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The Effects Of Near Wall Control On The Structure And Dynamics Of Wall Bounded Turbulent Flows
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Book Synopsis The Effects of Near-Wall Control on the Structure and Dynamics of Wall-Bounded Turbulent Flows by :
Download or read book The Effects of Near-Wall Control on the Structure and Dynamics of Wall-Bounded Turbulent Flows written by and published by . This book was released on 2005 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Improved understanding of unsteady flow physics has led to a wealth of flow control applications in which fluid perturbations are deliberately introduced into a large-scale flow with the goal of affecting its global characteristics. Research into these methods has included separation control, enhanced mixing, and reduction of turbulent skin friction. Interest in turbulence control has grown due to numerical computations at low Reynolds number flow [3, 4, 5] which indicate that the turbulence and drag can be reduced by a variety of fluidic actuations. The difficulty with these methods is that even though computationally they provide promising results, implementing them in a physical experiment proves very difficult. Other actuation methods that have been studied experimentally include localized heating [6], piezo-electric flaps [7], oscillatory blowing [8], synthetic jets [9], surface motion [10] and plasma discharge [11].
Book Synopsis Modeling and Simulation of Wall-bounded Turbulent Flows with Pressure-gradient and Compressibility Effects by : Kevin Patrick Griffin
Download or read book Modeling and Simulation of Wall-bounded Turbulent Flows with Pressure-gradient and Compressibility Effects written by Kevin Patrick Griffin and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent wall-bounded flows are ubiquitous in engineering and understanding and predicting their dynamics is necessary to address pressing grand challenges in aerospace, energy, and environmental science. For example, control and prediction of wall-bounded turbulence can lead to improved aerodynamic performance of air, land, and sea vehicles, increased efficiency of gas turbines used for electricity generation or propulsion, and accurate predictions of changes in the weather or climate. However, for most real applications, directly simulating the governing physics is intractably expensive even when the world's largest supercomputers are employed. The immense computational complexity of simulating turbulence is due to its multiscale nature; quantities of engineering interest, such as aerodynamic forces on a vehicle, manifest on the macroscale but they depend strongly on accurately predicting microscale phenomena such as turbulent kinetic energy dissipation. To address the high cost of direct simulations of turbulence, it is common to use physical modeling, which is the process of simplifying the governing equations and boundary conditions in order to obtain approximate variants that are computationally efficient to simulate. If the models are accurate, then the resulting solutions can be useful to make engineering design decisions at affordable cost. Specifically, this work focuses on the modeling of turbulent flows near solid boundaries since this is often the rate-limiting region which dominates the computational cost of a simulation. The direct impact of the models developed herein will be that advanced models can deliver accurate engineering predictions at reduced computational costs. To quantify this impact, we present detailed estimates of the grid-point and time-step requirements for simulations of incompressible and compressible wall-bounded flows. When paired with estimates for the growth of computational power over time, these estimates are useful for planning the types of simulations that will be tractable in the future. For the wall models developed in this work, it is assumed that the boundary-layer thickness can be computed reliably. However in complex flows, this is not trivial to define because of the inherent complexity of the background inviscid flow. In this work, a robust method for computing the boundary layer thickness is developed. The proposed method is based on estimating the inviscid base flow that leads to the actual observed viscous solution. Then, the wall-normal location of the departure of the viscous solution from the reconstructed inviscid one is labeled as the boundary layer thickness. This method is used throughout this work. Two models for the near-wall flow are presented for incompressible flows. The first model is for flows over complex geometries with strong streamwise pressure gradients. Lagrangian history effects are incorporating by introducing additional dependence of the wall model on the outer partial differential equation solver. The second model is designed for cases where computational resources are extremely limited and even the boundary layer is difficult to resolve (e.g., very high Reynolds number flows). The boundary layer wake is incorporated into the wall model to expand its domain of applicability. Both of these models are found to improve the prediction of the wall shear stress in a priori analysis. In applications with significant wall heat transfer, such as high-speed aerospace applications, wall-normal variations in density and viscosity can alter the structure of wall-bounded turbulent flows. In this work, a compressible velocity transformation is developed, which enables the mapping of a wide range of compressible velocity profiles to a single universal incompressible law of the wall. The proposed transformation is unique in that it is successful in collapsing data from channel and pipe flows and boundary layers with and without heat transfer. In addition, the inverse of this transformation is derived and applied as a wall model for large-eddy simulation. It is found that the model is significantly more accurate than the classical model, especially in applications with strong wall heat transfer.
Book Synopsis Flow Control by : Mohamed Gad-el-Hak
Download or read book Flow Control written by Mohamed Gad-el-Hak and published by Springer Science & Business Media. This book was released on 2003-07-01 with total page 533 pages. Available in PDF, EPUB and Kindle. Book excerpt: No be certain it can is not based mathematics. knowledge if upon da Vinci, (Leonardo 1452 1519) the humankind. Thinking is one greatest of Joys of Galilei, (Galileo 1564 1642) Now I think is to be the root all hydrodynamics and is at of physical science, second the to none in its mathematics. present beauty of Thomson (William (Lord Kelvin), 1824 1907) The book contains the lecture notes of of the nine instructors at present eight the short Flow Control: Fundamentals and which held course was Practices, in the week 24 28 June and Carg6se, Corsica, France, during 1996, repeated at the of Notre 9 13 1996. University Dame, Indiana, September Following the week in the course a on same was held. Corsica, 5 day workshop topic Selected from the scheduled to 1998 workshop are papers appear early special volume of the International Journal Heat Thermo of Experimental Transfer, and Fluid All Mechanics. three events were Jean Paul dynamics, organized by Bonnet of Universit6 de Andrew Pollard of Univer Poitiers, France, Queen's at and Mohamed Gad el Hak of the of sity Kingston, Canada, University Notre U.S.A.
Book Synopsis On the Structure of Wall-bounded Turbulent Flows by :
Download or read book On the Structure of Wall-bounded Turbulent Flows written by and published by . This book was released on 1983 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Near-wall Turbulence and Utilisation of the Nonlinear Dynamics Towards Control of Turbulent Flows by : Anubhav Kushwaha
Download or read book Near-wall Turbulence and Utilisation of the Nonlinear Dynamics Towards Control of Turbulent Flows written by Anubhav Kushwaha and published by . This book was released on 2017 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1988 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA Technical Memorandum written by and published by . This book was released on 1994 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Handbook of Fluid Dynamics by : Richard W. Johnson
Download or read book Handbook of Fluid Dynamics written by Richard W. Johnson and published by CRC Press. This book was released on 2016-04-06 with total page 1544 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Fluid Dynamics offers balanced coverage of the three traditional areas of fluid dynamics—theoretical, computational, and experimental—complete with valuable appendices presenting the mathematics of fluid dynamics, tables of dimensionless numbers, and tables of the properties of gases and vapors. Each chapter introduces a different fluid dynamics topic, discusses the pertinent issues, outlines proven techniques for addressing those issues, and supplies useful references for further research. Covering all major aspects of classical and modern fluid dynamics, this fully updated Second Edition: Reflects the latest fluid dynamics research and engineering applications Includes new sections on emerging fields, most notably micro- and nanofluidics Surveys the range of numerical and computational methods used in fluid dynamics analysis and design Expands the scope of a number of contemporary topics by incorporating new experimental methods, more numerical approaches, and additional areas for the application of fluid dynamics Handbook of Fluid Dynamics, Second Edition provides an indispensable resource for professionals entering the field of fluid dynamics. The book also enables experts specialized in areas outside fluid dynamics to become familiar with the field.
Book Synopsis Engineering Fluid Dynamics 2019-2020 by : Bjørn H. Hjertager
Download or read book Engineering Fluid Dynamics 2019-2020 written by Bjørn H. Hjertager and published by MDPI. This book was released on 2021-02-25 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the successful submissions to a Special Issue of Energies entitled “Engineering Fluid Dynamics 2019–2020”. The topic of engineering fluid dynamics includes both experimental and computational studies. Of special interest were submissions from the fields of mechanical, chemical, marine, safety, and energy engineering. We welcomed original research articles and review articles. After one-and-a-half years, 59 papers were submitted and 31 were accepted for publication. The average processing time was about 41 days. The authors had the following geographical distribution: China (15); Korea (7); Japan (3); Norway (2); Sweden (2); Vietnam (2); Australia (1); Denmark (1); Germany (1); Mexico (1); Poland (1); Saudi Arabia (1); USA (1); Serbia (1). Papers covered a wide range of topics including analysis of free-surface waves, bridge girders, gear boxes, hills, radiation heat transfer, spillways, turbulent flames, pipe flow, open channels, jets, combustion chambers, welding, sprinkler, slug flow, turbines, thermoelectric power generation, airfoils, bed formation, fires in tunnels, shell-and-tube heat exchangers, and pumps.
Book Synopsis Thermofluid Dynamics of Turbulent Flows by : Michele Ciofalo
Download or read book Thermofluid Dynamics of Turbulent Flows written by Michele Ciofalo and published by Springer Nature. This book was released on 2021-08-16 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides the theoretical fundamentals on turbulence and a complete overview of turbulence models, from the simplest to the most advanced ones including Direct and Large Eddy Simulation. It mainly focuses on problems of modeling and computation, and provides information regarding the theory of dynamical systems and their bifurcations. It also examines turbulence aspects which are not treated in most existing books on this subject, such as turbulence in free and mixed convection, transient turbulence and transition to turbulence. The book adopts the tensor notation, which is the most appropriate to deal with intrinsically tensor quantities such as stresses and strain rates, and for those who are not familiar with it an Appendix on tensor algebra and tensor notation are provided.
Book Synopsis Statistical Approach to Wall Turbulence by : Sedat Tardu
Download or read book Statistical Approach to Wall Turbulence written by Sedat Tardu and published by John Wiley & Sons. This book was released on 2013-02-07 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wall turbulence is encountered in many technological applications as well as in the atmosphere, and a detailed understanding leading to its management would have considerable beneficial consequences in many areas. A lot of inspired work by experimenters, theoreticians, engineers and mathematicians has been accomplished over recent decades on this important topic and Statistical Approach to Wall Turbulence provides an updated and integrated view on the progress made in this area. Wall turbulence is a complex phenomenon that has several industrial applications, such as in aerodynamics, turbomachinery, geophysical flows, internal engines, etc. Several books exist on fluid turbulence, but Statistical Approach to Wall Turbulence is original in the sense that it focuses solely on the turbulent flows bounded by solid boundaries. The book covers the different physical aspects of wall turbulence, beginning with classical phenomenological aspects before advancing to recent research in the effects of the Reynolds numbers, near wall coherent structures, and wall turbulent transport process. This book would be of interest to postgraduate and undergraduate students in mechanical, chemical, and aerospace engineering, as well as researchers in aerodynamics, combustion, and all applications of wall turbulence.
Book Synopsis AIAA Journal by : American Institute of Aeronautics and Astronautics
Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2006 with total page 1024 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis IUTAM Symposium on Mechanics of Passive and Active Flow Control by : G.E.A. Meier
Download or read book IUTAM Symposium on Mechanics of Passive and Active Flow Control written by G.E.A. Meier and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: The call for papers for the rUTAM-Symposium on Mechanics of Passive and Active Flow Control brought an overwhelming response of applications for contributions. Fi nally 12 invited lectures, 48 papers and 23 posters were selected by thc Scientific Com mittee to be presented in the conference. 58 papers are published in this volume. Due to the limited number of pages available, poster presentations could not be considered for publication. The editors would like to thank all the members of the Scientific Committee for their very valuable assistance. The papers presented at the rUT AM Symposium were classified under three groups de voted to • Passive Control Methods, • Active Control Methods and • Control Concepts. This was done to contrast at first between the passive techniques where the control power is mainly supplied by the flow itself and the active techniques where the power is pro vided by external sources; the third group was devoted to control concepts for presenting methods of control theory and new techniques of flow control.
Book Synopsis Frontiers in Turbelence and Coherent Structures by : Jim Denier
Download or read book Frontiers in Turbelence and Coherent Structures written by Jim Denier and published by World Scientific. This book was released on 2007 with total page 501 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is based on the proceedings of the COSNet/CSIRO Workshop on Turbulence and Coherent Structures held at the Australian National University in Canberra in January 2006. It codifies recent developments in our understanding of the dynamics and statistical dynamics of turbulence and coherent structures in fluid mechanics, atmospheric and oceanic dynamics, plasma physics, and dynamical systems theory. It brings together articles by internationally acclaimed researchers from around the world including Dijkstra (Utrecht), Holmes (Princeton), Jimenez (UPM and Stanford), Krommes (Princeton), McComb (Edinburgh), Chong (Melbourne), Dewar (ANU), Watmuff (RMIT) and Frederiksen (CSIRO). The book will prove a useful resource for researchers as well as providing an excellent reference for graduate students working in this frontier area.
Book Synopsis Coherent Structures and Control in Wall-bounded Turbulent Flows by : Marco Atzori
Download or read book Coherent Structures and Control in Wall-bounded Turbulent Flows written by Marco Atzori and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt:
