Experimental Study of Turbulence Production Mechanisms in Boundary Layer Flows

Experimental Study of Turbulence Production Mechanisms in Boundary Layer Flows
Author: R. E. Falco
Publisher:
Total Pages: 76
Release: 1985
Genre:
ISBN:

Studies of turbulence structure near a wall show that the production process has many manifestations. Detailed experiments, involving visual information in two mutually orthogonal planes, and simultaneous multiple hot-wire anemometry, along with both experimental and numerical simulations were performed in an attempt to determine the underlying conceptual framework. Results indicate that the wide variety of evolutions observed during the turbulence production process near a wall are all manifestations of the evolution of vortex ring-like eddies with the wall and the wall layer. Additional important evolutions result from the interaction of two of these vortex ring/wall interactions occurring with small spatial and temporal differences. Boundary layer interactions have been divided into (4) classes ranging from weak interactions to ones producing strong turbulence. These classes were simulated experimentally vortex ring/moving wall interactions, and--within the constraints of two-dimensions--qualitatively by simple numerical vortex-in-cell simulations. The instantaneous local thickness of the viscous sublayer and the flow field of the large scale motions play dominant roles in determining which class of evolution is observed.

Experimental Investigation of the Turbulence Production Mechanism in Boundary Layers

Experimental Investigation of the Turbulence Production Mechanism in Boundary Layers
Author: R. E. Falco
Publisher:
Total Pages: 41
Release: 1986
Genre:
ISBN:

Over the past year we have discovered the mechanism of production of the long streaks and a mechanism for creation of vortex ring-like typical eddies, and have demonstrated the occurrence of both within a real turbulent boundary layer. These aspects were the missing links needed to complete the conceptual structural model. This model de-emphasizes the importance of hairpin vortices in wall layer transport. However, experimental determination of the relative importance of each of the elements of the model in low Reynolds number layers is far from complete, and we know very little of the Reynolds number dependence or pressure gradient dependence of the model. What we have learned so far suggests several critical parameters that can be manipulated to control the production of turbulence and hence reduce drag. In the proposed research we want to focus on acquiring additional data to support the rational theory that has been formed so as to provide the basis for determining how much leverage we have in our efforts to control boundary layer turbulence.

Boundary Layer Flows

Boundary Layer Flows
Author: Vallampati Ramachandra Prasad
Publisher: BoD – Books on Demand
Total Pages: 236
Release: 2020-01-22
Genre: Mathematics
ISBN: 1839681853

Written by experts in the field, this book, "Boundary Layer Flows - Theory, Applications, and Numerical Methods" provides readers with the opportunity to explore its theoretical and experimental studies and their importance to the nonlinear theory of boundary layer flows, the theory of heat and mass transfer, and the dynamics of fluid. With the theory's importance for a wide variety of applications, applied mathematicians, scientists, and engineers - especially those in fluid dynamics - along with engineers of aeronautics, will undoubtedly welcome this authoritative, up-to-date book.

Recent Results in Laminar-Turbulent Transition

Recent Results in Laminar-Turbulent Transition
Author: Siegfried Wagner
Publisher: Springer Science & Business Media
Total Pages: 334
Release: 2013-06-05
Genre: Technology & Engineering
ISBN: 3540450602

The 24 papers presented at the international concluding colloquium of the German priority programme (DFG-Verbundschwerpunktprogramm) "Transition", held in April 2002 in Stuttgart. The unique and successful programme ran six years, starting April 1996, and was sponsored mainly by the Deutsche Forschungsgemeinschaft, DFG, but also by the Deutsches Zentrum für Luft-und Raumfahrt, DLR, the Physikalisch-Technische Bundesanstalt Braunschweig, PTB, and Airbus Deutschland. The papers summarise the results of the programme and cover transition mechanisms, transition prediction, transition control, natural transition and measurement techniques, transition - turbulence - separation, and visualisation issues. Three invited papers are devoted to mechanisms of turbulence production, to a general framework of stability, receptivity and control, and a forcing model for receptivity analysis. Almost every transition topic arising in subsonic and transonic flow is covered.

Analysis of Turbulent Boundary Layers

Analysis of Turbulent Boundary Layers
Author: Tuncer Cebeci
Publisher: Elsevier
Total Pages: 423
Release: 2012-12-02
Genre: Technology & Engineering
ISBN: 0323151051

Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculating two-dimensional and axisymmetric laminar and turbulent boundary layers. This book will be useful to readers who have advanced knowledge in fluid mechanics, especially to engineers who study the important problems of design.