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Author: Samuel Lortie Publisher: ISBN: Category : Languages : en Pages :
Book Description
"The analysis of turbulence by way of higher-order spectral moments is uncommon, despite the relatively frequent use of such statistical analyses in other fields of physics and engineering. In this work, higher-order spectral moments are used to investigate the internal intermittency of the turbulent velocity and passive scalar (temperature) fields. This research first introduces the theory behind higher-order spectral moments as they pertain to the field of turbulence. Then, a short-time-Fourier-transform-based method is developed to estimate the higher-order spectral moments and provide a relative, scale-by-scale measure of intermittency. Experimental data are subsequently analysed and consist of measurements of homogeneous, isotropic, high-Reynolds-number, passive and active grid turbulence and wall-bounded turbulence (fully developed turbulent channel flow) over Taylor microscale Reynolds numbers between 35 and 731. Emphasis is placed on third- and fourth-order spectral moments using the definitions formalised by Antoni (2006), as such statistics are sensitive to transients and provide insight into deviations from Gaussian behaviour in grid turbulence. The higher-order spectral moments are also used to investigate the Reynolds and Péclet number dependence of the internal intermittency of velocity and passive scalar fields, respectively. The results demonstrate that the evolution of higher-order spectral moments with Reynolds number is strongly dependent on wavenumber. Additionally, the relative levels of internal intermittency of velocity and passive scalar fields are compared and a higher level of internal intermittency in the inertial subrange of the scalar field is consistently observed whereas a similar level of internal intermittency is observed for the velocity and passive scalar fields for the high-Reynolds-numbers-cases as the Kolmogorov length scale is approached. Finally, higher-order spectral moments are shown to display increased levels in the near-wall region of a wall-bounded (channel) flow. The increased intermittent activity is believed to be caused by the presence of coherent structures in wall-bounded flows"--
Author: Samuel Lortie Publisher: ISBN: Category : Languages : en Pages :
Book Description
"The analysis of turbulence by way of higher-order spectral moments is uncommon, despite the relatively frequent use of such statistical analyses in other fields of physics and engineering. In this work, higher-order spectral moments are used to investigate the internal intermittency of the turbulent velocity and passive scalar (temperature) fields. This research first introduces the theory behind higher-order spectral moments as they pertain to the field of turbulence. Then, a short-time-Fourier-transform-based method is developed to estimate the higher-order spectral moments and provide a relative, scale-by-scale measure of intermittency. Experimental data are subsequently analysed and consist of measurements of homogeneous, isotropic, high-Reynolds-number, passive and active grid turbulence and wall-bounded turbulence (fully developed turbulent channel flow) over Taylor microscale Reynolds numbers between 35 and 731. Emphasis is placed on third- and fourth-order spectral moments using the definitions formalised by Antoni (2006), as such statistics are sensitive to transients and provide insight into deviations from Gaussian behaviour in grid turbulence. The higher-order spectral moments are also used to investigate the Reynolds and Péclet number dependence of the internal intermittency of velocity and passive scalar fields, respectively. The results demonstrate that the evolution of higher-order spectral moments with Reynolds number is strongly dependent on wavenumber. Additionally, the relative levels of internal intermittency of velocity and passive scalar fields are compared and a higher level of internal intermittency in the inertial subrange of the scalar field is consistently observed whereas a similar level of internal intermittency is observed for the velocity and passive scalar fields for the high-Reynolds-numbers-cases as the Kolmogorov length scale is approached. Finally, higher-order spectral moments are shown to display increased levels in the near-wall region of a wall-bounded (channel) flow. The increased intermittent activity is believed to be caused by the presence of coherent structures in wall-bounded flows"--
Author: J. C. Vassilicos Publisher: Cambridge University Press ISBN: 9780521792219 Category : Mathematics Languages : en Pages : 292
Book Description
This volume was the product of a workshop held at the Newton Institute in Cambridge, and examines turbulence, intermittency, nonlinear dynamics and fluid mechanics.
Author: Eun-jin Kim Publisher: MDPI ISBN: 3039211080 Category : Mathematics Languages : en Pages : 300
Book Description
This book is a printed edition of the Special Issue Intermittency and Self-Organisation in Turbulence and Statistical Mechanics that was published in Entropy
Author: Yohann Duguet Publisher: MDPI ISBN: 3036509429 Category : Social Science Languages : en Pages : 180
Book Description
This book contains original peer-reviewed articles written by some of the most prominent international physicists active in the field of hydrodynamics. The topic is entirely devoted to the study of the transitional regimes of incompressible viscous flow found at the onset of turbulent flows. Nine articles written for this 2020 Special Issue of the journal Entropy (MDPI) have been gathered at the crossroads of fluid mechanics, statistical physics, complexity theory, and applied mathematics. They include experimental, analytic, and computational material of an academic level that has not been published anywhere else.
Author: Robert Moser Publisher: Elsevier ISBN: 032399833X Category : Science Languages : en Pages : 568
Book Description
Numerical Methods in Turbulence Simulation provides detailed specifications of the numerical methods needed to solve important problems in turbulence simulation. Numerical simulation of turbulent fluid flows is challenging because of the range of space and time scales that must be represented. This book provides explanations of the numerical error and stability characteristics of numerical techniques, along with treatments of the additional numerical challenges that arise in large eddy simulations. Chapters are written as tutorials by experts in the field, covering specific both contexts and applications. Three classes of turbulent flow are addressed, including incompressible, compressible and reactive, with a wide range of the best numerical practices covered. A thorough introduction to the numerical methods is provided for those without a background in turbulence, as is everything needed for a thorough understanding of the fundamental equations. The small scales that must be resolved are generally not localized around some distinct small-scale feature, but instead are distributed throughout a volume. These characteristics put particular strain on the numerical methods used to simulate turbulent flows. Includes a detailed review of the numerical approximation issues that impact the simulation of turbulence Provides a range of examples of large eddy simulation techniques Discusses the challenges posed by boundary conditions in turbulence simulation and provides approaches to addressing them
Author: Erich L. Lehmann Publisher: Springer Science & Business Media ISBN: 0387227288 Category : Mathematics Languages : en Pages : 610
Book Description
This second, much enlarged edition by Lehmann and Casella of Lehmann's classic text on point estimation maintains the outlook and general style of the first edition. All of the topics are updated, while an entirely new chapter on Bayesian and hierarchical Bayesian approaches is provided, and there is much new material on simultaneous estimation. Each chapter concludes with a Notes section which contains suggestions for further study. This is a companion volume to the second edition of Lehmann's "Testing Statistical Hypotheses".
Author: Jean Piquet Publisher: Springer Science & Business Media ISBN: 3662035596 Category : Technology & Engineering Languages : en Pages : 767
Book Description
obtained are still severely limited to low Reynolds numbers (about only one decade better than direct numerical simulations), and the interpretation of such calculations for complex, curved geometries is still unclear. It is evident that a lot of work (and a very significant increase in available computing power) is required before such methods can be adopted in daily's engineering practice. I hope to l"Cport on all these topics in a near future. The book is divided into six chapters, each· chapter in subchapters, sections and subsections. The first part is introduced by Chapter 1 which summarizes the equations of fluid mechanies, it is developed in C~apters 2 to 4 devoted to the construction of turbulence models. What has been called "engineering methods" is considered in Chapter 2 where the Reynolds averaged equations al"C established and the closure problem studied (§1-3). A first detailed study of homogeneous turbulent flows follows (§4). It includes a review of available experimental data and their modeling. The eddy viscosity concept is analyzed in §5 with the l"Csulting ~alar-transport equation models such as the famous K-e model. Reynolds stl"Css models (Chapter 4) require a preliminary consideration of two-point turbulence concepts which are developed in Chapter 3 devoted to homogeneous turbulence. We review the two-point moments of velocity fields and their spectral transforms (§ 1), their general dynamics (§2) with the particular case of homogeneous, isotropie turbulence (§3) whel"C the so-called Kolmogorov's assumptions are discussed at length.
Author: Samuel Lortie
Author: Samuel Lortie
Author: J. C. Vassilicos
Author: Reginald J. Hill
Author: Eun-jin Kim
Author: Yohann Duguet
Author: Robert Moser
Author: Erich L. Lehmann
Author: 
Author: Jean Piquet
Author: United States. National Bureau of Standards