Coherent Structures in Fully Developed Turbulent Pipe Flow PDF Download

Author: Ioannis Constantinos Lekakis
Publisher:
ISBN:
Category : Turbulence
Languages : en
Pages : 504

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Book Description

Author: Zeinab Hallol
Publisher: Cuvillier Verlag
ISBN: 373696501X
Category : Technology & Engineering
Languages : en
Pages : 146

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Book Description
In this thesis, coherent turbulent structures in turbulent pipe flow are investigated at relatively high Reynolds numbers and study their association in both total kinetic energy and Reynolds shear stress. Experimental investigations have been performed in Cottbus Large Pipe test facility (CoLaPipe) for pipe flow over a wide range of Reynolds number 8 × 104 ≤ ReD ≤ 1 × 106, located at the Aerodynamics and Fluid Mechanics Department, Brandenburg University of Technology Cottbus- Senftenberg (BTU). The first part of the thesis focuses on determining the contribution of the coherent structures using one-dimensional spectral analysis and assessing the structures behaviour in the outer region of pipe flow using high spatial resolution Hot-wire measurement up to 30kHz. The results of the power and pre-multiplied spectrum of stream-wise velocity indicate that the wavelength value of very large scale motions (VLSMs) acquires 19R at a maximum Reynolds number range ReD=1 × 106 (Reτ =19000). On the other hand, large-scale motions have a wavelength value of 3R over different Reynolds number range. Regarding the identified wavelength values, it is observed that contribution to energy for structures greater than 3R carries 55% of total kinetic energy. In addition, temporal-spatial resolution using the High-speed PIV measurements has been performed in CoLaPipe to estimate the contribution magnitude of stream-wise/wall-normal velocity fluctuations to total kinetic energy and Reynolds shear stress in the logarithmic and outer layer.

Author: Jean Sabot
Publisher:
ISBN:
Category : Pipe
Languages : en
Pages : 30

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Book Description

Author: Michel Deville
Publisher: Springer Science & Business Media
ISBN: 3642002625
Category : Technology & Engineering
Languages : en
Pages : 166

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Book Description
Contains seven keynote lectures of the TI 2006 conference that was held in Porquerolles, May 29-June 2, 2006. This book offers a view on theory, experiments and numerical simulations in the field of turbulence.

Author: Nadine Aubry
Publisher:
ISBN:
Category : Turbulence
Languages : en
Pages : 344

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Book Description

Author: D. Laurence
Publisher: Elsevier
ISBN: 0080530982
Category : Science
Languages : en
Pages : 975

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Book Description
These proceedings contain the papers presented at the 4th International Symposium on Engineering Turbulence Modelling and Measurements held at Ajaccio, Corsica, France from 24-26 May 1999. It follows three previous conferences on the topic of engineering turbulence modelling and measurements. The purpose of this series of symposia is to provide a forum for presenting and discussing new developments in the area of turbulence modelling and measurements, with particular emphasis on engineering-related problems. Turbulence is still one of the key issues in tackling engineering flow problems. As powerful computers and accurate numerical methods are now available for solving the flow equations, and since engineering applications nearly always involve turbulence effects, the reliability of CFD analysis depends more and more on the performance of the turbulence models. Successful simulation of turbulence requires the understanding of the complex physical phenomena involved and suitable models for describing the turbulent momentum, heat and mass transfer. For the understanding of turbulence phenomena, experiments are indispensable, but they are equally important for providing data for the development and testing of turbulence models and hence for CFD software validation.

Author: J. Westerweel
Publisher:
ISBN:
Category :
Languages : en
Pages : 8

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Book Description
Measurements with particle image velocimetry were carried out in fully developed turbulent pipe flow at a Reynolds number of 5,277. Data were obtained in a plane through the centerline of the pipe, across the full diameter. Statistical properties of the flow obtained by ensemble averaging of the data along the axial direction were in good agreement with direct numerical simulation. Maps of instantaneous tangential vorticity reveal spatial structures near the pipe wall that resemble coherent flow structures predicted by direct numerical simulation. (Author).

Author: Philip Holmes
Publisher: Cambridge University Press
ISBN: 1107008255
Category : Mathematics
Languages : en
Pages : 403

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Book Description
Describes methods revealing the structures and dynamics of turbulence for engineering, physical science and mathematics researchers working in fluid dynamics.

Author: Scherer, Markus Maximilian
Publisher: KIT Scientific Publishing
ISBN: 3731513188
Category :
Languages : en
Pages : 348

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Book Description
The origin of secondary currents and subaqueous sediment patterns in natural rivers is analysed from first principles. For this purpose, simulations of sediment transport in canonical turbulent open channel flows are performed using a numerical technique that resolves all relevant flow scales and the dynamics of the individual sand grains. The high-fidelity datasets reveal the fundamental importance of individual coherent structures for the development of sediment patterns and secondary flows.

Author: O. Métais
Publisher: Springer Science & Business Media
ISBN: 9401579040
Category : Technology & Engineering
Languages : en
Pages : 612

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Book Description
In the last 25 years, one of the most striking advances in Fluid Mecha nics was certainly the discovery of coherent structures in turbulence: lab oratory experiments and numerical simulations have shown that most turbulent flows exhibit both spatially-organized large-scale structures and disorganized motions, generally at smaller scales. The develop ment of new measurement and visualization techniques have allowed a more precise characterization and investigation of these structures in the laboratory. Thanks to the unprecedented increase of computer power and to the development of efficient interactive three-dimensional colour graphics, computational fluid dynamicists can explore the still myste rious world of turbulence. However, many problems remain unsolved concerning the origin of these structures, their dynamics, and their in teraction with the disorganized motions. In this book will be found the latest results of experimentalists, theoreticians and numerical modellers interested in these topics. These coherent structures may appear on airplane wings or slender bodies, mixing layers, jets, wakes or boundary-layers. In free-shear flows and in boundary layers, the results presented here highlight the intense three-dimensional character of the vortices. The two-dimensional large scale eddies are very sensitive to three-dimensional perturbations, whose amplification leads to the formation of three-dimensional coherent vorti cal structures, such as streamwise, hairpin or horseshoe vortex filaments. This book focuses on modern aspects of turbulence study. Relations between turbulence theory and optimal control theory in mathematics are discussed. This may have important applications with regard to, e. g. , numerical weather forecasting.