Wall Turbulence Control
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Wall Turbulence Control
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Author : Sedat Tardu
language : en
Publisher: John Wiley & Sons
Release Date : 2017-05-01
Wall Turbulence Control written by Sedat Tardu and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-05-01 with Science categories.
Wall turbulence control is a major subject, the investigation of which involves significant industrial, environmental and fundamental consequences. Wall Turbulence Control addresses recent advances achieved in active and passive wall turbulence control over the past two decades. This valuable reference for scientists, researchers and engineers provides an updated view of the research into this topic, including passive control, optimal and suboptimal control methodology, linear control and control using adaptive methods (neural networks), polymer and bubble injection, electromagnetic control and recent advances in control by plasma.
Principles Of Turbulence Control
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Author : Baochun Fan
language : en
Publisher: John Wiley & Sons
Release Date : 2022-05-17
Principles Of Turbulence Control written by Baochun Fan and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-05-17 with Science categories.
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.
Reactive Control Of Turbulent Wall Bounded Flows For Skin Friction Drag Reduction
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Author : Stroh, Alexander
language : en
Publisher: KIT Scientific Publishing
Release Date : 2019-01-04
Reactive Control Of Turbulent Wall Bounded Flows For Skin Friction Drag Reduction written by Stroh, Alexander and has been published by KIT Scientific Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-01-04 with categories.
Transport And Coherent Structures In Wall Turbulence
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Author : Sedat Tardu
language : en
Publisher: John Wiley & Sons
Release Date : 2014-10-06
Transport And Coherent Structures In Wall Turbulence written by Sedat Tardu and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-10-06 with Technology & Engineering categories.
Wall bounded turbulent flows are of major importance in industrial and environmental fluid mechanics. The structure of the wall turbulence is intrinsically related to the coherent structures that play a fundamental role in the transport process. The comprehension of their regeneration mechanism is indispensable for the development of efficient strategies in terms of drag control and near wall turbulence management. This book provides an up-to-date overview on the progress made in this specific area in recent years.
Transition And Turbulence Control
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Author : Mohamed Gad-el-Hak
language : en
Publisher: World Scientific
Release Date : 2006
Transition And Turbulence Control written by Mohamed Gad-el-Hak and has been published by World Scientific this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Science categories.
This volume contains articles based on lectures given at the Workshop on Transition and Turbulence Control, hosted by the Institute for Mathematical Sciences, National University of Singapore, 8OCo10 December 2004. The lecturers included 13 of the worldOCOs foremost experts in the control of transitioning and turbulent flows. The chapters cover a wide range of subjects in the broad area of flow control, and will be useful to researchers working in this area in academia, government laboratories and industry. The coverage includes control theory, passive, active and reactive methods for controlling transitional and turbulent wall-bounded flows, noise suppression and mixing enhancement of supersonic turbulent jets, compliant coatings, modern flow diagnostic systems, and swept wing instabilities."
Drag Reduction In Near Wall Turbulent Flow
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Author : Peter North Blossey
language : en
Publisher:
Release Date : 1999
Drag Reduction In Near Wall Turbulent Flow written by Peter North Blossey and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with categories.
Near Wall Turbulence And Utilisation Of The Nonlinear Dynamics Towards Control Of Turbulent Flows
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Author : Anubhav Kushwaha
language : en
Publisher:
Release Date : 2017
Near Wall Turbulence And Utilisation Of The Nonlinear Dynamics Towards Control Of Turbulent Flows written by Anubhav Kushwaha and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Direct numerical simulations of plane Poiseuille flow are performed in an extended domain at transitional Reynolds numbers. In minimal domains, turbulence in this Reynolds number range displays substantial intermittency that is associated with chaotic movement of turbulent trajectories between lower (LB) and upper branch (UB) invariant solutions known as exact coherent states (ECS). We address the relationship between temporal dynamics in minimal channels and spatiotemporal dynamics in extended domains. Both temporal and spatial analyses of the turbulent velocity fields are performed. These analyses partition the flow characteristics into low-, intermediate- and high-drag classes. The temporal and spatial analysis methods, although completely independent of one another, yield very similar results for both low- and high-drag regions. The conditional mean profiles in regions of low-drag closely resemble those found in low-drag temporal intervals in the minimal channel. Finally, we compare turbulence and LB-ECS and show that both the local near-wall structure in the low-drag patches of the large domain and the conditional mean profiles in the near-wall region resemble those of an LB minimal domain ECS. Lower and upper branch ECS from one particular family of solutions are imprinted separately on a turbulent flow in the minimal channel at transitional Reynolds numbers. Specifically, the spatial patterns of their wall shear stress are imprinted on the channel-wall that moves in the wall-normal direction only. The motion of the wall results in a travelling wave of wall deformation in streamwise or spanwise direction. When an LB-ECS is imprinted, drag-reduction is observed for most of the cases, and a maximum drag reduction of just over 15% is achieved. The resultant flow field shows characteristics of a flow with lesser drag and the flow trajectories pass through the vicinity of the imprinted LB-ECS in the state space. When a UB is imprinted on the flow, the drag increases. In such cases, the trajectories remain in the high-drag region of the state space. These results indicate that flow can be driven toward a desired state by manipulating the near-wall dynamics using information from that state. This opens many avenues for the development of new flow control strategies.
Reactive Control Of Turbulent Wall Bounded Flows For Skin Friction Drag Reduction
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Author : Alexander Stroh
language : en
Publisher: Saint Philip Street Press
Release Date : 2020-10-09
Reactive Control Of Turbulent Wall Bounded Flows For Skin Friction Drag Reduction written by Alexander Stroh and has been published by Saint Philip Street Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-10-09 with categories.
The work presents an attempt to improve the understanding of reactive drag reducing control of near-wall turbulence with respect to limitations present in a realistic application scenario. The reference reactive control scheme of opposition control is studied using direct numerical simulation through the consideration of various application oriented restrictions, i.e. local control application, limited spatial and temporal resolution of the scheme, sensor noise and control elements arrangement. This work was published by Saint Philip Street Press pursuant to a Creative Commons license permitting commercial use. All rights not granted by the work's license are retained by the author or authors.
Turbulence Control In Wall Jets
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Author : Jonathan Latim
language : en
Publisher:
Release Date : 2016
Turbulence Control In Wall Jets written by Jonathan Latim and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Boundary layer categories.
The turbulent boundary layer has been the focus of many studies over the last century or so due to its engineering significance. Recent studies have shown that the turbulent boundary layer encapsulates extremely energetic large-scale structures which play a much more significant role in its dynamics than has been previously thought. Further, these large scales amplitude and frequency modulate the finer scales of turbulence. This offers a path to control wall turbulence by controlling the large-scales of the flow. The focus of this thesis is to establish ways to manipulate the energy of the large-scale structures in a model turbulent boundary layer and characterize its effect. The plane wall jet was chosen as the model flow field because it is possible to perturb/excite the large-scales at the onset of turbulence independent of the finer scales of turbulence. Hot-wire anemometry was used to carryout velocity measurements in at plane wall jet at streamwise locations up to three hundred times the jet exit slot height. Three different passive perturbation configurations were used to manipulate the energy of the large-scale structures of the plane wall jet. The different perturbation configurations used were a rod, sandpaper and sandpaper and a still wire. All the perturbations were carried out in the vicinity of the jet exit. The unforced wall jet was used as the baseline to compare the effect of these perturbations. All the perturbation cases were able to alter the energy of the large-scale structures in the flow. However, the large-scale structures were shown to be most energetic and reached closest to the wall in the flow that was perturbed using the rod than in all other flow cases at all streamwise positions considered. Last but not least, tic and reached closest to the wall in the flow that was perturbed using the sandpaper and the sandpaper and string configurations showed less energetic large-scale structures at all streamwise locations than in an unforced wall jet. However, the large-scale structures in the sandpaper and string configuration were more energetic than the large scale structures in the sandpaper configuration at all streamwise locations.
Recent Developments In Turbulence Management
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Author : K.-S. Choi
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Recent Developments In Turbulence Management written by K.-S. Choi and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Technology & Engineering categories.
The European Drag Reduction Meeting has been held on 15th and 16th November 1990 in London. This was the fifth of the annual European meetings on drag reduction in engineering flows. The main objective of this meeting was to discuss up-to-date results of drag reduction research carried out in Europe. The organiser has adopted the philosophy of discussing the yesterday's results rather than the last year's results. No written material has therefore been requested for the meeting. It was only after the meeting the submission of papers was requested to the participants, from which 16 papers were selected for this proceedings volume. The meeting has attracted a record number of participants with a total of 52 researchers from seven European countries, U. K. , France, Germany, the Netherlands, Italy, Switzerland and U. S. S. R. as well as from Japan, Canada and Australia. The subjects covered in this proceedings volume include riblets, LEBUs (Large Eddy Break-Up device), surface roughness, compliant surfaces and polymer additives. Riblets seem to be one of the most extensively studied devices in the past years. Reflecting this situation in the European community, there are six papers on riblets covering their practical applications to aircraft and to a model ship, near-wall coherent structure of the boundary layer and effects of flow three-dimensionality. Possibility of heat-transfer enhancement with riblets and potential use in the laminar flow are also investigated. An analytical model is developed for the boundary-layer with a LEBU device.