Download or read book Turbulent Drag Reduction by Surfactant Additives written by Feng-Chen Li and published by John Wiley & Sons. This book was released on 2012-01-10 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent drag reduction by additives has long been a hot research topic. This phenomenon is inherently associated with multifold expertise. Solutions of drag-reducing additives are usually viscoelastic fluids having complicated rheological properties. Exploring the characteristics of drag-reduced turbulent flows calls for uniquely designed experimental and numerical simulation techniques and elaborate theoretical considerations. Pertinently understanding the turbulent drag reduction mechanism necessities mastering the fundamentals of turbulence and establishing a proper relationship between turbulence and the rheological properties induced by additives. Promoting the applications of the drag reduction phenomenon requires the knowledge from different fields such as chemical engineering, mechanical engineering, municipal engineering, and so on. This book gives a thorough elucidation of the turbulence characteristics and rheological behaviors, theories, special techniques and application issues for drag-reducing flows by surfactant additives based on the state-of-the-art of scientific research results through the latest experimental studies, numerical simulations and theoretical analyses. Covers turbulent drag reduction, heat transfer reduction, complex rheology and the real-world applications of drag reduction Introduces advanced testing techniques, such as PIV, LDA, and their applications in current experiments, illustrated with multiple diagrams and equations Real-world examples of the topic’s increasingly important industrial applications enable readers to implement cost- and energy-saving measures Explains the tools before presenting the research results, to give readers coverage of the subject from both theoretical and experimental viewpoints Consolidates interdisciplinary information on turbulent drag reduction by additives Turbulent Drag Reduction by Surfactant Additives is geared for researchers, graduate students, and engineers in the fields of Fluid Mechanics, Mechanical Engineering, Turbulence, Chemical Engineering, Municipal Engineering. Researchers and practitioners involved in the fields of Flow Control, Chemistry, Computational Fluid Dynamics, Experimental Fluid Dynamics, and Rheology will also find this book to be a much-needed reference on the topic.

Download or read book Turbulent Drag Reduction by Additives written by Dilafruz Kulmatova and published by . This book was released on 2013 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: The addition of a minute amount of polymer or surfactant additive to a turbulent fluid flow can result in a large reduction in the frictional drag in pipes and channels. Over the past decades, numerous studies have been carried out on drag reducing additives (DRA). DRA have been successfully applied for potential benefits in various industrial processes, including oil well operations, heating and cooling water circuits, marine and biomedical systems. The use of additives to enhance flow in petroleum pipelines has received the greatest attention due to its great commercial success in reducting cost and energy consumption. Although this effect has been known for almost half a century, the detailed mechanism of drag reduction have still not been clearly identified and is still a subject of ongoing controversy. The aim of this thesis is to develop an understanding of the role of drag reducing agents and to explain the nature of drag reduction mechanism. This could have an impact on the design of efficient pumping systems, the design of drag-reducing agent that are more stable over time, and the modeling of mixing processes that could be an important consideration in designing practical systems.

Download or read book Drag Reduction of Turbulent Flows by Additives written by A. Gyr and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 243 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drag Reduction of Turbulent Flows by Additives is the first treatment of the subject in book form. The treatment is extremely broad, ranging from physicochemical to hydromechanical aspects. The book shows how fibres, polymer molecules or surfactants at very dilute concentrations can reduce the drag of turbulent flow, leading to energy savings. The dilute solutions are considered in terms of the physical chemistry and rheology, and the properties of turbulent flows are presented in sufficient detail to explain the various interaction mechanisms. Audience: Those active in fundamental research on turbulence and those seeking to apply the effects described. Fluid mechanical engineers, rheologists, those interested in energy saving methods, or in any other application in which the flow rate in turbulent flow should be increased.

Download or read book Direct Numerical Simulation of Turbulent Drag Reduction by Rigid Fiber Additives written by Amin Moosaie and published by . This book was released on 2011 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure of Turbulence and Drag Reduction written by Albert Gyr and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 617 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1976 a similar titled IUTAM Symposium (Structure of Turbulence and Drag Reduction) was held in Washington . However, the progress made during the last thirteen years as weil as the much promising current research desired a second one this year. In Washington drag reduction by additives and by direct manipulation of the walls (compliant walls and heated surfaces) were discussed. In the meantime it became evident that drag reduction also occurs when turbulence is influenced by geometrical means, e.g. by influencing the pressure distribution by the shape of the body (airfoils) or by the introduction of streamwise perturbances on a body (riblets). In the recent years turbulence research has seen increasing attention being focused on the investigation of coherent structures, mainly in Newtonian fluids. We all know that these structures are a significant feature of turbulent flows, playing an important role in the energy balance in such flows. However their place in turbulence theories as weil as the factors influencing their development are still poorly understood. Consequently, the investigation of phenomena in which the properties of coherent structures are alte red provides a promising means of improving our understanding of turbulent flows in general.

Download or read book Turbulent Flow Enhancement by Polyelectrolyte Additives written by David Leonard Wagger and published by . This book was released on 1992 with total page 1772 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Effect of Elasticity on Drag Reduction Due to Polymer Additives Using a Hybrid D N S and Langevin Dynamics Approach written by Arnout Boelens and published by . This book was released on 2012 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work the effect of elasticity on turbulent drag reduction due to polymers is investigated using a hybrid Direct Numerical Simulation (D.N.S) and Langevin dynamics approach. Simulations are run at a friction Reynolds number of Re_ & tau = 560 for 960.000 dumbbells with Deborah numbers of De = 0, De = 1, and De = 10. The conclusions are that it is possible to simulate a drag reduced flow using hybrid D.N.S. with Langevin dynamics, that polymers, like other occurrences of drag reduction, reduce drag through streak stabilization, and that the essential property of polymers and fibers in having a drag reducing effect is their ability to exert a torqueon the solvent when they orientate in the boundary layer of the turbulent flow.

Download or read book Drag Reduction by Polymer Additives in a Turbulent Pipe Flow written by Jacob Marinus Jan den Toonder and published by . This book was released on 1995 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Recent Developments in Turbulence Management written by K.-S. Choi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: The European Drag Reduction Meeting has been held on 15th and 16th November 1990 in London. This was the fifth of the annual European meetings on drag reduction in engineering flows. The main objective of this meeting was to discuss up-to-date results of drag reduction research carried out in Europe. The organiser has adopted the philosophy of discussing the yesterday's results rather than the last year's results. No written material has therefore been requested for the meeting. It was only after the meeting the submission of papers was requested to the participants, from which 16 papers were selected for this proceedings volume. The meeting has attracted a record number of participants with a total of 52 researchers from seven European countries, U. K. , France, Germany, the Netherlands, Italy, Switzerland and U. S. S. R. as well as from Japan, Canada and Australia. The subjects covered in this proceedings volume include riblets, LEBUs (Large Eddy Break-Up device), surface roughness, compliant surfaces and polymer additives. Riblets seem to be one of the most extensively studied devices in the past years. Reflecting this situation in the European community, there are six papers on riblets covering their practical applications to aircraft and to a model ship, near-wall coherent structure of the boundary layer and effects of flow three-dimensionality. Possibility of heat-transfer enhancement with riblets and potential use in the laminar flow are also investigated. An analytical model is developed for the boundary-layer with a LEBU device.

Download or read book Turbulence and Drag Reduction with Polymer Additives written by Alan White and published by . This book was released on 1972 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rheology of Drag Reducing Fluids written by Aroon Shenoy and published by Springer Nature. This book was released on 2020-03-25 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: ​This book explains theoretical derivations and presents expressions for fluid and convective turbulent flow of mildly elastic fluids in various internal and external flow situations involving different types of geometries, such as the smooth/rough circular pipes, annular ducts, curved tubes, vertical flat plates, and channels. Understanding the methodology of the analyses facilitates appreciation for the rationale used for deriving expressions of parameters relevant to the turbulent flow of mildly elastic fluids. This knowledge serves as a driving force for developing new ideas, investigating new situations, and extending theoretical analyses to other unexplored areas of the rheology of mildly elastic drag reducing fluids.The book suits a range of functions--it can be used to teach elective upper-level undergraduate or graduate courses for chemical engineers, material scientists, mechanical engineers, and polymer scientists; guide researchers unexposed to this alluring and interesting area of drag reduction; and serve as a reference to all who want to explore and expand the areas dealt with in this book.

Download or read book Viscous Drag Reduction written by C. Sinclair Wells and published by Springer. This book was released on 2013-12-20 with total page 497 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Drag Reduction written by Pouria Baghaei and published by LAP Lambert Academic Publishing. This book was released on 2012 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drag reduction is a remarkable ability to reduce the frictional resistance in the turbulent flow by adding a low concentration of certain additives, drag reducing additive agents (DRA). High costs of fluid transportation (such as pumping the liquids into the pipelines) in production processes has made drag reduction subject of lots of research in the past decades. Several studies have been carried out on reducing the friction factor in flow system using different drag reducing agents. However, there are a few investigations carried out on the effects of combining two or more DRAs. The purpose of this study is to investigate the effects of different additives on drag reduction using various methods. Effects of Polymer, Air bubbles, Aerofroth, and their combination have been investigated through the experimental study.

Download or read book Turbulent Drag Reduction by Polymers Surfactants and Their Mixtures in Pipeline Flow written by Ali Asghar Mohsenipour and published by . This book was released on 2011 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lthough extensive research work has been carried out on the drag reduction behavior of polymers and surfactants alone, little progress has been made on the synergistic effects of combined polymers and surfactants. A number of studies have demonstrated that certain types of polymers and surfactants interact with each other to form surfactant-polymer complexes. The formation of such complexes can cause changes in the solution properties and may result in better drag reduction characteristics as compared with pure additives. A series of drag-reducing surfactants and polymers were screened for the synergistic studies. The following two widely used polymeric drag reducing agents (DRA) were chosen: a copolymer of acrylamide and sodium acrylate (referred to as PAM) and polyethylene oxide (PEO). Among the different types of surfactants screened, a cationic surfactant octadecyltrimethylammonium chloride (OTAC) and an anionic surfactant Sodium dodecyl sulfate (SDS) were selected for the synergistic study. In the case of the cationic surfactant OTAC, sodium salicylate (NaSal) was used as a counterion. No counterion was used with anionic surfactant SDS. The physical properties such as viscosity, surface tension and electrical conductivity were measured in order to detect any interaction between the polymer and the surfactant. The drag reduction (DR) ability of both pure and mixed additives was investigated in a pipeline flow loop. The effects of different parameters such as additive concentration, type of water (deionized (DI) or tap), temperature, tube diameter, and mechanical degradation were investigated. The addition of OTAC to PAM solution has a significant effect on the properties of the system. The critical micelle concentration (CMC) of the mixed surfactant-polymer system is found to be different from that of the surfactant alone. The anionic PAM chains collapse upon the addition of cationic OTAC and a substantial decrease in the viscosity occurs. The pipeline flow behaviour of PAM/OTAC mixtures is found to be consistent with the bench scale results. The drag reduction ability of PAM is reduced upon the addition of OTAC. At low concentrations of PAM, the effect of OTAC on the drag reduction behavior is more pronounced. The drag reduction behavior of polymer solutions is strongly influenced by the nature of water (de-ionized or tap). The addition of OTAC to PEO solution exhibited a week interaction based on the viscosity and surface tension measurements. However, the pipeline results showed a considerable synergistic effect, that is, the mixed system gave a significantly higher drag reduction (lower friction factors) as compared with the pure additives (pure polymer or pure surfactant). The synergistic effect in the mixed system was stronger at low polymer concentrations and high surfactant concentrations. Also the resistance against mechanical degradation of the additive was improved upon the addition of OTAC to PEO. The mixed PEO/SDS system exhibited a strong interaction between the polymers (PEO) and the surfactant (SDS), Using electrical conductivity and surface tension measurements, the critical aggregation concentration (CAC) and the polymer saturation point (PSP) were determined. As the PEO concentration is increased, the CAC decreases and the PSP increase. The addition of SDS to the PEO solution exhibits a remarkable increase in the relative viscosity compared to the pure PEO solution. This increase is attributed to the changes in the hydrodynamic radius of the polymer coil. The pipeline flow exhibited a considerable increase in DR for the mixed system as compared to the pure PEO solution. The addition of surfactant always improves the extent of DR up to the PSP. Also the mixed PEO/ SDS system shows better resistance against shear degradation of the additive.

Download or read book A Study of Drag Reduction with Polymer Additive in Both Turbulent and Laminar Flow written by Humberto Jose Aquino and published by . This book was released on 1973 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Turbulence Suppression and Viscous Drag Reduction by Non newtonian Additives written by T. Kowalski and published by . This book was released on 1967 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments are described which indicate that a practical use of the so-called non-Newtonian additives may be possible in reducing the viscous drag in full size ships. Until now the huge amounts of additives thought to be required for continuous injection into the boundary layer of water-borne craft precluded the possibility of full scale application except in cases of injections of very short duration. Results of present tests show that additives of the long-chain linear polymer type exhibit a persistence effect and a concentration effect in the boundary layer. It was determined, on the basis of turbulent velocity measurements by means of a hot film sensor, that the effect of polymer injection persisted for some time after the injection was stopped. Pulsing of injection was then developed which produced results similar to continuous injection at an approximate tenfold saving of the additive. From visual observations of injection of polymer and water it became clear that injected polymer concentrated closer to the boundary than similarly injected water. This suggested a possible surface seeking effect of the polymer which produced variation in concentration of additive in the boundary layer and also the above mentioned persistence effect. All the tests indicated that the effect of polymer was greatest when it was concentrated close to the solid boundary. This was confirmed by tests using a number of injection slots from 90 deg to 5 deg inclination to the direction of flow. The 5 deg slot produced an almost tangential injection jet of polymer and was used throughout the experiment. (AUTHOR).

Download or read book Turbulence Control by Passive Means written by E. Coustols and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the 4th European Drag Reduction Meeting