1R39. Origin of Turbulence in Near-Wall Flows. - AV Boiko, GR Grek, AV Dovgal, VV Kozlov (Inst of Theor and Appl Mech, Siberian Branch, Russian Acad of Sci, Novosibirsk, 630090, Russia). Springer-Verlag, Berlin. 2002. 267 pp. ISBN 3-540-42181-5. $89.95.
Reviewed by DR Dowling (Dept of Mech Eng, Univ of Michigan, 2019 W.E. Lay Automotive Lab, Ann Arbor MI 48109-2121).
In seven chapters, this focused monograph offers a wide-ranging review of theoretical, numerical, and experimental investigations of incompressible near-wall flows in the parametric region that lies between fully-laminar and fully-turbulent conditions. Although the text and figures fill only 217 pages, the topic coverage is excellent while the bibliography spanning 45 pages supplies the interested reader with abundant opportunity to locate additional material on the topics covered. The book is clearly intended for a sophisticated audience having considerable prior exposure to flow stability. The coverage of some topics—the mathematical ones in particular—might be impenetrable to those with only cursory prior knowledge of these subjects.
The first chapter is a highly condensed review of linear stability theory of parallel flows. It provides definitions of various critical parameters and adequately covers the concepts of convective and absolute instability, and the differences in spatial and temporal development of instabilities. The classical field equations (Orr-Sommerfeld and Rayleigh) are derived, and the form of their solutions is discussed. This chapter also covers the lift-up effect, the flow-perturbation equivalent of Reynolds shear stress.
The second chapter is a survey of near-wall, nearly parallel stability results. A full presentation of Blasius boundary layer stability is provided including comparisons between experiments and theory. Non-parallel flow effects and experimental difficulties are discussed. Results from plane Poiseuille and 3D (swept wing) boundary layers are included, too.
The third chapter covers the receptivity of boundary layers to free-stream disturbances. Here, the requisite matching of both the spatial scale and the frequency of external disturbances to potential instability waves is discussed. Both localized spatial (eg surface roughness) and extended temporal (eg acoustic wave) excitations are considered as are both 2D and 3D boundary layers.
The fourth chapter presents the phenomenology of the later stages of boundary layer transition after the main instability waves have arisen. The K and N regimes of Tollmien-Schlichting (T-S) wave breakdown into lambda-vortices are discussed along with quantitative wave amplitude predictions from the Ginzburg-Landau equation and for secondary-flow Floquet-type instabilities. This chapter closes with a discussion of the characteristics of turbulent spots and instabilities in streamwise and cross-flow vortices.
The fifth chapter covers laminar to turbulent transition when the free-stream turbulence level is greater than 1%. Attention is focused primarily on the formation and characteristics of streamwise streaks that form in a Blasius boundary layer at high free-stream turbulence levels. The origin of these streaks is tied to free-stream vortical structures. The text discusses investigations of such streaks and structures when spawned by unsteady blowing and small airfoils located just upstream of the leading edge of a flat plate. The second half of the chapter discusses transition mechanisms including T-S wave growth and the interaction of streaks and turbulent spots.
The sixth chapter discusses transition to turbulence in separation bubbles and initially presents results for 2D disturbance waveforms, growth rates, and phase velocities. The discussion is extended to include axisymmetric separation bubbles where the additional curvature tends to make separated flows more stable, and also to stability and separation in 3D boundary layers where 2D and cross-flow instabilities may interact. The final sections of the chapter address excitation of separation bubbles, the effects of increased forcing levels, the upstream influence of fluctuations occuring near-flow reattachment, the formation of coherent vortices, and the potential for instability and separation control.
The final chapter presents an overview of transition prediction and control. Naturally, the e-to-n method is covered first and is followed by individual discussions of potential active-surface (suction and blowing, heating and cooling, vibration) and passive-surface (body shaping, riblets) transition control techniques.
Overall, the monograph provides a thorough yet compact review of wall-bounded flow stability drawn from the extensive modern literature in both Russian and English language publications. Unfortunately, it is somewhat marred by poor original figures and terse figure captions. In addition, many important mathematical details are often not specified, and the text jumps back and forth between dimensionless and dimensional presentations of equations and results. The written English is understandable, and its deviations from standard usage are usually benign. However, on rare occasions, typographical errors confuse the intended discussion, such as in the material on adjoint operators and their use in receptivity calculations.
Because of its compact content, this reviewer recommends Origin of Turbulence in Near-Wall Flows for technical libraries. It should also be considered by specialists in shear flow and boundary layer stability.
