Stability and Transition in Shear Flows

Stability and Transition in Shear Flows
Author: Peter J. Schmid
Publisher: Springer Science & Business Media
Total Pages: 561
Release: 2012-12-06
Genre: Science
ISBN: 1461301858

A detailed look at some of the more modern issues of hydrodynamic stability, including transient growth, eigenvalue spectra, secondary instability. It presents analytical results and numerical simulations, linear and selected nonlinear stability methods. By including classical results as well as recent developments in the field of hydrodynamic stability and transition, the book can be used as a textbook for an introductory, graduate-level course in stability theory or for a special-topics fluids course. It is equally of value as a reference for researchers in the field of hydrodynamic stability theory or with an interest in recent developments in fluid dynamics. Stability theory has seen a rapid development over the past decade, this book includes such new developments as direct numerical simulations of transition to turbulence and linear analysis based on the initial-value problem.

The Stability of a Viscous Heterogeneous Shear Flow

The Stability of a Viscous Heterogeneous Shear Flow
Author: Frank D. Hains
Publisher:
Total Pages: 37
Release: 1968
Genre:
ISBN:

A numerical method is used to compute the stability of a shear layer embedded between two homogeneous fluid regions of different densities that are moving at uniform but different velocities. The mean flow is specified by a hyperbolic tangent velocity profile and an exponential of a hyperbolic tangent density profile. Numerical results are presented that show the changes in the stability of the layer with the Reynolds number, Froude number, wavenumber of the disturbance, and the gradients of shear and density. Two modes of instability are found: one propagates upstream relative to the moving fluid, the other propagates downstream at a velocity that is always less than the average of the two outer regions. Viscosity tends to stabilize waves that are already stable and to destabilize waves that are unstable. The neutral stability curves appear to have only one branch; therefore, no critical Reynolds numbers were found. Gravity tends to stabilize one mode and to destabilize the other; but when gravity forces are very large, both modes are stabilized. One mode was unstable when the minimum Richardson number across the shear layer exceeded 1/4; therefore, the critical Richardson number for a viscous fluid must be larger than that for an inviscid fluid. (Author).

Physics of Transitional Shear Flows

Physics of Transitional Shear Flows
Author: Andrey V. Boiko
Publisher: Springer Science & Business Media
Total Pages: 286
Release: 2011-09-15
Genre: Science
ISBN: 9400724985

Starting from fundamentals of classical stability theory, an overview is given of the transition phenomena in subsonic, wall-bounded shear flows. At first, the consideration focuses on elementary small-amplitude velocity perturbations of laminar shear layers, i.e. instability waves, in the simplest canonical configurations of a plane channel flow and a flat-plate boundary layer. Then the linear stability problem is expanded to include the effects of pressure gradients, flow curvature, boundary-layer separation, wall compliance, etc. related to applications. Beyond the amplification of instability waves is the non-modal growth of local stationary and non-stationary shear flow perturbations which are discussed as well. The volume continues with the key aspect of the transition process, that is, receptivity of convectively unstable shear layers to external perturbations, summarizing main paths of the excitation of laminar flow disturbances. The remainder of the book addresses the instability phenomena found at late stages of transition. These include secondary instabilities and nonlinear features of boundary-layer perturbations that lead to the final breakdown to turbulence. Thus, the reader is provided with a step-by-step approach that covers the milestones and recent advances in the laminar-turbulent transition. Special aspects of instability and transition are discussed through the book and are intended for research scientists, while the main target of the book is the student in the fundamentals of fluid mechanics. Computational guides, recommended exercises, and PowerPoint multimedia notes based on results of real scientific experiments supplement the monograph. These are especially helpful for the neophyte to obtain a solid foundation in hydrodynamic stability. To access the supplementary material go to extras.springer.com and type in the ISBN for this volume.

Global Stability Analysis of Shear Flows

Global Stability Analysis of Shear Flows
Author: Rameshkumar Bhoraniya
Publisher: Springer Nature
Total Pages: 232
Release: 2023-03-10
Genre: Science
ISBN: 9811995745

This book presents the fundamentals and advanced research on the global stability analysis of the shear flows. The contents investigate the results of global stability analysis for different configurations of internal and external shear flows. The topics covered are global stability analysis of converging-diverging channel flows, axisymmetric boundary layer developed on a circular cylinder, cone and inclined flat-plate boundary layer, and wall jets. It further explains the effect of divergence, convergence, transverse curvature, and pressure gradients on the global stability of the different configurations of shear flows. The book is a valuable reference for beginners, researchers, and professionals working in the field of aerodynamics and marine hydrodynamics.

On the Stability of a Stratified Shear Layer

On the Stability of a Stratified Shear Layer
Author: P. Satyanarayana
Publisher:
Total Pages: 20
Release: 1986
Genre:
ISBN:

The stability of a stratified shear layer is investigated using an exponential density profile and a laminar shear flow with a continuous velocity distribution. It is shown that an exact stability boundary can be obtained from an inhomogeneous inviscid fluid under the action of gravity without the need to impose the Boussinesq approximation. The stability boundary is given by J = k-sq(1 - beta-sq-k-sq) where B is the ratio of the velocity and density gradient scale sizes, J is the Richardson number and k is the perpendicular wavenumber normalized to the velocity gradient scale size; this reduces to the stability boundary derived by Drazin in the limit beta = O. The solution allows for c = beta/2 where c is the normalized phase velocity.