Direct Numerical Simulation of Turbulent Mixing in a Rough-Wall Flow PDF Download
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Author: K. Tsujimoto
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
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Book Description
Rough-wall turbulent flows are more common in engineering application than smooth-wall turbulent flows. Modification of mean flow and turbulence property have been established by enormous experiments. However, details of mechanism of rough-wall turbulence has been understood little because spatial resolution is limited in experiments. Meanwhile, Direct Numerical Simulation (DNS) of a rough-wall turbulent flows which is capable of giving high resolution data requires prohibitively heavy computer power and accordingly, no other DNS data are available than those published by the present authors (Miyake et al., 1999). Our first DNS considered sandgrain roughness whose effect was implemented by profile drag based on Stokes drag and could successfully reproduce experimentally established rough-wall turbulent flow such as downward shift of straight line of logarithmic mean velocity distribution and vanishing of viscous sublayer. It was confirmed that the layer adjacent to the wall up to several tens in wall unit where smooth-wall turbulence exhibits autonomous property independent on the layer above it, is taken over by the layer having property of logarithmic layer, in rough-wall turbulence. While quasi-streamwise vortices play major role to generate high turbulent shear stress in this near-wall layer in smooth-wall turbulent flow, roughness destroy this vortical system and consequently, different mixing system which replaces the role of quasi-streamwise vortices should be found in rough-wall layer. Present work intends to investigate the turbulent mixing in the layer close to the wall of rough-wall turbulence by a DNS of more sound numerical conditions, i.e., without using any model for roughness element.
Author: K. Tsujimoto
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
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Book Description
Rough-wall turbulent flows are more common in engineering application than smooth-wall turbulent flows. Modification of mean flow and turbulence property have been established by enormous experiments. However, details of mechanism of rough-wall turbulence has been understood little because spatial resolution is limited in experiments. Meanwhile, Direct Numerical Simulation (DNS) of a rough-wall turbulent flows which is capable of giving high resolution data requires prohibitively heavy computer power and accordingly, no other DNS data are available than those published by the present authors (Miyake et al., 1999). Our first DNS considered sandgrain roughness whose effect was implemented by profile drag based on Stokes drag and could successfully reproduce experimentally established rough-wall turbulent flow such as downward shift of straight line of logarithmic mean velocity distribution and vanishing of viscous sublayer. It was confirmed that the layer adjacent to the wall up to several tens in wall unit where smooth-wall turbulence exhibits autonomous property independent on the layer above it, is taken over by the layer having property of logarithmic layer, in rough-wall turbulence. While quasi-streamwise vortices play major role to generate high turbulent shear stress in this near-wall layer in smooth-wall turbulent flow, roughness destroy this vortical system and consequently, different mixing system which replaces the role of quasi-streamwise vortices should be found in rough-wall layer. Present work intends to investigate the turbulent mixing in the layer close to the wall of rough-wall turbulence by a DNS of more sound numerical conditions, i.e., without using any model for roughness element.
Author: Fenando F. Grinstein
Publisher: Cambridge University Press
ISBN: 1107137047
Category : Science
Languages : en
Pages : 481
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Book Description
Reviews our current understanding of the subject. For graduate students and researchers in computational fluid dynamics and turbulence.
Author: Daniel Livescu
Publisher: Springer Nature
ISBN: 9811526435
Category : Technology & Engineering
Languages : en
Pages : 273
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Book Description
This book highlights recent research advances in the area of turbulent flows from both industry and academia for applications in the area of Aerospace and Mechanical engineering. Contributions include modeling, simulations and experiments meant for researchers, professionals and students in the area.
Author: Cunha Galeazzo, Flavio Cesar
Publisher: KIT Scientific Publishing
ISBN: 3731504081
Category : Chemical engineering
Languages : en
Pages : 258
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Book Description
The analysis of turbulent mixing in complex turbulent flows is a challenging task. The effective mixing of entrained fluids to a molecular level is a vital part of the dynamics of turbulent flows, especially when combustion is involved. The work has shown the limitations of the steady-state simulations and acknowledged the need of applying high-fidelity unsteady methods for the calculation of flows with pronounced unsteadiness promoted by large-scale coherent structures or other sources.
Author: T. B. Gatski
Publisher: Oxford University Press, USA
ISBN: 0195106431
Category : Fluid dynamics
Languages : en
Pages : 329
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Book Description
This book provides students and researchers in fluid engineering with an up-to-date overview of turbulent flow research in the areas of simulation and modeling. A key element of the book is the systematic, rational development of turbulence closure models and related aspects of modern turbulent flow theory and prediction. Starting with a review of the spectral dynamics of homogenous and inhomogeneous turbulent flows, succeeding chapters deal with numerical simulation techniques, renormalization group methods and turbulent closure modeling. Each chapter is authored by recognized leaders in their respective fields, and each provides a thorough and cohesive treatment of the subject.
Author: G. Biswas
Publisher: CRC Press
ISBN: 9780849310140
Category : Technology & Engineering
Languages : en
Pages : 478
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Book Description
This book allows readers to tackle the challenges of turbulent flow problems with confidence. It covers the fundamentals of turbulence, various modeling approaches, and experimental studies. The fundamentals section includes isotropic turbulence and anistropic turbulence, turbulent flow dynamics, free shear layers, turbulent boundary layers and plumes. The modeling section focuses on topics such as eddy viscosity models, standard K-E Models, Direct Numerical Stimulation, Large Eddy Simulation, and their applications. The measurement of turbulent fluctuations experiments in isothermal and stratified turbulent flows are explored in the experimental methods section. Special topics include modeling of near wall turbulent flows, compressible turbulent flows, and more.
Author: Amid Ansari
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Stephen B. Pope
Publisher:
ISBN:
Category :
Languages : en
Pages : 7
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Book Description
Mixing in simple turbulent flows has been investigating using 64 cubed and 128 cubed Direct Numerical Simulations. In turbulent combustion, mixing by molecular transport is an essential process that is not well understood. Because mixing occurs on the smallest length and time scales it is difficult to study experimentally. Instead, we have employed direct numerical simulation of turbulence, initially for a conserved passive scalar in homogeneous isotropic turbulence. The Eulerian velocity and scalar fields are calculated from the exact evolution equations, and both Eulerian and Lagrangian statistics are deduced from the computed fields. A particle-tracking scheme, needed to extract Lagrangian information, has been implemented. The testing of a number of such particle tracking schemes has been completed with good results: accurate Lagrangian information can be extracted at a modest computational cost. In order to study processes in stationary turbulence, a forcing algorithm has been implemented. Tests on this scheme are complete, again with good results: the small scales are unaffected by the details of the forcing. Studies have been performed of: the mixing of a passive scalar; Lagrangian velocity, Acceleration and dissipation statistics; and Mixing and combustion problems viewed in terms of surfaces.
Author: B Mutlu Sumer
Publisher: World Scientific
ISBN: 9813234326
Category : Technology & Engineering
Languages : en
Pages : 758
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Book Description
This book discusses the subject of turbulence encountered in coastal and civil engineering.The primary aim of the book is to describe turbulence processes including transition to turbulence; mean and fluctuating flows in channels/pipes, and in currents; wave boundary layers (including boundary layers under solitary waves); streaming processes in wave boundary layers; turbulence processes in breaking waves including breaking solitary waves; turbulence processes such as bursting process and their implications for sediment transport; flow resistance in steady and wave boundary layers; and turbulent diffusion and dispersion processes in the coastal and river environment, including sediment transport due to diffusion/dispersion.Both phenomenological and statistical theories are described in great detail. Turbulence modelling is also described, and several examples for modelling of turbulence in steady flow and wave boundary layers are presented.The book ends with a chapter containing hands-on exercises on a wide variety of turbulent flows including experimental study of turbulence in an open-channel flow, using Laser Doppler Anemometry; Statistical, correlation and spectral analysis of turbulent air jet flow; Turbulence modelling of wave boundary layer flows; and numerical modelling of dispersion in a turbulent boundary layer, a set of exercises used by the authors in their Masters classes over many years.Although the book is essentially intended for professionals and researchers in the area of Coastal and Civil Engineering, and as a text book for graduate/post graduate students, the contents of the book will, however, additionally provide sufficient background in the study of turbulent flows relevant to many other disciplines, such as Wind Engineering, Mechanical Engineering, and Environmental Engineering.
Author: J. H. Ferziger
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 172
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Book Description
The five major categories of this paper are: Correlations, Integral methods, Reynolds-averaged equations, large eddy simulation, and full simulation.
