A Flow Visualization Investigation of the Turbulent Boundary Layer Over Regularly Rough Surfaces
Author | : Sunil Chithranjan.* Tantirige |
Publisher | : |
Total Pages | : 412 |
Release | : 1989 |
Genre | : |
ISBN | : |
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Author | : Sunil Chithranjan.* Tantirige |
Publisher | : |
Total Pages | : 412 |
Release | : 1989 |
Genre | : |
ISBN | : |
Author | : P. A. Aswatha Narayana |
Publisher | : |
Total Pages | : 164 |
Release | : 1977 |
Genre | : Turbulent boundary layer |
ISBN | : |
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.
Author | : Ronald M. C. So |
Publisher | : |
Total Pages | : 276 |
Release | : 1972 |
Genre | : Turbulent boundary layer |
ISBN | : |
Author | : D. E. Abbott |
Publisher | : |
Total Pages | : 17 |
Release | : 1980 |
Genre | : |
ISBN | : |
This project combines both experimental video flow visualization studies and theoretical investigations of a series of phenomenological and theoretical models based upon the three-dimensional details of convected, coherent structural elements of a turbulent flow as it interacts with a solid surface. The progress over the past year has led to the experimental consideration of range of sub-problems including high Reynolds Number (4,000,000) turbulent flows, the effect of surface modification on low-speed streak formation, and the effect of vortex loop interaction with a solid boundary. To augment the visualization pictures, a computerized video-digitizing system has been developed. Preliminary results show tremendous promise for obtaining quantitative data from flow visualization pictures. The specific thrust of the theoretical studies has been focussed on three areas: (1) how two- and three-dimensional vortex structures interact with wall boundary layers, (2) the development of a new type of prediction method for two-dimensional turbulent boundary-layer flows, and (3) improvement in numerical techniques for solving parabolic, boundary-layer equations. (Author).
Author | : |
Publisher | : |
Total Pages | : 302 |
Release | : 2015 |
Genre | : |
ISBN | : |
At sufficiently high Reynolds number, all surfaces are rough, and roughness affects most flows in engineering and the natural sciences. Examples range from atmospheric boundary layers over buildings and canopies, to engineering surfaces with erosion, deposits, etc. To study the roughness effects, we take a high-resolution approach to capture the flow around individual roughness elements using direct and large-eddy simulations (DNS and LES); the goal is to elucidate phenomena which have been difficult to access using physical experiments, and to help develop engineering correlations and models. First, most experiments and turbulence models are based on a standardized type of roughness, sand-grain roughness, which can be described using a single length scale. The relationship between the geometry of an arbitrary surface and the canonical one must be known, to predict critical flow parameters such as the drag, using either experimental correlations or turbulence models. Using numerical experiments, we relate this length-scale to the roughness geometry, and propose a guideline for its prediction in the industrial setting. Next, to explain the dependence of drag on the topographical details, we examine the role of the wake of the roughness elements in the drag generation of a rough surface. The wake field is found to promote vertical momentum transfer and near-wall instability; it might provide a link between geometry details and the engineering modeling of roughness effects. Lastly, we focus on a more realistic flow scenario -- the one with freestream accelerations -- and study the combined effects of roughness and acceleration, a phenomenon widely present in engineering flows over airfoils or complex landscapes. It is first shown, by comparing equilibrium accelerating flows obtained in the present study with the non-equilibrium flows in the literature, that the roughness and acceleration effects are interdependent and depend on the flow equilibrity. Then, using DNS data of a spatially developing flat-plate boundary layer, it is found that the effect coupling develops as the roughness affects the turbulence time scale and thus the flow susceptibility of the acceleration stabilization, while acceleration changes the wake velocity and ultimately the roughness destabilization level.
Author | : Peter William Runstadler (Jr.) |
Publisher | : |
Total Pages | : 342 |
Release | : 1963 |
Genre | : Boundary layer |
ISBN | : |