Management and Control of Unsteady and Turbulent Flows

Management and Control of Unsteady and Turbulent Flows
Author:
Publisher:
Total Pages: 15
Release: 1991
Genre:
ISBN:

Conclusions from a wide range of experiments in transitioning, turbulent, separated and unsteady flow fields include the following highlights: The simultaneous generation of controlled phase-coupled plane TS waves and oblique waves was used to investigate the development of three dimensional disturbances and mechanisms of transition in a Blasius boundary layer. From these experiments, the detuning of the fundamental/subharmonic resonance emerges as a primary candidate for the transition process under natural conditions. Three dimensional mappings of the Reynolds-stress-producing events in turbulent boundary layers over a range of Reynolds numbers and initial conditions have demonstrated that an integral-size of these dynamical motions scales better with outer variables as compared with inner variables. While the wall or inner layer is responsible for their initial, the hierarchy of their scales in the log layer expands with Reynolds number according to this outer scaling. Real-time reactive control of a model unsteady separating flow was successfully implemented using a simple scheme for the detention of the separation.

Control and Management of Unsteady and Turbulent Flows

Control and Management of Unsteady and Turbulent Flows
Author:
Publisher:
Total Pages: 29
Release: 1993
Genre:
ISBN:

Active input of tuned and detuned two-dimensional and oblique modes in a layer was found to lead to the growth of near-subharmonic modes as well as numerous sum and difference modes, thereby emulating 'natural' transition. Acoustic receptivity of laminar boundary layers with nonlocalized low-amplitude periodic waviness was experimentally investigated and compared favorably to theoretical predictions. Closed loop excitation of axisymmetric and azimuthal modes in a free round jet were used to reveal the character of high Reynolds number transition (i.e., supercritical Hopf bifurcation) and to study mode selection and switching. Suction and blowing were shown to be capable of controlling the asymmetric flow about the forebodies of aircraft and missiles and the experiments indicate that the suction bleed coefficient must increase like the 3.9 power of the velocity to balance the effects of geometric instability at the tip. The effects of yaw on such asymmetries were also documented. A strategy to suppress the dynamic-stall vortex over a range of operating parameters, using controlled leading-edge suction to prevent accumulation of reverse-flowing fluid, was successfully developed from a study of the mechanisms responsible for the evolution of the vortex. The National Diagnostic Facility was completed and several collaborative experiments are scheduled during 1994. Turbulence, Separated flows, Unsteady flows, Transition, Forebody flows, Pitching airfoils, Jet flows, Control.

Flow Control

Flow Control
Author: Mohamed Gad-el-Hak
Publisher: Springer Science & Business Media
Total Pages: 533
Release: 2003-07-01
Genre: Science
ISBN: 3540696725

No be certain it can is not based mathematics. knowledge if upon da Vinci, (Leonardo 1452 1519) the humankind. Thinking is one greatest of Joys of Galilei, (Galileo 1564 1642) Now I think is to be the root all hydrodynamics and is at of physical science, second the to none in its mathematics. present beauty of Thomson (William (Lord Kelvin), 1824 1907) The book contains the lecture notes of of the nine instructors at present eight the short Flow Control: Fundamentals and which held course was Practices, in the week 24 28 June and Carg6se, Corsica, France, during 1996, repeated at the of Notre 9 13 1996. University Dame, Indiana, September Following the week in the course a on same was held. Corsica, 5 day workshop topic Selected from the scheduled to 1998 workshop are papers appear early special volume of the International Journal Heat Thermo of Experimental Transfer, and Fluid All Mechanics. three events were Jean Paul dynamics, organized by Bonnet of Universit6 de Andrew Pollard of Univer Poitiers, France, Queen's at and Mohamed Gad el Hak of the of sity Kingston, Canada, University Notre U.S.A.

Control of Flow Instabilities and Unsteady Flows

Control of Flow Instabilities and Unsteady Flows
Author: G.E.A. Meier
Publisher: Springer
Total Pages: 344
Release: 1996
Genre: Science
ISBN:

This volume contributes to one of the most important topics of Fluid Mechanics in future and presents recent research results on control theory and applied control methods. Understanding and handling of control methods of nonlinear systems, typical of Fluid Mechanics, is the key to reduce losses and to improve the efficiency and safety of technical processes.

Transport and Coherent Structures in Wall Turbulence

Transport and Coherent Structures in Wall Turbulence
Author: Sedat Tardu
Publisher: John Wiley & Sons
Total Pages: 500
Release: 2014-10-06
Genre: Technology & Engineering
ISBN: 1848213956

Wall bounded turbulent flows are of major importance in industrial and environmental fluid mechanics. The structure of the wall turbulence is intrinsically related to the coherent structures that play a fundamental role in the transport process. The comprehension of their regeneration mechanism is indispensable for the development of efficient strategies in terms of drag control and near wall turbulence management. This book provides an up-to-date overview on the progress made in this specific area in recent years.

Flow Control

Flow Control
Author: Mohamed Gad-el-Hak
Publisher: Cambridge University Press
Total Pages: 445
Release: 2000-08-15
Genre: Science
ISBN: 0521770068

A thorough treatment of the basics of flow control and flow control practices.

Turbulent Flow and Boundary Layer Theory: Selected Topics and Solved Problems

Turbulent Flow and Boundary Layer Theory: Selected Topics and Solved Problems
Author: Jafar Mehdi Hassan
Publisher: Bentham Science Publishers
Total Pages: 303
Release: 2021-08-11
Genre: Science
ISBN: 1681088126

Turbulent Flow and Boundary Layer Theory: Selected Topics and Solved Problems explains fundamental concepts of turbulent flow with boundary layer analysis. A general introduction to turbulent flow familiarizes the reader with the mechanics of turbulence in fluid flow in both nature and engineering applications. The book also explains related concepts including transient flow, methods for controlling transients, turbulent models and dynamic equations for unsteady flow through closed conduits. The contents of the book are designed to help both students and teachers in carrying out turbulent flow analysis and solving problems in engineering and hydraulic applications. Key Features - all the basic concepts in turbulent flow are clearly identified and presented in a simple manner with illustrative and practical examples. - includes a self-contained approach to the subject, indicating prerequisite materials and information needed from courses. - each chapter also has a set of questions and problems to test the student’s power of comprehending the topics. - provides an exhaustive appendix on interesting examples Turbulent Flow and Boundary Layer Theory: Selected Topics and Solved Problems a useful textbook for students of engineering. It also serves as a quick reference for professionals, researchers and project consultants involved with processes that require turbulent flow and boundary layer methods analysis.

Tackling Turbulent Flows in Engineering

Tackling Turbulent Flows in Engineering
Author: Anupam Dewan
Publisher: Springer Science & Business Media
Total Pages: 129
Release: 2010-10-23
Genre: Technology & Engineering
ISBN: 3642147674

The emphasis of this book is on engineering aspects of fluid turbulence. The book explains for example how to tackle turbulence in industrial applications. It is useful to several disciplines, such as, mechanical, civil, chemical, aerospace engineers and also to professors, researchers, beginners, under graduates and post graduates. The following issues are emphasized in the book: - Modeling and computations of engineering flows: The author discusses in detail the quantities of interest for engineering turbulent flows and how to select an appropriate turbulence model; Also, a treatment of the selection of appropriate boundary conditions for the CFD simulations is given. - Modeling of turbulent convective heat transfer: This is encountered in several practical situations. It basically needs discussion on issues of treatment of walls and turbulent heat fluxes. - Modeling of buoyancy driven flows, for example, smoke issuing from chimney, pollutant discharge into water bodies, etc