Drag Reduction for Turbulent Boundary Layer Flows Using an Oscillating Wall PDF Download
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Author:
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Languages : en
Pages : 0
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Book Description
This research program used experimental measurements and computational simulations to study the drag reduction, and the resulting effects on turbulence structure, for a turbulent wall flow subjected to lateral wall oscillations. Major objectives for this study were to establish wall oscillation conditions resulting in maximum drag reduction, and how the turbulence structure was altered so that this drag reduction was attained. Furthermore we were interested in the drag reduction performance over a range of Reynolds numbers, and the onset of the drag reduction at the start of the oscillating wall section, and the decay of drag reduction downstream of the oscillating wall. Our experiments showed the maximum drag reduction for an oscillating wall is 30%. Furthermore, the drag reduction reaches an asymptotic level with increasing wall oscillation velocity, with the maximum level occurring by approximately W sub wp=15. Drag reduction performance was tested for Reynolds numbers of Re theta =500, 950, 1400 and 2400, and the performance was found to be independent of Reynolds number for this range. Experimental and computational studies of the turbulence structure showed the oscillating wall has dramatic effect in practically eliminating the streak structures. Furthermore, the burst and sweep structures were suppressed.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
This research program used experimental measurements and computational simulations to study the drag reduction, and the resulting effects on turbulence structure, for a turbulent wall flow subjected to lateral wall oscillations. Major objectives for this study were to establish wall oscillation conditions resulting in maximum drag reduction, and how the turbulence structure was altered so that this drag reduction was attained. Furthermore we were interested in the drag reduction performance over a range of Reynolds numbers, and the onset of the drag reduction at the start of the oscillating wall section, and the decay of drag reduction downstream of the oscillating wall. Our experiments showed the maximum drag reduction for an oscillating wall is 30%. Furthermore, the drag reduction reaches an asymptotic level with increasing wall oscillation velocity, with the maximum level occurring by approximately W sub wp=15. Drag reduction performance was tested for Reynolds numbers of Re theta =500, 950, 1400 and 2400, and the performance was found to be independent of Reynolds number for this range. Experimental and computational studies of the turbulence structure showed the oscillating wall has dramatic effect in practically eliminating the streak structures. Furthermore, the burst and sweep structures were suppressed.
Author: Steven M. Trujillo
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Dennis M. Bushnell
Publisher: AIAA (American Institute of Aeronautics & Astronautics)
ISBN:
Category : Science
Languages : en
Pages : 544
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Book Description
Timely in two respects: the first is the growing awareness of the need for energy conservation in both transportation and process industries. The second is the recent emergence and application of several viscous drag reduction techniques. Laminar as well as turbulent flows are covered as are active
Author: Alfredo Soldati
Publisher: Springer
ISBN: 370912574X
Category : Technology & Engineering
Languages : en
Pages : 319
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Book Description
Controlling turbulence is an important issue for a number of technological applications. Several methods to modulate turbulence are currently being investigated. This book describes various aspects of turbulence structure and modulation, and explains and discusses the most promising techniques in detail.
Author: Peter North Blossey
Publisher:
ISBN:
Category :
Languages : en
Pages : 284
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Book Description
Author: Baochun Fan
Publisher: John Wiley & Sons
ISBN: 1118718011
Category : Science
Languages : en
Pages : 397
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Book Description
This book introduces the mathematical techniques for turbulence control in a form suitable for inclusion in an engineering degree program at both undergraduate and postgraduate levels whilst also making it useful to researchers and industrial users of the concepts. It uses a mix of theory, computation and experimental results to present and illustrate the methodologies. It is based on the three part structure, wall turbulence, open loop control and feedback control with emphasis on optimal control methodologies. The book also includes an introduction of basic principles and fundamentals followed by a chapter on the structure of wall turbulence with emphasis on coherent structures. Elsewhere there is focus on control methods of wall turbulence by manipulating the boundaries though their motion and by applying control forces throughout the flow volume. The last two chapters will describe the linear and non-linear optimal controls. This integrated approach will help not only researchers interested in the topic but also graduate or advanced undergraduate students in their course work.
Author: Kamal Poddar
Publisher:
ISBN:
Category : Boundary layer control
Languages : en
Pages : 362
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Book Description
Author: Ramakrishna Balasubramanian
Publisher:
ISBN:
Category : Navier-Stokes equations
Languages : en
Pages : 126
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Book Description
Author: Robert L. Ash
Publisher:
ISBN:
Category : Drag (Aerodynamics)
Languages : en
Pages : 52
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Book Description
Author: Zambri Harun
Publisher: BoD – Books on Demand
ISBN: 183769835X
Category : Science
Languages : en
Pages : 146
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Book Description
Fluid mechanics is a branch of physics with important applications in daily life. The calculation of flow drag on automobiles and high-speed trains benefits from theories in fluid mechanics. Moreover, many mechanical-based devices such as fluid pumps contribute to efficiency, and thus, to the modernization of society. This book highlights the experimental and theoretical aspects of wall-bounded flows to provide important information about related theories and applications. Boundary layer flow experimentation, modelling, and simulation must be considered together to obtain accurate calculations of parameters such as velocity profiles, pressure distribution, and turbulence level. This book is organized into three sections on the structure of the boundary layer, drag reduction initiatives using active control, and the verification and applications of flow mechanics. Chapters discuss the boundary layer type of different pressure gradients, Reynolds number, and speeds from 5 m/s to Mach 3. They also present the results of research on the active control technique for drag reduction initiatives to achieve efficient turbulence in high-speed applications, flow meter devices, and turbulence-generated noise mitigation initiatives.
