without polymer injection.* Micro-bubble Drag Reduction-air is injected into the TBL with the aim of producing a large volume of small bubbles in the near-wall region of the TBL. The presence of the bubbles reduces the bulk density of the fluid near the wall and possibly alters the turbulent velocity fluctuations. These effects can combine to locally reduce the friction drag over 80%." Air Layer Drag Reduction-air is injected into the TBL with the aim of creating a stable gas layer of very high void fraction (> 80% void fraction), separating the liquid flow from the solid surface. This results in friction drag reductions of over 80% compared to the friction drag of an unmodified TBL. DISTRIBUTION STATEMENT A 20080131 272 Approved for Public ReleaseDistribution UnlimitedThese FDR methods have been studied for some time on the laboratory scale, yielding a great deal of information on their engineering potential and underlying methods. However, the flow physics responsible for FDR does not easily scale from the laboratory to full-scale hydrodynamic applications. Hence, our effort focused on conducting a series of experiments at both large size scales and high Reynolds numbers in order to further explore the flow physics and practicality of these FDR methods.Our experiments were performed on a canonical TBL flow formed on a flat plate, zeropressure gradient boundary layer. The maximum length of the test model was -10 m, and the maximum velocity of the flow was -20 m/s, making the Reynolds number based on maximum length -200 million. Our experiments were conducted in the William B.Morgan Large Cavitation Channel (LCC), owed and operated by the Naval Surface Warfare Center-Carderock Division of the U. S. Navy.During this portion of our research program, three rounds of testing in the LCC were conducted:* Phase III (Polymer FDR) * Phase IV (MBDR/ALDR) * Phase V (Polymer FDR).Two additional rounds of testing were conducted under the first portion of ONR and DARPA support: Phase I was a baseline test of the model, and Phase II was on MBDR. Also, a portion of Phase V was devoted to examining the influence of roughness on Polymer FDR and ALDR. This portion of the effort was supported under DARPA contract "...

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Section: Introductionmentioning

confidence: 82%

High Reynolds Number Micro-Bubble and Polymer Drag Reduction Experiments

Ceccio¹,

Dowling²,

Perlin³

et al. 2008

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“…Until now, some researches [60,[64][65][66][67][68][69] have indicated that polymer molecular weight, molecular weight distribution, temperature, solvent solubility, polymer concentration, turbulent intensity, preparation and storage methods, entrance or end effects, and flow geometry may influence polymer degradation in turbulent flows. Nevertheless, it is noteworthy that due to various experimental conditions some conflicting results still exist when explaining degradation with the above factors.…”

Section: Effects Of Polymer Degradationmentioning

confidence: 99%

“…After realizing that degradation results in reduction of numbers of monomers in a molecule, Vanapalli et al [65] derived a relationship between the critical shear ratėand the molecular weight for degradation of PEO solutions followinġ∼ − , where the exponent was determined to be 2.2 for the turbulent flow with entrance effect. Following this result, Winkel et al [49] obtained a detailed equation for the degradation of PEO in the turbulent pipe flow aṡ = 3.23 × 10 18 × −2.20 .…”

Section: Effects Of Polymer Degradationmentioning

confidence: 99%

A Short Review on Drag-Reduced Turbulent Flow of Inhomogeneous Polymer Solutions

Kawaguchi

2013

Advances in Mechanical Engineering

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Turbulent drag reduction by additives is an effective approach to save energy in wall turbulence. Improvement of this approach requires a better understanding of the interactions between turbulence and additives including the complex changes in turbulence under various conditions of additives. In this paper we review some recent progress in the investigations of drag reduction in wall turbulence with inhomogeneous polymer solutions via slot-injection and wall-blowing methods. The turbulent statistics characteristics and coherent structures modified by the inhomogeneous polymer additives and the polymer diffusion characteristics in the turbulent boundary layer (TBL) flow and channel flow are discussed in terms of previous experimental and numerical studies. This review also presents a discussion of current limitations and future directions in these areas. Readers may find it helpful in understanding the phenomenon of turbulent drag reduction by inhomogeneous polymer additives and in developing practical applications.

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“…Several studies have underlined the advantages of such microfluidic devices [20][21][22][23][24]. In EVROC system, an extensional rate ε · is imposed through a controlled flow rate Q, the resulting extensional pressure drop ΔP ext is measured and the extensional viscosity η ext can be inferred: (11) where υ is a characteristic volume [25,26]. Data for extensional and shear viscosities are often compared using the Trouton number Tr: Picture and schematic representation of the API device used to induce mechanical degradation.…”

Section: Rheological Characterizationmentioning

confidence: 99%

“…As for turbulent flows, to our knowledge, only Vanapalli et al [11] established a relationship between a critical scission strain rate ε · c and molecular weight M, for polyethylene oxide dilute solutions: (4) with U c : critical mean velocity in the pipe of diameter D.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Degradation Onset of Polyethylene Oxide Used as a Hydrosoluble Model Polymer for Enhanced Oil Recovery

Dupas

Hénaut

Argillier

et al. 2012

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Résumé -Seuil de dégradation mécanique de solutions de polymères utilisés en récupération assistée des hydrocarbures -Les polymères hydrosolubles comme les polyacrylamides peuvent être utilisés en récupération assistée des hydrocarbures (Enhanced Oil Recovery (EOR)) par injection de polymère. Cette technique vise à augmenter la production de brut en le poussant du réservoir vers un puits producteur à l'aide d'une solution de polymère suffisamment visqueuse. Les polymères utilisés à cet effet ont des masses moléculaires supérieures à 10 6 g/mol, ce qui les rend sensibles à la dégradation. En raison des débits élevés utilisés lors de leur injection, mais aussi en raison des taux d'élongation élevés rencontrés dans le réservoir, les polymères peuvent se rompre et perdre leurs propriétés viscosifiantes. Dans la littérature, il a été clairement montré, pour des solutions diluées en régime laminaire, que la dégradation des macromolécules n'était initiée qu'au-delà d'un taux d'élongation critique noté ε · c , et que ce taux d'élongation était une fonction puissance de la masse moléculaire du polymère : ε · c ≈ M w -k . La présente étude expérimentale de la dégradation mécanique a été menée sur des solutions d'oxydes de polyéthylène pour comprendre la dégradation mécanique non seulement en écoulement laminaire ou turbulent, mais aussi en régime dilué et semi-dilué, ainsi qu'en bon ou mauvais solvant. Il a été mis en évidence que la dégradation mécanique affecte principalement les longues chaînes, qu'elle est favorisée à concentrations élevées et en mauvais solvant. Les résultats montrent également que la décroissance de la viscosité élongationnelle à faibles taux de déformation, due à la dégradation, est semblable à celle de la viscosité de cisaillement ; elle est en revanche beaucoup plus marquée à forts taux d'élongation. Abstract

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Scission-induced bounds on maximum polymer drag reduction in turbulent flow

Cited by 67 publications

References 44 publications

High Reynolds Number Micro-Bubble and Polymer Drag Reduction Experiments

High Reynolds Number Micro-Bubble and Polymer Drag Reduction Experiments

A Short Review on Drag-Reduced Turbulent Flow of Inhomogeneous Polymer Solutions

Mechanical Degradation Onset of Polyethylene Oxide Used as a Hydrosoluble Model Polymer for Enhanced Oil Recovery

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