Polymer Chain Scission In Extensional And Turbulent Flows And Implications For Friction Drag Technologies
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Polymer Chain Scission In Extensional And Turbulent Flows And Implications For Friction Drag Technologies
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Author : Siva A. Vanapalli
language : en
Publisher:
Release Date : 2006
Polymer Chain Scission In Extensional And Turbulent Flows And Implications For Friction Drag Technologies written by Siva A. Vanapalli and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
Handbook Of Applied Polymer Processing Technology
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Author : Nicholas P. Cheremisinoff
language : en
Publisher: CRC Press
Release Date : 2020-10-07
Handbook Of Applied Polymer Processing Technology written by Nicholas P. Cheremisinoff and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-10-07 with Technology & Engineering categories.
"Offers detailed coverage of applied polymer processing--presenting a wide range of technologies and furnishing state-of-the-art data on polymer components, properties, and processibility. Reviews fundamental rheological concepts. Contains over 1600 bibliographic citations, some 450 equations, and over 400 tables, drawings, and photographs."
Flexible Polymer Chains In Elongational Flow
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Author : Tuan Q. Nguyen
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Flexible Polymer Chains In Elongational Flow written by Tuan Q. Nguyen and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Technology & Engineering categories.
The behavior of polymer solutions in simple shear flows has been the subject of considerable research in the past. On the other hand, reports on polymers in elongational flow have appeared comparatively recently in the literature. Elongational flow with an inherent low vorticity is known to be more effective in extending polymer chains than simple shear flow and thus is more interesting from the point of view of basic (molecular chain dynamics at high deformation) and applied polymer science (rheology, fiber extrusion, drag reduction, flow through porous media). Undoubtly, one landmark in the field of polymer dynamics in elongational flow was the notion of critical strain-rate for chain extension, initially put forward by A. Peterlin (1966) and later refined into the "coil-stretching" transition by P. G. de Gennes and H. Hinch (1974). In the two decades which followed, significant progress in the understanding of chain conformation in "strong" flow has been accomplished through a combination of advances in instrumentation, computation techniques and theoretical studies. As a result of the multidisciplinary nature of the field, information on polymer chains in "strong" flow is accessible only from reviews and research papers scattered in disparate scientific journals. An important objective of this book is to remedy that situation by providing the reader with up-to-date knowledge in a single volume. The editors therefore invited leading specialists to provide both fundamental and applied information on the multiple facets of chain deformation in elongational flow.
Polymers And Plastrons
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Author : Anoop Rajappan
language : en
Publisher:
Release Date : 2020
Polymers And Plastrons written by Anoop Rajappan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Frictional energy dissipation in wall-bounded turbulence is ubiquitous in modern engineering systems, ranging from the flow of liquids through pipelines, to the drag-inducing boundary layer around ships and submarines. The effective mitigation of this frictional drag is therefore of great practical interest, and offers substantial economic and environmental benefits. This thesis focuses on two complementary techniques for turbulent drag reduction--the active injection of polymers into the flow, and the passive aerophilic texturing of the wall--and aims to address practical challenges that prevent their widespread adoption in real-life systems, with an emphasis on marine applications. The prohibitive cost of synthetic polymers remains a key impediment to their large-scale deployment in commercial marine operations. This thesis hence focuses on affordable and readily accessible sources of high molecular weight biopolymers: specifically, the water-soluble fiber, or mucilage, extracted from seeds such as flax, chia and psyllium. By means of frictional drag measurements inside a bespoke Taylor-Couette apparatus, seed mucilage is shown herein to display drag reduction efficacy and flow longevity comparable to common synthetic polymers, while offering significant advantages in terms of raw material cost and biodegradability. Preliminary investigations confirm that oil-soluble natural polymers, such as rubber latex, can analogously be employed as eco-friendly drag reducers for the transport of hydrocarbon feedstocks. Superhydrophobic texturing of submerged flow boundaries has emerged recently as another viable method of drag reduction in aqueous flows. Despite sustained research interest in both polymers and superhydrophobic walls as standalone methods for drag mitigation, attempts to employ them jointly has remained unsuccessful. In this thesis, cooperative drag reduction effects are explored for two common drag-reducing polymers, paired with regularly patterned as well as randomly textured superhydrophobic walls. Dissolved flexible macromolecules are shown to act in concert with the slip-inducing air layer, or plastron, trapped atop the superhydrophobic texture, yielding enhanced reductions in turbulent drag greater than that achievable from either method employed independently. An additive law in Prandtl-von Kármán coordinates is derived that accurately predicts this combined effect at dilute polymer concentrations, and the adverse influence of the surface activity of polymers on wall slip is also elucidated.
Chain Scission In Turbulent Flow Of Dilute Polymer Solutions
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Author : Brian G. Price
language : en
Publisher:
Release Date : 2002
Chain Scission In Turbulent Flow Of Dilute Polymer Solutions written by Brian G. Price and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Polymer solutions categories.
Analytical And Experimental Study Of Turbulent Flow Drag Reduction And Degradation With Polymer Additives
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Author : Xin Zhang
language : en
Publisher:
Release Date : 2020
Analytical And Experimental Study Of Turbulent Flow Drag Reduction And Degradation With Polymer Additives written by Xin Zhang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Flow friction reduction by polymers is widely applied in the oil and gas industry for flow enhancement or to save pumping energy. The huge benefit of this technology has attracted many researchers to investigate the phenomenon for 70 years, but its mechanism is still not clear. The objective of this thesis is to investigate flow drag reduction with polymer additives, develop predictive models for flow drag reduction and its degradation, and provide new insights into the drag reduction and degradation mechanism. The thesis starts with a semi-analytical solution for the drag reduction with polymer additives in a turbulent pipe flow. Based on the FENE-P model, the solution assumes complete laminarization and predicts the upper limitation of drag reduction in pipe flows. A new predictive model for this upper limit is developed considering viscosity ratios and the Weissenberg number - a dimensionless number related to the relaxation time of polymers. Next, a flow loop is designed and built for the experimental study of pipe flow drag reduction by polymers. Using a linear flexible polymer - polyethylene oxide (PEO) - in water, a series of turbulent flow experiments are conducted. Based on Zimm's theory and the experimental data, a correlation is developed for the drag reduction prediction from the Weissenberg number and polymer concentration in the flow. This correlation is thoroughly validated with data from the experiments and previous studies as well. To investigate the degradation of drag reduction with polymer additives, a rotational turbulent flow is first studied with a double-gap rheometer. Based on Brostow's assumption, i.e., the degradation rate of drag reduction is the same as that of the molecular weight decrease, a correlation of the degradation of drag reduction is established, along with the proposal of a new theory that the degradation is a first-order chemical reaction based on the polymer chain scission. Then, the accuracy of the Brostow's assumption is examined, and extensive experimental data indicate that it is not correct in many cases. The degradation of drag reduction with polymer additives is further analyzed from a molecular perspective. It is found that the issue with Brostow's theory is mainly because it does not consider the existence of polymer aggregates in the flow. Experimental results show that the molecular weight of the degraded polymer in the dilute solution becomes lower and the molecular weight distribution becomes narrower. An improved mechanism of drag reduction degradation considering polymer aggregate is proposed - the turbulent flow causes the chain scission of the aggregate and the degraded aggregate loses its drag-reducing ability. Finally, the mechanism of drag reduction and degradation is examined from the chemical thermodynamics and kinetics. The drag reduction phenomenon by linear flexible polymers is explained as a non-spontaneous irreversible flow-induced conformational-phase-change process that incorporates both free polymers and aggregates. The entire non-equilibrium process is due to the chain scission of polymers. This theory is shown to agree with drag reduction experimental results from a macroscopic view and polymer behaviours from microscopic views. The experimental data, predictive models, and theories developed in this thesis provide useful new insights into the design of flow drag reduction techniques and further research on this important physical phenomenon.
Various Aspects Of Polymer Induced Drag Reduction In Turbulent Flow
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Author :
language : en
Publisher:
Release Date : 2011
Various Aspects Of Polymer Induced Drag Reduction In Turbulent Flow written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Applied Mechanics Reviews
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Author :
language : en
Publisher:
Release Date : 1995
Applied Mechanics Reviews written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Mechanics, Applied categories.
Dissertation Abstracts International
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Author :
language : en
Publisher:
Release Date : 2006
Dissertation Abstracts International written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Dissertations, Academic categories.
Effect Of Dilute Polymer Solutions On The Turbulence Characteristics And The Frictional Drag Of External Flows
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Author : T. Kowalski
language : en
Publisher:
Release Date : 1969
Effect Of Dilute Polymer Solutions On The Turbulence Characteristics And The Frictional Drag Of External Flows written by T. Kowalski and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1969 with categories.