Control Of Flow Instabilities And Unsteady Flows

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.

At the 37th Prandtl memorial lecture on Regions of Viccous Flow, H.Oertel 1994 developed for the first time the stability theory of local perturbations in boundary layers and wake flows, as well as their practical application in the flow control of vehicle flows and the boundary layer of civil aircraft wings.This work presents how the stability theory concept of absolute instability has advanced and proven in practice in the last 15 years in terms of the efficient flow control.

A state-of-the art analysis of studies in the field of instability of flows, this book contains chapters by leading experts in fluid mechanics. One of the primary aims of the contributors is to determine fruitful directions for future advanced studies and research.

Computation of Unsteady Internal Flows provides an in-depth understanding of unsteady flow modeling and algorithms. This understanding enables suitable algorithms and approaches for particular fields of application to be selected. In addition, the understanding of the behavior of algorithms gained allows practitioners to use them more safely in existing codes, enabling meaningful results to be produced more economically. Features of Computation of Unsteady Internal Flows: Specialized unsteady flow modeling algorithms, their traits, and practical tips relating to their use are presented. Case studies considering complex, practically significant problems are given. Source code and set-up files are included. Intended to be of a tutorial nature, these enable the reader to reproduce and extend case studies and to further explore algorithm performances. Mathematical derivations are used in a fashion that illuminates understanding of the physical implications of different numerical schemes. Physically intuitive mathematical concepts are used. New material on adaptive time stepping is included. £/LIST£ Audience: Researchers in both the academic and industrial areas who wish to gain in-depth knowledge of unsteady flow modeling will find Computation of Unsteady Internal Flows invaluable. It can also be used as a text in courses centered on computational fluid dynamics.

This single-volume work gives an introduction to the fields of transition, turbulence, and combustion modeling of compressible flows and provides the physical background for today’s modeling approaches in these fields. It presents basic equations and discusses fundamental aspects of hydrodynamical instability.

This book contains the outcome of the international meeting on instability, control and noise generated by massive flow separation that was organized at the Monash Center, in Prato, Italy, September 4-6, 2013. The meeting served as the final review of the EU-FP7 Instability and Control of Massively Separated Flows Marie Curie travel grant and was supported by the European Office of Aerospace Research and Development. Fifty leading specialists from twelve countries reviewed the progress made since the 50s of the last century and discussed modern analysis techniques, advanced experimental flow diagnostics and recent developments in active flow control techniques from the incompressible to the hypersonic regime. Applications involving massive flow separation and associated instability and noise generation mechanisms of interest to the aeronautical, naval and automotive industries have been addressed from a theoretical, numerical or experimental point of view, making this book a unique source containing the state-of-the-art in separated flow instability and its control.

This book presents the new discovery of the origin of turbulence from Navier–Stokes equations. The fully developed turbulence is found to be composed of singularities of flow field. The mechanisms of flow stability and turbulent transition are described using the energy gradient theory, which states all the flow instability and breakdown resulted from the gradient of the total mechanical energy normal to the flow direction. This approach is universal for flow instability in Newtonian flow and non-Newtonian flow. The theory has been used to solve several problems, such as plane and pipe Poiseuille flows, plane Couette flow, Taylor–Couette flow, flows in straight coaxial annulus, flows in curved pipes and ducts, thermal convection flow, viscoelastic flow, and magnet fluid flow, etc. The theory is in agreement with results from numerical simulations and experiments. The analytical method used in this book is novel and is different from the traditional approaches. This book includes the fundamental basics of flow stability and turbulent transition, the essentials of the energy gradient theory, and the applications of the theory to several practical problems. This book is suitable for researchers and graduate students.