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Author : Yifei Yu
Publisher : Springer Nature
ISBN 13 : 3031536703
Total Pages : 201 pages
Book Rating : 4.0/5 (315 download)
Download or read book Mechanism of Hairpin Vortex Formation by Liutex written by Yifei Yu and published by Springer Nature. This book was released on with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Chaoqun Liu
Publisher : Springer Nature
ISBN 13 : 3030702170
Total Pages : 479 pages
Book Rating : 4.0/5 (37 download)
Download or read book Liutex and Third Generation of Vortex Definition and Identification written by Chaoqun Liu and published by Springer Nature. This book was released on 2021-07-26 with total page 479 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book collects papers presented in the Invited Workshop, “Liutex and Third Generation of Vortex Definition and Identification for Turbulence,” from CHAOS2020, June 9-12, 2020, which was held online as a virtual conference. Liutex is a new physical quantity introduced by Prof. Chaoqun Liu of the University of Texas at Arlington. It is a vector and could give a unique and accurate mathematical definition for fluid rotation or vortex. The papers in this volume include some Liutex theories and many applications in hydrodynamics, aerodynamics and thermal dynamics including turbine machinery. As vortex exists everywhere in the universe, a mathematical definition of vortex or Liutex will play a critical role in scientific research. There is almost no place without vortex in fluid dynamics. As a projection, the Liutex theory will play an important role on the investigations of the vortex dynamics in hydrodynamics, aerodynamics, thermodynamics, oceanography, meteorology, metallurgy, civil engineering, astronomy, biology, etc. and to the researches of the generation, sustenance, modelling and controlling of turbulence.
Author : Sita Charkrit
Publisher :
ISBN 13 :
Total Pages : 171 pages
Book Rating : 4.:/5 (132 download)
Download or read book Liutex Analysis by Pod and DMD for Vortex Formations in Boundary Layer Transition written by Sita Charkrit and published by . This book was released on 2020 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vortices are considered as the building blocks of turbulent flows. To study how one type of vortex becomes another type especially in flow transition is one way to get better understanding about turbulence. In this dissertation, two types of vortex formations, i.e., the hairpin vortex formation and the formation of vortex structure from symmetry to asymmetry, are studied by the direct numerical simulation. According to Liu et al. (2019), Liutex has been proposed as a new physical quantity with scalar, vector and tensor forms. A Liutex vector is defined as a rotation part of fluid motion without shear contamination. The purpose of this work is to apply Liutex and other Liutex-based methods to analyze and identify the vortex structures in the flow transition. Moreover, the proper orthogonal decomposition and dynamic mode decomposition are applied to extract the whole structures into coherent structures. In this work, the hairpin vortex formation in early transition is analyzed by the new mathematical definition of vortex core based Liutex definition. The results apparently show that the Lambda vortex is not self-deformed to the hairpin vortex as many literatures suggested. Then, the POD result demonstrates that fluctuating modes are in pairs and share the same characteristics such as eigenvalues, eigenvectors, amplitudes, mode shapes and time evolutions. It can be implied that the Lambda vortex is not self deformed to a hairpin vortex, but it is formed by the K-H instability during the formation of Lambda vortex and hairpin vortex in boundary layer flow transition. In addition, in late flow transition, which is more complex than the early stage, the symmetric and asymmetric areas are compared to identify the vortex structures. The new findings from Liutex analysis are obtained as follows. 1) Asymmetry of vortex structure starts from the bottom not the middle or the top part of wall normal direction. 2) Asymmetry of vortex structure is measured strong in the bottom, moderate in the middle and weak on the top.3) Flow fluctuations are closely related to the Liutex or fluid rotation. 4) Flow fluctuations are closely correlated with the loss of symmetry of vortex structures. 5) The high frequency modes represent small-scale structures. 6) The low-frequency modes that possess the high Liutex magnitudes represent large-scale structures of hairpin vortices, whereas the low-frequency modes that possess the low Liutex magnitudes represent large-scale structures of streamwise vortices.
Author : Chaoqun Liu
Publisher : Academic Press
ISBN 13 : 0128190248
Total Pages : 458 pages
Book Rating : 4.1/5 (281 download)
Download or read book Liutex and Its Applications in Turbulence Research written by Chaoqun Liu and published by Academic Press. This book was released on 2020-10-29 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liutex and Its Applications in Turbulence Research reviews the history of vortex definition, provides an accurate mathematical definition of vortices, and explains their applications in flow transition, turbulent flow, flow control, and turbulent flow experiments. The book explains the term "Rortex" as a mathematically defined rigid rotation of fluids or vortex, which could help solve many longstanding problems in turbulence research. The accurate mathematical definition of the vortex is important in a range of industrial contexts, including aerospace, turbine machinery, combustion, and electronic cooling systems, so there are many areas of research that can benefit from the innovations described here. This book provides a thorough survey of the latest research in generalized and flow-thermal, unified, law-of-the-wall for wall-bounded turbulence. Important theory and methodologies used for developing these laws are described in detail, including: the classification of the conventional turbulent boundary layer concept based on proper velocity scaling; the methodology for identification of the scales of velocity, temperature, and length needed to establish the law; and the discovery, proof, and strict validations of the laws, with both Reynolds and Prandtl number independency properties using DNS data. The establishment of these statistical laws is important to modern fluid mechanics and heat transfer research, and greatly expands our understanding of wall-bounded turbulence. Provides an accurate mathematical definition of vortices Provides a thorough survey of the latest research in generalized and flow-thermal, unified, law-of-the-wall for wall-bounded turbulence Explains the term “Rortex as a mathematically defined rigid rotation of fluids or vortex Covers the statistical laws important to modern fluid mechanics and heat transfer research, and greatly expands our understanding of wall-bounded turbulence
Author : Yiqian Wang
Publisher : Springer Nature
ISBN 13 : 9811989559
Total Pages : 421 pages
Book Rating : 4.8/5 (119 download)
Download or read book Liutex and Third Generation of Vortex Identification written by Yiqian Wang and published by Springer Nature. This book was released on 2023-03-21 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings highlights the applications of the newly introduced physical quantity Liutex in hydrodynamics and aerodynamics. Liutex is used to represent the fascinating rotational motion of fluids, i.e., the vortex. Ubiquitously seen in nature and engineering applications, the definition of vortices has been elusive. The Liutex vector provides a unique and systematic description of vortices. The proceedings collects papers presented in the invited workshop "Liutex and Third Generation of Vortex Identification for Engineering Applications" from Aerospace and Aeronautics World Forum 2021. The papers in this book cover both the theoretical aspects of Liutex and many applications in hydrodynamics and aerodynamics. The proceedings is a good reference for researchers in fluid mechanics who are interested in learning about the wide scope of applications of Liutex and using it to develop a new understanding of their research subjects.
Author : Chaoqun Liu
Publisher : Bentham Science Publishers
ISBN 13 : 9811437580
Total Pages : 343 pages
Book Rating : 4.8/5 (114 download)
Download or read book Liutex-based and Other Mathematical, Computational and Experimental Methods for Turbulence Structure written by Chaoqun Liu and published by Bentham Science Publishers. This book was released on 2020-04-28 with total page 343 pages. Available in PDF, EPUB and Kindle. Book excerpt: The knowledge of quantitative turbulence mechanics relies heavily upon the definition of the concept of a vortex in mathematical terms. This reference work introduces the reader to Liutex, which is an accepted, accurate and mathematical definition of a vortex. The core of this book is a compilation of several papers on the subject. presented in the 13th World Congress of Computational Mechanics (WCCM2018), Symposium 704, Mathematics and Computations for Multiscale Structures of Turbulent and Other Complex Flows, New York, United States on July 27, 2018. This compilation also includes other research papers which explain the work done on the vortex definition, vortex identification and turbulence structure from different insight angles including mathematics, computational physics and experiments. The thirteen chapters in this volume will be informative to scientists and engineers who are interested in advanced theories about fluid dynamics, vortex science and turbulence research.
Author : Chaoqun Liu
Publisher : BoD – Books on Demand
ISBN 13 : 1837686408
Total Pages : 126 pages
Book Rating : 4.8/5 (376 download)
Download or read book Vortex Simulation and Identification written by Chaoqun Liu and published by BoD – Books on Demand. This book was released on 2024-01-24 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book includes six chapters covering new vortex theories, vortex identification methods, and vortex simulation and applications. Vortices are ubiquitous in the universe and include tornados, hurricanes, airplane tip vortices, polar vortices, and even star vortices in the galaxy. Vortices are also building blocks, muscles, and sinews of turbulent flows. This book is useful for researchers in hydrodynamics, aerodynamics, thermodynamics, oceanography, meteorology, metallurgy, civil engineering, astronomy, biology, and more. It is also useful for research on the generation, sustenance, modeling, and controlling of turbulence.
Author :
Publisher :
ISBN 13 :
Total Pages : 14 pages
Book Rating : 4.:/5 (683 download)
Download or read book Hairpin Vortex Formation, a Case Study for Unsteady Visualization written by and published by . This book was released on 1999 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: To better understand the vortex dynamics of coherent structures in turbulent and transitional boundary layers, we consider direct numerical simulation of the interaction between a flat-plateboundary-layer flow and an isolated hemispherical roughness element. Of principal interest is the evolution of hairpin vortices that form an interlacing pattern in the wake of the hemisphere, lift away from the wall, and are stretched by the shearing action of the boundary layer. Using animations of unsteady three-dimensional representations of this flow, produced by the vtk toolkit and enhanced to operate in a CAVE virtual environment, we identify and study several key features in the evolution of this complex vortex topology not previously observed in other visualization formats.
Author : T.-L. Hon
Publisher :
ISBN 13 :
Total Pages : 26 pages
Book Rating : 4.:/5 (317 download)
Download or read book Evolution of Hairpin Vortices in a Shear Flow written by T.-L. Hon and published by . This book was released on 1988 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781722215651
Total Pages : 24 pages
Book Rating : 4.2/5 (156 download)
Download or read book Evolution of Hairpin Vortices in a Shear Flow written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-03 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent experimental studies suggest that the hairpin vortex plays an important (and perhaps dominant) role in the dynamics of turbulent flows near walls. In this study a numerical procedure is developed to allow the accurate computation of the trajectory of a 3-D vortex having a small core radius. For hairpin vortices which are convected in a shear flow above a wall, the calculated results show that a 2-D vortex containing a small 3-D disturbance distorts into a complex shape with subsidiary hairpin vortices forming outboard of the original hairpin vortex. As the vortex moves above the wall, it induces unsteady motion in the viscous flow near the wall: numerical solutions suggest that the boundary-layer flow near the wall will ultimately erupt in response to the motion of the hairpin vortex and in the process a secondary hairpin vortex will be created. The computer results agree with recent experimental investigations. Hon, T.-L. and Walker, J. D. A. Glenn Research Center NASA ORDER C-99066-G; RTOP 505-62-21...
Author : D. B. Goldstein
Publisher :
ISBN 13 :
Total Pages : 8 pages
Book Rating : 4.:/5 (742 download)
Download or read book Hairpin Vortex Formation in Poiseuille Flow Due to Two-Hole Suction written by D. B. Goldstein and published by . This book was released on 2001 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: A virtual-surface DNS is used to examine hairpin formation caused by a pair of suction holes below a laminar wall-bounded flow. The work models an experiment, presently underway, in which quasi-periodic hairpins are to be generated in a laminar plane-Poiseuille flow. We present some brief preliminary studies of vortex dynamics and find both symmetric and antisymmetric modes of shedding. We also examine the effect of inter-hole spacing on hairpin formation.
Author : Jiyuan Tu
Publisher : Butterworth-Heinemann
ISBN 13 : 0080982433
Total Pages : 458 pages
Book Rating : 4.0/5 (89 download)
Download or read book Computational Fluid Dynamics written by Jiyuan Tu and published by Butterworth-Heinemann. This book was released on 2012-11-07 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: An introduction to CFD fundamentals and using commercial CFD software to solve engineering problems, designed for the wide variety of engineering students new to CFD, and for practicing engineers learning CFD for the first time. Combining an appropriate level of mathematical background, worked examples, computer screen shots, and step by step processes, this book walks the reader through modeling and computing, as well as interpreting CFD results. The first book in the field aimed at CFD users rather than developers. New to this edition: A more comprehensive coverage of CFD techniques including discretisation via finite element and spectral element as well as finite difference and finite volume methods and multigrid method. Coverage of different approaches to CFD grid generation in order to closely match how CFD meshing is being used in industry. Additional coverage of high-pressure fluid dynamics and meshless approach to provide a broader overview of the application areas where CFD can be used. 20% new content .
Author : Thon-Lon Hon
Publisher :
ISBN 13 :
Total Pages : 223 pages
Book Rating : 4.:/5 (227 download)
Download or read book An Analysis of the Motion and Effects of Hairpin Vortices written by Thon-Lon Hon and published by . This book was released on 1987 with total page 223 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent studies suggest that the hairpin vortex plays an important, possibly dominant, role in the dynamics of turbulent flows near walls. This study addresses the following topics of the motion of hairpin vortices near solid walls on a theoretical basis: the nature of the evolution of hairpin vortices in a shear flow; the type of flow induced near a wall by a convected hairpin vortex; the character of the viscous response near a wall to the hairpin vortex motion; and the nature of the interaction of 2 hairpin vortices. A numerical procedure is developed to allow accurate evaluation of the trajectory of a 3-dimensional vortex for vortices having small cores. The integration method is based on a numerical approximation to the Biot-Savart integral; most existing vortex calculation methods have severe stability problems for vortices with small cores. These problems are overcome with the present method and technique is applied to compute the evolution of convected vortex loops and hairpin vortices, both in uniform flow and in shear flow above a wall. For hairpin vortices evolving in a shear flow, a regenerative process is observed wherein secondary hairpin vortices form outboard of the original hairpin vortex in a manner consistent with experimental observations. Calculations for 2 hairpin vortices, initially close to one another in a shear flow, show that the vortices interact to reinforce one another. Simulations carried out to compute the evolution of hydrogen bubble lines as a hairpin vortex passes show that such vortices can give rise to wall layer streaks.
Author : Jigen Zhou
Publisher :
ISBN 13 :
Total Pages : 440 pages
Book Rating : 4.:/5 (39 download)
Download or read book Self-sustaining Formation of Packets of Hairpin Vortices in a Turbulent Wall Layer written by Jigen Zhou and published by . This book was released on 1997 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Ronald Lee Panton
Publisher : Computational Mechanics
ISBN 13 :
Total Pages : 448 pages
Book Rating : 4.3/5 (91 download)
Download or read book Self-sustaining Mechanisms of Wall Turbulence written by Ronald Lee Panton and published by Computational Mechanics. This book was released on 1997 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: Why is wall turbulence self-sustaining? In this book well-regarded researchers not only discuss what they know and believe, but also speculate on ideas that still require numerical or experimental testing and verification. An initial brief history of boundary layer structure research is followed by chapters on experimental information and specific topics within the subject. There are then sections on computational aspects.
Author : Ahmad Haji-Haidari
Publisher :
ISBN 13 :
Total Pages : 528 pages
Book Rating : 4.:/5 (227 download)
Download or read book Generation and Growth of Single Hairpin Vortices written by Ahmad Haji-Haidari and published by . This book was released on 1990 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Herman Albert Zondag
Publisher :
ISBN 13 : 9789038605173
Total Pages : 178 pages
Book Rating : 4.6/5 (51 download)
Download or read book The Dynamics of Hairpin Vortices in a Laminar Boundary Layer written by Herman Albert Zondag and published by . This book was released on 1997 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
