Download or read book Experimental Investigations Into the Transitions to Turbulence in Newtonian and Drag reducing Polymeric Taylor Couette Flows written by Cari Suzanne Dutcher and published by . This book was released on 2009 with total page 586 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transition and Turbulence written by Richard E. Meyer and published by Academic Press. This book was released on 2014-05-10 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mathematics Research Center Symposia and Advanced Seminar Series: Transition and Turbulence covers the lectures presented at the Symposium on Transition and Turbulence in Fluids, held in Madison, Wisconsin on October 13-15, 1980 under the auspices of the Mathematics Research Center of the University of Wisconsin-Madison. The book focuses on the relation between transition and turbulence in fluids and the importance of this relation for the understanding of many real fluid motions. The selection first elaborates on transition in flow between rotating concentric cylinders, observations in the Taylor experiment, and transition to turbulence in thermal convection with and without rotation. Discussions focus on low aspect ratio convection layers, random convection in a rotating layer, unsteady flows at high Reynolds numbers, transition to oscillatory motion, and experimental observations. The text then tackles instability and turbulence in jets, instability and transition in pipes and channels, and transition to turbulence in boundary layers. The book ponders on coherent structures in turbulence; interactions between large-scale coherent structures and fine-grained turbulence in free shear flows; and vortex interactions and coherent structures in turbulence. Topics include atomic and molecular representations, vortices in uniform strain, vortex pairs, numerical computations applied to a simple problem, agglomeration of large-scale structures and subharmonic formation, retrieving phase information, and dynamical equations. The selection is highly recommended for researchers interested in pursuing further studies on transition and turbulence.
Download or read book A Review of Approaches to the Study of Turbulence Modification by Means of Non Newtonian Additives written by Dimitris Vlassopoulos and published by . This book was released on 1987 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: The addition of small amounts of polymers to Newtonian liquids under conditions of turbulent flow results in substantial reduction of skin friction. This phenomenon has been observed experimentally. It can be attributed to the unusual behavior of dilute polymer solutions in turbulent flows. A condensed review of topics relevent to theoretical study of drag reduction by non-Newtonian additives is presented. In addition, the techniques and results of experimental investigations of this phenomenon are examined. It is proposed that dilute solutions of polymers or surfactants can be rheologically characterized by measuring the secondary flow characteristics that occur in the neighborhood of an oscillating cylinder. Plans for conducting these measurements are presented. Keywords: Drag reduction; Turbulence modifications; Rheology; Non-Newtonian fluid mechanics; Viscoelastic liquids; Polymers; Surfactants.
Download or read book Advances in Turbulence XII written by Bruno Eckhardt and published by Springer. This book was released on 2016-09-27 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lagrangian aspects.- Lagrangian modeling and properties of particles with inertia.- Effect of Faxén forces on acceleration statistics of material particles in turbulent flow.- Lagrangian analysis of turbulent convection.- Linear and angular dynamics of an inertial particle in turbulence.- Collision rate between heavy particles in a model turbulent flow.- From cloud condensation nuclei to cloud droplets: a turbulent model.- Lagrangian statistics of inertial particles in turbulent flow.- Lagrangian statistics of two–dimensional turbulence in a square container.- Measurement of Lagrangian Particle Trajectories by Digital in-line Holography.- 3-D Particle Tracking Velocimetry (PTV) in gas flows using coloured tracer particles.- Two-particle dispersion in 2D inverse cascade turbulence and its telegraph equation model.- Numerical simulations of particle dispersion in stratified flows.- Instability and Transition.- Experimental study of the von Kármán flow from = 10 to 10: spontaneous symmetry breaking and turbulent bifurcations.- Flow reversals in a vertical channel.- Linear Instability of Streamwise Corner Flow.- DNS of turbulent plane Couette flow with emphasis on turbulent stripe.- Geometry of state space in plane Couette flow.- Linear and nonlinear instabilities of sliding Couette flow.- Localization in plane Couette edge dynamics.- Nonlinear optimal perturbations in plane Couette flow.- Order parameter in laminar-turbulent patterns.- Pattern formation in low Reynolds number plane Couette flow.- Quasi-stationary and chaotic convection in low rotating spherical shells.- Linear stability of 2D rough channels.- Transient turbulent bursting in enclosed flows.- On New Localized Vortex Solutions in the Couette-Ekman Layer.- Shear instabilities in Taylor-Couette flow.- Particle Tracking Velocimetry in Transitional Plane Couette Flow.- Experimental study of coherent structures in turbulent pipe flow.- Forced localized turbulence in pipe flows.- From localized to expanding turbulence.- Influence of test-rigs on the laminar-to-turbulent transition of pipe flows.- Interaction of turbulent spots in pipe flow.- Large-scale transitional dynamics in pipe flow.- Nonlinear coherent structures in a square duct.- Quantitative measurement of the life time of turbulence in pipe flow.- Experimental investigation of turbulent patch evolution in spatially steady boundary layers.- Interaction of noise disturbances and streamwise streaks.- Linear generation of multiple time scales by 3D unstable perturbations.- Convection at very high Rayleigh number: signature of transition from a micro-thermometer inside the flow.- Estimating local instabilities for irregular flows in the differentially heated rotating annulus.- Search for the “ultimate state” in turbulent Rayleigh-Bénard convection.- Rayleigh–Taylor instability in two dimensions and phase-field method.- Split energy cascade in quasi-2D turbulence.- Stabililty and laminarisation of turbulent rotating channel flow.- The vortical flow pattern exhibited by the channel flow on a rotating system just past transition under the influence of the Coriolis force.- Transient evolution and high stratification scaling in horizontal mixing layers.- Control of turbulent flows.- Toward cost-effective Control of Wall Turbulence for Skin Friction Drag Reduction.- Active control of turbulent boundary layer using an array of piezo-ceramic actuators.- Flat plate turbulent boundary-layer control using vertical LEBUs.- Estimation of the spanwise wall shear stress based on upstream information for wall turbulence control.- Interactions between vortex generators and a flat plate boundary layer. Application to the control of separated flows..- Modulated global mode of a controlled wake.- Swirl effects in turbulent pipe flow.- Control of an axisymmetric turbulent wake by a pulsed jet.- Direct Numerical Simulations of turbulent mixed convection in enclosures with heated obstacles.-
Download or read book Nonlinear Waves and Pattern Dynamics written by Nizar Abcha and published by Springer. This book was released on 2018-04-20 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the fascinating phenomena associated with nonlinear waves and spatio-temporal patterns. These appear almost everywhere in nature from sand bed forms to brain patterns, and yet their understanding still presents fundamental scientific challenges. The reader will learn here, in particular, about the current state-of-the art and new results in: Nonlinear water waves: resonance, solitons, focusing, Bose-Einstein condensation, as well as and their relevance for the sea environment (sea-wind interaction, sand bed forms, fiber clustering) Pattern formation in non-equilibrium media: soap films, chimera patterns in oscillating media, viscoelastic Couette-Taylor flow, flow in the wake behind a heated cylinder, other pattern formation. The editors and authors dedicate this book to the memory of Alexander Ezersky, Professor of Fluid Mechanics at the University of Caen Normandie (France) from September 2007 to July 2016. Before 2007, he had served as a Senior Scientist at the Institute of Applied Physics of the Russian Academy of Sciences in Nizhny Novgorod (Russia). The chapters have been written by leading scientists in Nonlinear Physics, and the topics chosen so as to cover all the fields to which Prof. Ezersky himself contributed, by means of experimental, theoretical and numerical approaches. The volume will appeal to advanced students and researchers studying nonlinear waves and pattern dynamics, as well as other scientists interested in their applications in various natural media.
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 An Experimental Investigation on Turbulent Plane Couette Flow in Dilute Polymer Solutions written by S. H. Chue and published by . This book was released on 1969 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1967 with total page 742 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Study of Polymer Drag Reduction and Boundary Layer Diffusion Characteristics for Incompressible Flow Over a Flat Plate written by John Miguel and published by . This book was released on 1978 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drag reduction by injection of high molecular weight polymers into boundary layers has been demonstrated repeatedly in the past. However, from a volume utilization tradeoff standpoint, the quantities of polymer required make the gains achieved by this process marginal. While indicating reduced polymer requirements for drag reduction, limited data obtained from pipe flow and external boundary layer flow experiments are conflicting and hard to interpret. Ambiguities in measurement techniques due to polymer effects on commonly used instrumentation and opposing features of varied flow facilities have also contributed to making these earlier works contradictory and difficult to resolve. Experiments performed in this research indicate that turbulence intensity distributions are altered by the addition of polymer in such a way that the peak of turbulence production is lowered and its location moved away from the wall. The transition region is delayed and extended by the addition of polymer to the boundary layer. The laminar sublayer of boundary layer profiles appears to have thickened due to the addition of polymer. When compared to the law of the wall corrected for developing flow, the velocity profiles also show evidence of a thickened sublayer.
Download or read book Viscous Drag Reduction written by C. Sinclair Wells and published by . This book was released on 1969 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effect of Drag Reducing Polymer Additives on Taylor Couette Flows written by Steve Hon-Keung Lee and published by . This book was released on 1990 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Further Developments in Turbulence Management written by K. Krishna Prasad and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: The thrust of modern research on turbulence in fluids is concerned with coherent structures and modelling. Riblets have been shown to reduce drag, and the papers presented in this volume tackle the main question of the mechanism responsible for this behaviour in turbulent flow. The contributions in this volume were presented at the Sixth Drag Reduction Meeting held at Eindhoven during November 1991. This volume will be a useful reference work for engineers, physicists and applied mathematicians interested in the topic of fluid turbulence.
Download or read book Transition to Turbulence written by Tapan K. Sengupta and published by Cambridge University Press. This book was released on 2021-09-30 with total page 643 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Present understanding of transition to turbulence has now been studied over one hundred and fifty years. The path the studies have taken posed it as a modal eigenvalue problem. Some researchers have suggested alternative models without being specific. First-principle based approach of receptivity is the route to build bridges among ideas for solving the Navier-Stokes equation for specific canonical problems. This book highlights the mathematical physics, scientific computing, and new ideas and theories for nonlinear analyses of fluid flows, for which vorticity dynamics remain central. This book is a blend of classic with distinctly new ideas, which establish different dynamics of flows, from genesis to evolution of disturbance fields with rigorously developed methods to tracing coherent structures amidst the seemingly random and chaotic fluid dynamics of transitional and turbulent flows"--
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analytical and Experimental Study of Turbulent Flow Drag Reduction and Degradation with Polymer Additives written by Xin Zhang and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Journal of Basic Engineering written by and published by . This book was released on 1972 with total page 982 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Study of Turbulence Levels Generated with a Taylor Couette Apparatus written by Margaret Elizabeth Solomon and published by . This book was released on 1995 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:
