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Author : Jean-Marc Y. C. Robin
Publisher :
ISBN 13 :
Total Pages : 106 pages
Book Rating : 4.:/5 (272 download)
Download or read book Discrete Explicit Filtering for LES of Compressible Turbulent Flow written by Jean-Marc Y. C. Robin and published by . This book was released on 2007 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Deconinck Willem
Publisher : LAP Lambert Academic Publishing
ISBN 13 : 9783659529887
Total Pages : 0 pages
Book Rating : 4.5/5 (298 download)
Download or read book Design and Application of Discrete Explicit Filters written by Deconinck Willem and published by LAP Lambert Academic Publishing. This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the context of Large Eddy Simulation (LES) of turbulent flows, there is a current need to compare and evaluate different proposed subfilter-scale models in order to assess their suitability for various applications. In order to carefully compare subfilter-scale models and compare LES predictions to Direct Numerical Simulation (DNS) results (the latter would be helpful in the comparison and validation of models), there is a real need for a "grid-independent" LES capability and explicit filtering methods offer one means by which this may be achieved. Advantages of explicit filtering are that it provides a means for eliminating aliasing errors, allows for the direct control of commutation errors, and most importantly allows a decoupling between the mesh spacing and the filter width which is the primary reason why there are difficulties in comparing LES solutions obtained on different grids. This book considers the design and assessment of discrete explicit filters and their application to isotropic turbulence prediction. This book was submitted for the degree of Masters of Applied Science at the Graduate Department of Aerospace Engineering at the University of Toronto.
Author : Willem Deconinck
Publisher :
ISBN 13 : 9780494587713
Total Pages : 95 pages
Book Rating : 4.5/5 (877 download)
Download or read book Design and Application of Discrete Explicit Filters for Large Eddy Simulation of Compressible Turbulent Flows written by Willem Deconinck and published by . This book was released on 2008 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the context of Large Eddy Simulation (LES) of turbulent flows, there is a current need to compare and evaluate different proposed subfilter-scale models. In order to carefully compare subfilter-scale models and compare LES predictions to Direct Numerical Simulation (DNS) results (the latter would be helpful in the comparison and validation of models), there is a real need for a "grid-independent" LES capability and explicit filtering methods offer one means by which this may be achieved. Advantages of explicit filtering are that it provides a means for eliminating aliasing errors, allows for the direct control of commutation errors, and most importantly allows a decoupling between the mesh spacing and the filter width which is the primary reason why there are difficulties in comparing LES solutions obtained on different grids. This thesis considers the design and assessment of discrete explicit filters and their application to isotropic turbulence prediction.
Author : Aleix Baez Vidal
Publisher :
ISBN 13 :
Total Pages : 166 pages
Book Rating : 4.:/5 (112 download)
Download or read book Filtering in the Numerical Simulation of Turbulent Compressible Flow with Sysmmetry Preserving Discretizations written by Aleix Baez Vidal and published by . This book was released on 2019 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present thesis investigates how explicit filters can be useful in numerical simulations of turbulent, compressible flow with symmetry preserving discretizations. Such explicit filters provide stability to simulations with shocks, provide stability to low-dissipation schemes on smooth flows and are used as test filters in LES turbulence models such as the Variational Multi-Scale eddy viscosity model or regularization models. The present thesis is a step forward in four main aspects. First, a comparative study of the Symmetry Preserving schemes for compressible flow is conducted. It shows that Rozema's scheme is more stable and accurate than the other schemes compiled fromthe literature. A sligh tmodification on this scheme is presented and shown to be more stable and accurate in unstructured meshes, but lesser accurate and stable in uniform, structured meshes. Second, a theoretical analysis of the properties of filters for CFD and their consequences on the derivation of the LES equations is conducted. The analysis shows how the diffusive properties of filters are necessary for the consistency of the model. Third, a study of explicit filtering on discrete variables identifies the necessary constraints for the fulfillment of the discrete counterpart of the filter properties. It puts emphases on the different possibilities when requiring the filters to be diffusive. After it, a new family of filters has been derived and tested in newly developed tests that allow the independent study of each property. And last, an algorithm to couple adaptive filtering with time integration is reported and tested on the 2D Isentropic Vortex and on the Taylor-Green vortex problem. Filtering is shown to enhance stability at the cost of locally adding diffusion. This saves the simulations from being diffusive everywhere. The resulting methodology is also shown to be potentially useful for shock-capturing purposes with the simulation of a shock-tube in a fully unstructured mesh.
Author : Alvaro A. Aldama
Publisher : Springer Science & Business Media
ISBN 13 : 3642840914
Total Pages : 410 pages
Book Rating : 4.6/5 (428 download)
Download or read book Filtering Techniques for Turbulent Flow Simulation written by Alvaro A. Aldama and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: 1. 1 Scope of the Study The detailed and reasonably accurate computation of large scale turbulent flows has become increasingly important in geophysical and engi neering applications in recent years. The definition of water quality management policies for reservoirs, lakes, estuaries, and coastal waters, as well as the design of cooling ponds and solar ponds, requires an ade quate quantitative description of turbulent flows. When the diffusion of some tracer (be it active, such as temperature or salinity, or passive, such as dissolved oxygen) is of relevance to a specific application, the proper determination of the effects of turbulent transport processes has paramount importance. Thus, for instance, the proper understanding of lake and reservoir dynamics requires, as a first step, the ability to simulate turbulent flows. Applications in other areas of geophysical research, such as meteorology and oceanography are easily identified and large in number. It should be stressed that, in this context, the analyst seeks predictive ability to a certain extent. Accordingly, the need for simulation models that closely resemble the natural processes to be repre sented has recently become more evident. Since the late 1960s considerable effort has been devoted to the development of models for the simulation of complex turbulent flows. This has resulted in the establishment of two approaches which have been, or 2 have the potential for being, applied to problems of engineering and geophysical interest.
Author : Luigi Carlo Berselli
Publisher : Springer Science & Business Media
ISBN 13 : 9783540263166
Total Pages : 378 pages
Book Rating : 4.2/5 (631 download)
Download or read book Mathematics of Large Eddy Simulation of Turbulent Flows written by Luigi Carlo Berselli and published by Springer Science & Business Media. This book was released on 2006 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: The LES-method is rapidly developing in many practical applications in engineering The mathematical background is presented here for the first time in book form by one of the leaders in the field
Author : Sintia Bejatovic
Publisher :
ISBN 13 : 9780494762387
Total Pages : 174 pages
Book Rating : 4.7/5 (623 download)
Download or read book Evaluation of Discrete Explicit Filtering for an Approximate Deconvolution Approach to LES. written by Sintia Bejatovic and published by . This book was released on 2011 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the study of computational turbulence, the success of Large Eddy Simulation (LES) is largely determined by the quality of the sub-filter scale (SFS) model and the properties of the filter used to introduce resolved and unresolved length scales. Additionally, the SFS model and filter are strongly linked, in such a way that the filter process cannot be too contaminated with aliasing errors, as this would cause an inaccurate representation of the flow. One way to alleviate this issue is to use explicit filtering, so that better control over the filter may be achieved, and filter operator errors can be then controlled to a desired order of accuracy. One large advantage to using an explicit filter is that the mathematical definition of the filter may be exploited when considering various SFS models or even different LES techniques. Approximate deconvolution is a technique used in LES, which performs an inverse filtering operation to partly restore the original unfiltered solution. This thesis considers a form of structural modeling, known as approximate deconvolution, to perform a large-eddy simulation of homogeneous, isotropic turbulence. In particular, the discrete explicit filtering technique will be used to perform the deconvolution, and numerical results will show how the approximate solution may be used to perform LES.
Author : Stéphane Vincent
Publisher : Springer Nature
ISBN 13 : 3031092651
Total Pages : 314 pages
Book Rating : 4.0/5 (31 download)
Download or read book Small Scale Modeling and Simulation of Incompressible Turbulent Multi-Phase Flow written by Stéphane Vincent and published by Springer Nature. This book was released on 2022-10-06 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides basic and recent research insights concerning the small scale modeling and simulation of turbulent multi-phase flows. By small scale, it has to be understood that the grid size for the simulation is smaller than most of the physical time and space scales of the problem. Small scale modeling of multi-phase flows is a very popular topic since the capabilities of massively parallel computers allows to go deeper into the comprehension and characterization of realistic flow configurations and at the same time, many environmental and industrial applications are concerned such as nuclear industry, material processing, chemical reactors, engine design, ocean dynamics, pollution and erosion in rivers or on beaches. The work proposes a complete and exhaustive presentation of models and numerical methods devoted to small scale simulation of incompressible turbulent multi-phase flows from specialists of the research community. Attention has also been paid to promote illustrations and applications, multi-phase flows and collaborations with industry. The idea is also to bring together developers and users of different numerical approaches and codes to share their experience in the development and validation of the algorithms and discuss the difficulties and limitations of the different methods and their pros and cons. The focus will be mainly on fixed-grid methods, however adaptive grids will be also partly broached, with the aim to compare and validate the different approaches and models.
Author : Jiri Blazek
Publisher : Butterworth-Heinemann
ISBN 13 : 0128011726
Total Pages : 466 pages
Book Rating : 4.1/5 (28 download)
Download or read book Computational Fluid Dynamics written by Jiri Blazek and published by Butterworth-Heinemann. This book was released on 2015-04-23 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Fluid Dynamics: Principles and Applications, Third Edition presents students, engineers, and scientists with all they need to gain a solid understanding of the numerical methods and principles underlying modern computation techniques in fluid dynamics. By providing complete coverage of the essential knowledge required in order to write codes or understand commercial codes, the book gives the reader an overview of fundamentals and solution strategies in the early chapters before moving on to cover the details of different solution techniques. This updated edition includes new worked programming examples, expanded coverage and recent literature regarding incompressible flows, the Discontinuous Galerkin Method, the Lattice Boltzmann Method, higher-order spatial schemes, implicit Runge-Kutta methods and parallelization. An accompanying companion website contains the sources of 1-D and 2-D Euler and Navier-Stokes flow solvers (structured and unstructured) and grid generators, along with tools for Von Neumann stability analysis of 1-D model equations and examples of various parallelization techniques. - Will provide you with the knowledge required to develop and understand modern flow simulation codes - Features new worked programming examples and expanded coverage of incompressible flows, implicit Runge-Kutta methods and code parallelization, among other topics - Includes accompanying companion website that contains the sources of 1-D and 2-D flow solvers as well as grid generators and examples of parallelization techniques
Author : Peter D. Lax
Publisher : SIAM
ISBN 13 : 0898711770
Total Pages : 55 pages
Book Rating : 4.8/5 (987 download)
Download or read book Hyperbolic Systems of Conservation Laws and the Mathematical Theory of Shock Waves written by Peter D. Lax and published by SIAM. This book was released on 1973-01-01 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with the mathematical side of the theory of shock waves. The author presents what is known about the existence and uniqueness of generalized solutions of the initial value problem subject to the entropy conditions. The subtle dissipation introduced by the entropy condition is investigated and the slow decay in signal strength it causes is shown.
Author : Fernando F. Grinstein
Publisher : Cambridge University Press
ISBN 13 : 9780521869829
Total Pages : 578 pages
Book Rating : 4.8/5 (698 download)
Download or read book Implicit Large Eddy Simulation written by Fernando F. Grinstein and published by Cambridge University Press. This book was released on 2007-07-30 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt: The numerical simulation of turbulent flows is a subject of great practical importance to scientists and engineers. The difficulty in achieving predictive simulations is perhaps best illustrated by the wide range of approaches that have been developed and are still being used by the turbulence modeling community. In this book the authors describe one of these approaches, Implicit Large Eddy Simulation (ILES). ILES is a relatively new approach that combines generality and computational efficiency with documented success in many areas of complex fluid flow. This book synthesizes the theoretical basis of the ILES methodology and reviews its accomplishments. ILES pioneers and lead researchers combine here their experience to present a comprehensive description of the methodology. This book should be of fundamental interest to graduate students, basic research scientists, as well as professionals involved in the design and analysis of complex turbulent flows.
Author : Robert Moser
Publisher : Elsevier
ISBN 13 : 032399833X
Total Pages : 568 pages
Book Rating : 4.3/5 (239 download)
Download or read book Numerical Methods in Turbulence Simulation written by Robert Moser and published by Elsevier. This book was released on 2022-11-30 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical Methods in Turbulence Simulation provides detailed specifications of the numerical methods needed to solve important problems in turbulence simulation. Numerical simulation of turbulent fluid flows is challenging because of the range of space and time scales that must be represented. This book provides explanations of the numerical error and stability characteristics of numerical techniques, along with treatments of the additional numerical challenges that arise in large eddy simulations. Chapters are written as tutorials by experts in the field, covering specific both contexts and applications. Three classes of turbulent flow are addressed, including incompressible, compressible and reactive, with a wide range of the best numerical practices covered. A thorough introduction to the numerical methods is provided for those without a background in turbulence, as is everything needed for a thorough understanding of the fundamental equations. The small scales that must be resolved are generally not localized around some distinct small-scale feature, but instead are distributed throughout a volume. These characteristics put particular strain on the numerical methods used to simulate turbulent flows. - Includes a detailed review of the numerical approximation issues that impact the simulation of turbulence - Provides a range of examples of large eddy simulation techniques - Discusses the challenges posed by boundary conditions in turbulence simulation and provides approaches to addressing them
Author : Sharath Girimaji
Publisher : Springer
ISBN 13 : 331915141X
Total Pages : 481 pages
Book Rating : 4.3/5 (191 download)
Download or read book Progress in Hybrid RANS-LES Modelling written by Sharath Girimaji and published by Springer. This book was released on 2015-02-20 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers the proceedings of the Fifth Symposium on Hybrid RANS-LES Methods, which was held on March 19-21 in College Station, Texas, USA. The different chapters, written by leading experts, reports on the most recent developments in flow physics modelling, and gives a special emphasis to industrially relevant applications of hybrid RANS-LES methods and other turbulence-resolving modelling approaches. The book addresses academic researchers, graduate students, industrial engineers, as well as industrial R&D managers and consultants dealing with turbulence modelling, simulation and measurement, and with multidisciplinary applications of computational fluid dynamics (CFD), such as flow control, aero-acoustics, aero-elasticity and CFD-based multidisciplinary optimization. It discusses in particular advanced hybrid RANS-LES methods. Further topics include wall-modelled Large Eddy Simulation (WMLES) methods, embedded LES, and a comparison of the LES methods with both hybrid RANS-LES and URANS methods. Overall, the book provides readers with a snapshot on the state-of-the-art in CFD and turbulence modelling, with a special focus to hybrid RANS-LES methods and their industrial applications.
Author : A. Haselbacher
Publisher :
ISBN 13 :
Total Pages : 8 pages
Book Rating : 4.:/5 (742 download)
Download or read book Discrete Filtering on Unstructured Grids Based on Least-Squares Gradient Reconstruction written by A. Haselbacher and published by . This book was released on 2001 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The equations for Large-Eddy Simulation (LES) of turbulent flows are formally derived by applying a low-pass filter to the Navier-Stokes equations. In doing so, it is often tacitly assumed that the filtering and differentiation operations commute. This assumption is invalid if the filter width is not uniform as is the case if wall-bounded flows are computed unless special filter operators are constructed, see, e.g, Vasilyev et at. (1998). The goal of the present work is to develop a simpler filtering method than that of Marsden et al. (2000). The new filtering method is based on the following observation: The conditions for filtering a function to a given order of commutation error derived by Vasilyev et al. (1998) are formally identical to the conditions for reconstructing the gradient of a function to a given order of truncation error. In other words, the construction of filtering operators may be reinterpreted as the construction of, suitably reformulated, gradient-reconstruction methods. This apparently trivial observation has important consequences because the reconstruction of gradients is central to many flow-solution methods on unstructured grids and is well understood.
Author : Jiri Blazek
Publisher : Elsevier
ISBN 13 : 0080545548
Total Pages : 461 pages
Book Rating : 4.0/5 (85 download)
Download or read book Computational Fluid Dynamics: Principles and Applications written by Jiri Blazek and published by Elsevier. This book was released on 2001-05-11 with total page 461 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Fluid Dynamics: Principles and Applications
Author : Mostafa Najafiyazdi
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (119 download)
Download or read book Large-Eddy Simulations on Unstructured Grids Using Explicit Differential Filters in Approximate Deconvolution Models written by Mostafa Najafiyazdi and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "In Computational Aeroacoustic (CAA) applications of Large-Eddy Simulations (LES), accurate control over turbulent kinetic energy (TKE) dissipation is needed to minimize aliasing and obtain accurate broad-band noise estimations. Among different LES approaches, Approximate Deconvolution Models (ADM) allow direct control of the TKE dissipation rate for the resolvable wavenumber scales. This control is obtained by applying an explicitly defined spatial filter on the computed flow fields. InADM schemes, filtered Navier-Stokes equations are used where the filtering operator is explicitly defined. Approximate deconvolution approaches are used to estimate the unfiltered quantities used in constructing the nonlinear flux terms. Given a filter operator, the energy dissipation associated with filtering can be quantified. ADM has been successfully applied on structured grids using discrete high-order filter operators. Its application on unstructured grid has been very limited due to lack of a proper filter.The objective of the present work was to extend the application of Approximate Deconvolution Models (ADM) for LES on unstructured grids by using explicit differential filters. Germano’s elliptic differential filter was successfully extended to include two free parameters. One ensured full attenuation at grid cut-off wavenumber, preventing aliasing due to LES and stabilizing the numerical scheme. The other controlled the filter cut-off wavenumber. The discretized formulation of this differential filter was developed for two- and three-dimensional elements. Dissipation and dispersion properties of the discrete differential filter were investigated in detail.A second-order classical finite element method (FEM) was used for spatial discretization of the compressible Navier-Stokes equations. Time integration was performed through the use of the standard fourth-order explicit Runge-Kutta scheme. Interpolation on high resolution grids was used to obtain the fast Fourier transform (FFT) of the flow fields on perturbed and unstructured grids.Decaying isotropic homogeneous turbulence at Reynolds number 3, 400 was modeled on both structured and unstructured grids. Results were compared to a reference direct numerical simulation (DNS) and other LES results reported in the literature. The effect of mesh anisotropy on the newly proposed differential filter performance was studied. It was observed that stable and sufficiently accurate LES results could be obtained on unstructured grids, even in the presence of highly skewed elements. Careful examination of the dissipation rate in the resolved wavenumbers suggested that grid anisotropy induces different cut-off wavenumbers in different directions resulting in higher dissipation rates than those obtained on an isotropic mesh.Taylor-Green vortex (TGV) was also studied as an excellent canonical problem for laminar to turbulence transition of a flow. LES simulations using the ADM framework were conducted in which the filter extended to three-dimensional elements was used. Investigative studies on the ADM order, the ADM under-relaxation coefficient, the degree of anisotropy in the grid, and grid resolution were performed to benchmark the filter performance in conjunction with ADM. Finally, an LES of TGV on a fully unstructured grid was performed showing the range of application of the proposed filter"--
Author : Center for Turbulence Research (U.S.)
Publisher :
ISBN 13 :
Total Pages : 434 pages
Book Rating : 4.:/5 (56 download)
Download or read book Annual Research Briefs ... written by Center for Turbulence Research (U.S.) and published by . This book was released on 2011 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt:
