Effect of Background Turbulence on the Scalar Field of a Turbulent Jet

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Book Synopsis Effect of Background Turbulence on the Scalar Field of a Turbulent Jet by : Alejandro Perez Alvarado

Download or read book Effect of Background Turbulence on the Scalar Field of a Turbulent Jet written by Alejandro Perez Alvarado and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The effect of background turbulence on the scalar field of an axisymmetric turbulent jet is investigated experimentally. The present investigation builds on the work of Gaskin et al. (2004), who studied the concentration and velocity fields of a plane jet in a shallow coflow with different turbulence levels and Khorsandi et al. (2013), who studied the velocity field of an axisymmetric turbulent jet emitted into a turbulent background. Different driving algorithms for a large RJA were tested and the statistics of the turbulence generated downstream of the RJA were compared to characterize the algorithms' performance. Variations in the spatial configuration of jets operating at any given instant, as well as in the statistics of their on/off times were studied. The algorithm identified as RANDOM generated the closest approximation of zero-mean-flow homogeneous isotropic turbulence. The flow generated by the RANDOM algorithm had a relatively high turbulent Reynolds number (ReT = uTl/[nu] = 2360, where uT is a characteristic RMS velocity, l is the integral length scale of the flow, [nu] is the kinematic viscosity of the water) and the integral length scale (l = 11.6 cm) is the largest reported to date. Thus, RANDOM algorithm was used to generate the background turbulence for the investigation of scalar mixing within a turbulent jet.The effect of background turbulence on the mixing of a passive scalar within a turbulent jet at different Reynolds numbers was investigated. To this end, planar laser-induced fluorescence was employed to obtain concentration measurements of dye (disodium fluorescein, Schmidt number = 2000) within the jet. Two jet Reynolds numbers (Re=UjD/[nu], where Uj is the jet exit velocity, D is the nozzle diameter and [nu] is the kinematic viscosity of the jet fluid, water) were studied: 10600 and 5800. The resulting statistics of the scalar fields showed that the mean concentrations of jets emitted into turbulent backgrounds were lower than those of jets emitted into a quiescent background near the centerline. However, near the edges of the jet (r/x>0.15), the concentrations were higher for the jets issued into turbulent surroundings. The RMS concentrations of the jet emitted into a turbulent background significantly increased. Examination of the probability density functions of concentration revealed a higher degree of intermittency of the scalar field. The probability of low concentrations increased in the presence of background turbulence although the maximum concentrations were comparable to those of the jet emitted into a quiescent background. Flow visualizations revealed meandering of the jet issued into background turbulence, which is associated with the increased probability of lower concentrations and higher intermittency. Additionally, the widths of the jets emitted into a turbulent background were increased. For the lower jet Reynolds number, the described effects were more evident and the jet structure was destroyed by the background turbulence within the measurement region, resulting in flat radial profiles of both the mean and RMS concentrations. Comparison of the results of the scalar field with those of the hydrodynamic jet of Khorsandi et al. (2013) revealed a similar behavior of the two fields. However, the most significant difference was the larger radial extent of the profiles of mean and RMS concentrations, which resulted from the meandering of the jet and increased transport of scalar by turbulent diffusion. The flow visualizations suggest that the entrainment and mixing in the jet in a turbulent background changes with the destruction of jet structure, from jet driven entrainment to become potentially dominated by i) increased lateral advection of the jet by large scales of the background turbulence during the meandering of the jet, which is subsequently mixed by its smaller scales, and ii) turbulent diffusion that is significantly enhanced by the turbulent background." --

Decomposition of the Scalar Field in a Turbulent Jet Flow

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ISBN 13 : 9783844018301
Total Pages : 0 pages
Book Rating : 4.0/5 (183 download)

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Book Synopsis Decomposition of the Scalar Field in a Turbulent Jet Flow by : Markus Matthias Gampert

Download or read book Decomposition of the Scalar Field in a Turbulent Jet Flow written by Markus Matthias Gampert and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

The Dynamics of an Axisymmetric Turbulent Jet and of a Passive Scalar Patch in Ambient Turbulence Interpreted from the Passive Scalar Field Statistics

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Book Synopsis The Dynamics of an Axisymmetric Turbulent Jet and of a Passive Scalar Patch in Ambient Turbulence Interpreted from the Passive Scalar Field Statistics by : Rana Sahebjam

Download or read book The Dynamics of an Axisymmetric Turbulent Jet and of a Passive Scalar Patch in Ambient Turbulence Interpreted from the Passive Scalar Field Statistics written by Rana Sahebjam and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The passive scalar field of an axisymmetric turbulent jet and an isokinetic jet in an approximately homogeneous isotropic turbulence (HIT) with negligible mean flow is studied experimentally. The present research builds on that of Khorsandi et al. 2013 and Perez-Alvarado 2016, who studied the velocity field and the passive scalar field of an axisymmetric turbulent jet in a turbulent ambient, respectively. The primary objective is to deduce the jet structure, and to study the jet mixing in the HIT ambient by following the meandering path of the jet, i.e. conditional on the jet centroid. The secondary objective, complementing the first, is to study the diffusion of a momentumless patch of a passive scalar in the HIT ambient.The effect of a turbulent ambient on the dynamics and mixing of the passive scalar field of an axisymmetric turbulent jet is investigated. The experiments were conducted either in a quiescent or a turbulent ambient. The turbulent ambient was generated by a random jet array to achieve an approximately zero-mean-flow HIT ambient in the measurement plane. Two jet Reynolds numbers of Re = 5800 and 10600 were studied. Planar laser-induced fluorescence was used to measure the concentrations of the passive scalar dye (Sc = 2000) at orthogonal cross-sections of the jet at axial distances of x/d = 20, 30, 40, 50, 60. The statistics of the passive scalar field were conditioned on the jet centroid and were compared to the Eulerian statistics and to those of the jet in a quiescent ambient. The use of the centroidal analysis allowed the structure of the jet in the HIT ambient to be deduced, for which a two-region model was proposed. In the first region, following the developing region of the jet, the ambient turbulence progressively disrupts the jet structure and results in a faster concentration decay compared to the quiescent ambient. At a critical downstream distance, where the relative turbulence intensity between the ambient and the jet (ξ = urms,HIT/ urms,jet ) exceeds 0.5, the HIT ambient has destroyed the jet structure and the second region starts. In the second region, the turbulent diffusion is the only mechanism to transport the passive scalar field. The first-order centroidal statistics of the scalar field show self-similarity and self-preservation before jet break-up. The width of the jet is larger in the HIT ambient compared to that in a quiescent ambient and grows with axial distance but remains unchanged beyond jet break-up. Using the present passive scalar data and the velocity data from Khorsandi et al. 2013, it is argued that the momentum-driven entrainment of the jet in the HIT ambient is reduced compared to that in a quiescent ambient, and that the entrainment ceases beyond the jet break-up. The entrainment of the smaller scales of the ambient turbulence leads to a wider range of centerline concentrations and rms concentrations within the jet, and they are hypothesized to increase local concentration gradients and reduce the jet mixing.Diffusion of a patch of a passive scalar in the HIT ambient is studied. A high-Sc number passive scalar dye (Sc = 2500) is released isokinetically from a large diameter jet (d = 29.97 mm), and an orthogonal view of the passive scalar field is obtained using planar laser-induced fluorescence. The temporal evolution of the scalar patch is due to molecular diffusion and to turbulent diffusion in a quiescent ambient and in the HIT ambient, respectively. Time-averaged statistics of the passive scalar field are assessed at t = 0.2, 1, 1.8, 2.6, 3.4 s using a centroidal analysis. The mean concentration decays quickly and the rms concentration increases within the scalar patch. Compared to the quiescent ambient case, a wider range of the concentrations is present at the centroid of the scalar field. The size of the scalar patch increases with time, which is attributed to an increasing turbulent diffusivity for times shorter than the integral time scale of the turbulence"--

Effect of Background Turbulence on an Axisymmetric Turbulent Jet

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ISBN 13 : 9780494786505
Total Pages : pages
Book Rating : 4.7/5 (865 download)

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Book Synopsis Effect of Background Turbulence on an Axisymmetric Turbulent Jet by : Babak Khorsandi

Download or read book Effect of Background Turbulence on an Axisymmetric Turbulent Jet written by Babak Khorsandi and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Turbulent Flow

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Publisher : John Wiley & Sons
ISBN 13 : 0471275387
Total Pages : 512 pages
Book Rating : 4.4/5 (712 download)

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Book Synopsis Turbulent Flow by : Peter S. Bernard

Download or read book Turbulent Flow written by Peter S. Bernard and published by John Wiley & Sons. This book was released on 2002-11-14 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides unique coverage of the prediction and experimentationnecessary for making predictions. Covers computational fluid dynamics and its relationship todirect numerical simulation used throughout the industry. Covers vortex methods developed to calculate and evaluateturbulent flows. Includes chapters on the state-of-the-art applications ofresearch such as control of turbulence.

Recent Research Advances in the Fluid Mechanics of Turbulent Jets and Plumes

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Publisher : Springer Science & Business Media
ISBN 13 : 9401109184
Total Pages : 513 pages
Book Rating : 4.4/5 (11 download)

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Book Synopsis Recent Research Advances in the Fluid Mechanics of Turbulent Jets and Plumes by : P.A. Davies

Download or read book Recent Research Advances in the Fluid Mechanics of Turbulent Jets and Plumes written by P.A. Davies and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 513 pages. Available in PDF, EPUB and Kindle. Book excerpt: Challenging problems involvrllg jet and plume phenomena are common to many areas of fundamental and applied scientific research, and an understanding of plume and jet behaviour is essential in many geophysical and industrial contexts. For example, in the field of meteorology, where pollutant dispersal takes place by means of atmospheric jets and plumes formed either naturally under conditions of convectively-driven flow in the atmospheric boundary layer, or anthropogenically by the release of pollutants from tall chimneys. In other fields of geophysics, buoyant plumes and jets are known to play important roles in oceanic mixing processes, both at the relatively large scale (as in deep water formation by convective sinking) and at the relatively small scale (as with plume formation beneath ice leads, for example). In the industrial context, the performances of many engineering systems are determined primarily by the behaviour of buoyant plumes and jets. For example, (i) in sea outfalls, where either sewage or thermal effluents are discharged into marine and/or freshwater environments, (ii) in solar ponds, where buoyant jets are released under density interfaces, (iii) in buildings, where thermally-generated plumes affect the air quality and ventilation properties of architectural environments, (iv) in rotating machinery where fluid jet~ are used for cooling purposes, and (v) in long road and rail tunnels, where safety and ventilation prcedures rely upon an understanding of the behaviour of buoyant jets. In many other engineering and oceanographic contexts, the properties of jets and plumes are of great importance.

Scientific and Technical Aerospace Reports

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ISBN 13 :
Total Pages : 464 pages
Book Rating : 4.:/5 (3 download)

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Book Synopsis Scientific and Technical Aerospace Reports by :

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Examining the Effects of a Controled Turbulent Velocity Field on a Passive Scalar

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ISBN 13 :
Total Pages : 79 pages
Book Rating : 4.:/5 (795 download)

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Book Synopsis Examining the Effects of a Controled Turbulent Velocity Field on a Passive Scalar by : Don O'Regan

Download or read book Examining the Effects of a Controled Turbulent Velocity Field on a Passive Scalar written by Don O'Regan and published by . This book was released on 2005 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Progress in Turbulence IX

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Publisher : Springer Nature
ISBN 13 : 3030807169
Total Pages : 308 pages
Book Rating : 4.0/5 (38 download)

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Book Synopsis Progress in Turbulence IX by : Ramis Örlü

Download or read book Progress in Turbulence IX written by Ramis Örlü and published by Springer Nature. This book was released on 2021-10-23 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume collects the edited and reviewed contribution presented in the 9th iTi Conference that took place virtually, covering fundamental and applied aspects in turbulence. In the spirit of the iTi conference, the volume is produced after the conference so that the authors had the opportunity to incorporate comments and discussions raised during the meeting. In the present book, the contributions have been structured according to the topics: I Experiments II Simulations and Modelling III Data Processing and Scaling IV Theory V Miscellaneous topics

Turbulent Jets

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Publisher : Elsevier
ISBN 13 : 0080869963
Total Pages : 315 pages
Book Rating : 4.0/5 (88 download)

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Book Synopsis Turbulent Jets by : N. Rajaratnam

Download or read book Turbulent Jets written by N. Rajaratnam and published by Elsevier. This book was released on 1976-01-01 with total page 315 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent Jets

Applied Mechanics Reviews

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ISBN 13 :
Total Pages : 796 pages
Book Rating : 4.:/5 (26 download)

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Book Synopsis Applied Mechanics Reviews by :

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1970 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Turbulence in the Solar Wind

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Publisher : Springer
ISBN 13 : 3319434403
Total Pages : 270 pages
Book Rating : 4.3/5 (194 download)

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Book Synopsis Turbulence in the Solar Wind by : Roberto Bruno

Download or read book Turbulence in the Solar Wind written by Roberto Bruno and published by Springer. This book was released on 2016-10-07 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an overview of solar wind turbulence from both the theoretical and observational perspective. It argues that the interplanetary medium offers the best opportunity to directly study turbulent fluctuations in collisionless plasmas. In fact, during expansion, the solar wind evolves towards a state characterized by large-amplitude fluctuations in all observed parameters, which resembles, at least at large scales, the well-known hydrodynamic turbulence. This text starts with historical references to past observations and experiments on turbulent flows. It then introduces the Navier-Stokes equations for a magnetized plasma whose low-frequency turbulence evolution is described within the framework of the MHD approximation. It also considers the scaling of plasma and magnetic field fluctuations and the study of nonlinear energy cascades within the same framework. It reports observations of turbulence in the ecliptic and at high latitude, treating Alfvénic and compressive fluctuations separately in order to explain the transport of mass, momentum and energy during the expansion. Further, existing models are compared with direct observations in the heliosphere. The problem of self-similar and anomalous fluctuations in the solar wind is then addressed using tools provided by dynamical system theory and discussed on the basis of available models and observations. The book highlights observations of Yaglom’s law in solar wind turbulence, which is one of the most important findings in fully developed turbulence and directly related to the long-lasting and still unsolved problem of solar wind plasma heating. Lastly, it includes a short chapter dedicated to the kinetic range of fluctuations, which has recently been receiving more attention from the space plasma community, since this is inherently related to turbulent energy dissipation and consequent plasma heating. It particularly focuses on the nature and role of the fluctuations populating this frequency range, and discusses several model predictions and recent observational findings in this context.

Injection and Mixing in Turbulent Flow

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ISBN 13 :
Total Pages : 232 pages
Book Rating : 4.F/5 ( download)

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Book Synopsis Injection and Mixing in Turbulent Flow by : Joseph A. Schetz

Download or read book Injection and Mixing in Turbulent Flow written by Joseph A. Schetz and published by . This book was released on 1980 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Good,No Highlights,No Markup,all pages are intact, Slight Shelfwear,may have the corners slightly dented, may have slight color changes/slightly damaged spine.

Turbulent Jets and Plumes

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Publisher : Springer Science & Business Media
ISBN 13 : 1461504074
Total Pages : 391 pages
Book Rating : 4.4/5 (615 download)

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Book Synopsis Turbulent Jets and Plumes by : Joseph Hun-wei Lee

Download or read book Turbulent Jets and Plumes written by Joseph Hun-wei Lee and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: Jets and plumes are shear flows produced by momentum and buoyancy forces. Examples include smokestack emissions, fires and volcano eruptions, deep sea vents, thermals, sewage discharges, thermal effluents from power stations, and ocean dumping of sludge. Knowledge of turbulent mixing by jets and plumes is important for environmental control, impact and risk assessment. Turbulent Jets and Plumes introduces the fundamental concepts and develops a Lagrangian approach to model these shear flows. This theme persists throughout the text, starting from simple cases and building towards the practically important case of a turbulent buoyant jet in a density-stratified crossflow. Basic ideas are illustrated by ample use of flow visualization using the laser-induced fluorescence technique. The text includes many illustrative worked examples, comparisons of model predictions with laboratory and field data, and classroom tested problems. An interactive PC-based virtual-reality modelling software (VISJET) is also provided. Engineering and science students, researchers and practitioners may use the book both as an introduction to the subject and as a reference in hydraulics and environmental fluid mechanics.

Dissertation Abstracts International

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ISBN 13 :
Total Pages : 644 pages
Book Rating : 4.F/5 ( download)

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Book Synopsis Dissertation Abstracts International by :

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2003 with total page 644 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Theories of Turbulence

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Publisher : Springer
ISBN 13 : 3709125642
Total Pages : 377 pages
Book Rating : 4.7/5 (91 download)

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Book Synopsis Theories of Turbulence by : Martin Oberlack

Download or read book Theories of Turbulence written by Martin Oberlack and published by Springer. This book was released on 2014-05-04 with total page 377 pages. Available in PDF, EPUB and Kindle. Book excerpt: The term "turbulence” is used for a large variety of dynamical phenomena of fluids in motion whenever the details of the flow appear to be random and average properties are of primary interest. Just as wide ranging are the theoretical methods that have been applied towards a better understanding of fluid turbulence. In this book a number of these methods are described and applied to a broad range of problems from the transition to turbulence to asymptotic turbulence when the inertial part of the spectrum is fully developed. Statistical as well as nonstatistical treatments are presented, but a complete coverage of the subject is not attempted. The book will be of interest to scientists and engineers who wish to familiarize themselves with modern developments in theories of turbulence. The fact that the properties of turbulent fluid flow are addressed from very different points of view makes this volume rather unique among presently available books on turbulence.

The 1992 NASA Langley Measurement Technology Conference

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ISBN 13 :
Total Pages : 448 pages
Book Rating : 4.:/5 (317 download)

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Book Synopsis The 1992 NASA Langley Measurement Technology Conference by : Jag J. Singh

Download or read book The 1992 NASA Langley Measurement Technology Conference written by Jag J. Singh and published by . This book was released on 1992 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: