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Numerical Study Of Drag Reduction Through Rotating Actuators In A Wall Bounded Turbulent Flow
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Book Synopsis Numerical Study of Drag Reduction Through Rotating Actuators in a Wall-bounded Turbulent Flow by : Paolo Olivucci
Download or read book Numerical Study of Drag Reduction Through Rotating Actuators in a Wall-bounded Turbulent Flow written by Paolo Olivucci and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Studies of Laminar and Turbulent Drag Reduction by : Ramakrishna Balasubramanian
Download or read book Numerical Studies of Laminar and Turbulent Drag Reduction written by Ramakrishna Balasubramanian and published by . This book was released on 1983 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbulent Drag Reduction by Surfactant Additives by : Feng-Chen Li
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.
Book Synopsis Direct Numerical Simulation of Turbulent Drag Reduction: Molecular Modeling Molecular Optimization and Modeling Without Consititutive Equations by :
Download or read book Direct Numerical Simulation of Turbulent Drag Reduction: Molecular Modeling Molecular Optimization and Modeling Without Consititutive Equations written by and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present numerical simulations of turbulent drag reduction in wall-bounded flows by additives. The bulk of the work concentrates on polymer additives. A multiscale approach was used to study the fine details of polymer dynamics in turbulence and the transfer of energy between polymers and turbulence. It was shown that polymers extract energy from near-wall vortices and release energy in high-speed streaks very close to the wall. We derived a conceptual model which applies to the two, statistically distinct regimes of polymer drag reduction, namely low drag reduction (LDR) and high drag reduction (HDR). Another additive, fibres, was found to obey to a different mechanism which requires close interaction of multiple vortices.
Book Synopsis A Numerical Study on Drag Reduction for Turbulent Transonic Flow Over a Projectile by : J.-K. Fu
Download or read book A Numerical Study on Drag Reduction for Turbulent Transonic Flow Over a Projectile written by J.-K. Fu and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Studies of Laminar and Turbulent Drag Reduction, Part 2 by : R. Balasubramanian
Download or read book Numerical Studies of Laminar and Turbulent Drag Reduction, Part 2 written by R. Balasubramanian and published by . This book was released on 1983 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Drag Reduction in Near-wall Turbulent Flow by : Peter North Blossey
Download or read book Drag Reduction in Near-wall Turbulent Flow written by Peter North Blossey and published by . This book was released on 1999 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Advances in Turbulence XII by : Bruno Eckhardt
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.-
Book Synopsis Drag Reduction of Turbulent Flows by Additives by : A. Gyr
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.
Book Synopsis Numerical Studies of Laminar and Turbulent Drag Reduction by : Ramakrishna Balasubramanian
Download or read book Numerical Studies of Laminar and Turbulent Drag Reduction written by Ramakrishna Balasubramanian and published by . This book was released on 1981 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbulent Drag Reduction by : Haecheon Choi
Download or read book Turbulent Drag Reduction written by Haecheon Choi and published by . This book was released on 1992 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Numerical Study of Turbulent Drag Reduction Using Streamwise Travelling Waves of Spanwise Wall Velocity by : Edward Hurst (Researcher in engineering)
Download or read book A Numerical Study of Turbulent Drag Reduction Using Streamwise Travelling Waves of Spanwise Wall Velocity written by Edward Hurst (Researcher in engineering) and published by . This book was released on 2013 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Structure of Turbulence and Drag Reduction by : Albert Gyr
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 Applied Mechanics Reviews written by and published by . This book was released on 1989 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A numerical study of turbulent drag reduction using streamwise travelling waves of spanwise wall velocity by : Edward Hurst
Download or read book A numerical study of turbulent drag reduction using streamwise travelling waves of spanwise wall velocity written by Edward Hurst and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Geometry Mediated Drag Reduction Using Riblets and Wrinkled Surface Textures by : Shabnam Raayai Ardakani
Download or read book Geometry Mediated Drag Reduction Using Riblets and Wrinkled Surface Textures written by Shabnam Raayai Ardakani and published by . This book was released on 2018 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: The surfaces of many plants and animals are covered with a variety of micro-textures such as ribs or 3D tubules which can control surface-mediated properties such as skin friction. Inspired by the drag reducing ability of these natural structures, especially the ribbed features on shark denticles, passive drag reduction strategies such as micro-fabricated riblet surfaces have been developed and studied. Microgroove textures on the surface of objects such as hulls, wings or inner surface of pipes which are aligned in the stream-wise direction have been shown to reduce the wall friction by 4 − 8%. The mechanisms suggested for this form of drag reduction are viscous retardation of the flow in the grooves (both laminar and turbulent) and the displacement of vortical structures away from the wall in turbulent flows. Due to their effectiveness in altering the boundary layer structure and reducing the viscous drag force, use of riblets have been banned in various competitions such as the America’s Cup. The current thesis work is partly focused on theoretical and numerical modelling (using the open source CFD package OpenFOAM) of the evolution of viscous boundary layers in the presence of various-shaped riblets (V-grooves as well as sinusoidal wrinkled surfaces) in high Reynolds laminar flow. We explore the effect of the dimensionless height to spacing of the grooves (aspect ratio) as well as the length of the wetted surface in the streamwise direction and how these change the total drag compared with a corresponding flat wall. We show that riblets retard the viscous flow inside the grooves and reduce the shear stress inside the grooves. But for this reduction to result in overall drag reduction, the riblet wall needs to be longer than a critical length. The total drag reduction achieved is a non-monotonic function of the aspect ratio of the riblets, with aspect ratios of order unity offering the largest reduction in the total drag. To eliminate the role of entrance effects, we additionally investigate the effect of stream-wise aligned riblet structures on fully-developed Taylor-Couette flow. We perform both experimental studies as well as time-dependent numerical simulations in both the laminar Couette and the Taylor vortex regime. We again explore the effect of the size of the riblets with respect to the geometry of the Taylor-Couette cell, as well as the aspect ratio of the riblet grooves and the shape of the grooves (V-groove, Rectangular, semi-circular, etc.). For the experiments, the cylindrical textured rotors are fabricated using 3D printing techniques and the rest of the Taylor-Couette cell is custom built using CNC machining. The test cell is then aligned and mounted on a stress-controlled rheometer to measure the velocity and the torque on the rotating inner cylinder. The numerical studies are performed using the open source CFD software package OpenFOAM to compare results and understand the physical mechanisms contributing to this drag reduction phenomenon. Again we observe a non-monotonic behavior for the reduction in torque as a function of the aspect ratio of the riblets tested, similar to the trend observed in the boundary layer analysis and we discuss the effect of changing the geometry of the flow as well as the riblet spacing on the changes in the total torque. When viewed holistically the results of these two studies show that, through careful design, a net reduction in viscous drag force can be robustly realized on micro-textured surfaces in high Reynolds number laminar flows through complex changes in near-wall stream-wise velocity profiles even in the absence of turbulent effects. The understanding of these changes can be effective in guiding the design of internal flows (pipes or ducts) and external flows (such as ship hulls, micro air vehicles or unmanned underwater vehicles) that are tailored and optimized to result in low frictional drag over the entire wetted surface in both laminar and turbulent regions.
Book Synopsis Numerical Studies of Laminar and Turbulent Drag Reduction by : R. Balasubramanian
Download or read book Numerical Studies of Laminar and Turbulent Drag Reduction written by R. Balasubramanian and published by . This book was released on 1981 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
