Geometric Modeling with Splines

Geometric Modeling with Splines
Author: Elaine Cohen
Publisher: CRC Press
Total Pages: 638
Release: 2001-07-18
Genre: Computers
ISBN: 1439864209

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Written by researchers who have helped found and shape the field, this book is a definitive introduction to geometric modeling. The authors present all of the necessary techniques for curve and surface representations in computer-aided modeling with a focus on how the techniques are used in design. They achieve a balance between mathematical rigor

Finite Element Methods for Incompressible Flow Problems

Finite Element Methods for Incompressible Flow Problems
Author: Volker John
Publisher: Springer
Total Pages: 816
Release: 2016-10-27
Genre: Mathematics
ISBN: 3319457500

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This book explores finite element methods for incompressible flow problems: Stokes equations, stationary Navier-Stokes equations and time-dependent Navier-Stokes equations. It focuses on numerical analysis, but also discusses the practical use of these methods and includes numerical illustrations. It also provides a comprehensive overview of analytical results for turbulence models. The proofs are presented step by step, allowing readers to more easily understand the analytical techniques.

A Review of Variational Multiscale Methods for the Simulation of Turbulent Incompressible Flows

A Review of Variational Multiscale Methods for the Simulation of Turbulent Incompressible Flows
Author: Naveed Ahmed
Publisher:
Total Pages:
Release: 2015
Genre:
ISBN:

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Various realizations of variational multiscale (VMS) methods for simulating turbulent incompressible flows have been proposed in the past fifteen years. All of these realizations obey the basic principles of VMS methods: They are based on the variational formulation of the incompressible Navier-Stokes equations and the scale separation is defined by projections. However, apart from these common basic features, the various VMS methods look quite different. In this review, the derivation of the different VMS methods is presented in some detail and their relation among each other and also to other discretizations is discussed. Another emphasis consists in giving an overview about known results from the numerical analysis of the VMS methods. A few results are presented in detail to highlight the used mathematical tools. Furthermore, the literature presenting numerical studies with the VMS methods is surveyed and the obtained results are summarized.

Large Scale Finite Element Solvers for the Large Eddy Simulation of Incompressible Turbulent Flows

Large Scale Finite Element Solvers for the Large Eddy Simulation of Incompressible Turbulent Flows
Author: Oriol Colomés Gené
Publisher:
Total Pages: 261
Release: 2016
Genre:
ISBN:

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In this thesis we have developed a path towards large scale Finite Element simulations of turbulent incompressible flows. We have assessed the performance of residual-based variational multiscale (VMS) methods for the large eddy simulation (LES) of turbulent incompressible flows. We consider VMS models obtained by different subgrid scale approximations which include either static or dynamic subscales, linear or nonlinear multiscale splitting, and different choices of the subscale space. We show that VMS thought as an implicit LES model can be an alternative to the widely used physical-based models. This method is traditionally combined with equal-order velocity-pressure pairs, since it provides pressure stabilization. In this work, we also consider a different approach, based on inf-sup stable elements and convection-only stabilization. In order to do so, we define a symmetric projection stabilization of the convective term using an orthogonal subscale decomposition. The accuracy and efficiency of this method compared with residual-based algebraic subgrid scales and orthogonal subscales methods for equal-order interpolation is also assessed in this thesis. Furthermore, we propose Runge-Kutta time integration schemes for the incompressible Navier-Stokes equations with two salient properties. First, velocity and pressure computations are segregated at the time integration level, without the need to perform additional fractional step techniques that spoil high orders of accuracy. Second, the proposed methods keep the same order of accuracy for both velocities and pressures. Precisely, the symmetric projection stabilization approach is suitable for segregated Runge-Kutta time integration schemes. This combination, together with the use of block-preconditioning techniques, lead to elasticity-type and Laplacian-type problems that can be optimally preconditioned using the balancing domain decomposition by constraints preconditioners. The weak scalability of this formulation have been demonstrated in this document. Additionally, we also contemplate the weak imposition of the Dirichlet boundary conditions for wall-bounded turbulent flows. Four well known problems have been mainly considered for the numerical experiments: the decay of homogeneous isotropic turbulence, the Taylor-Green vortex problem, the turbulent flow in a channel and the turbulent flow around an airfoil.

Encyclopedia of Computational Mechanics

Encyclopedia of Computational Mechanics
Author: Erwin Stein
Publisher:
Total Pages: 870
Release: 2004
Genre: Dynamics
ISBN:

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The Encyclopedia of Computational Mechanics provides a comprehensive collection of knowledge about the theory and practice of computational mechanics.

Mathematical and Numerical Foundations of Turbulence Models and Applications

Mathematical and Numerical Foundations of Turbulence Models and Applications
Author: Tomás Chacón Rebollo
Publisher: Springer
Total Pages: 530
Release: 2014-06-17
Genre: Mathematics
ISBN: 1493904558

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With applications to climate, technology, and industry, the modeling and numerical simulation of turbulent flows are rich with history and modern relevance. The complexity of the problems that arise in the study of turbulence requires tools from various scientific disciplines, including mathematics, physics, engineering and computer science. Authored by two experts in the area with a long history of collaboration, this monograph provides a current, detailed look at several turbulence models from both the theoretical and numerical perspectives. The k-epsilon, large-eddy simulation and other models are rigorously derived and their performance is analyzed using benchmark simulations for real-world turbulent flows. Mathematical and Numerical Foundations of Turbulence Models and Applications is an ideal reference for students in applied mathematics and engineering, as well as researchers in mathematical and numerical fluid dynamics. It is also a valuable resource for advanced graduate students in fluid dynamics, engineers, physical oceanographers, meteorologists and climatologists.

Numerical Analysis of a Variational Multiscale Method for Turbulence

Numerical Analysis of a Variational Multiscale Method for Turbulence
Author: Songül Kaya Merdan
Publisher: LAP Lambert Academic Publishing
Total Pages: 80
Release: 2011-10
Genre:
ISBN: 9783845432083

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Despite efforts of more than centuries, turbulence phenomena is categorized as an unsolved problem. Turbulence is part of everyday's life. The majority of flows of industrial and technological applications are turbulent; natural flows are invariably so. There are many important and interesting physical phenomena which are connected with turbulent flows. Turbulence is observed in natural and engineering applications such as in weather prediction, air pollution, water pollution, aerodynamics and heat exchangers. This work considers an accurate and reliable solutions of turbulent flows. It is concerned with one of the most promising approaches to the numerical simulation of turbulent flows, the subgrid eddy viscosity models. We analyze both continuous and discontinuous finite element approximation of the new subgrid eddy viscosity model. This approach has the advantage that the diffusivity is introduced only on the small scales of the flow. Numerical test shows the new stabilization technique is robust and efficient in solving Navier-Stokes equations for a wide range of Reynolds numbers.

Multiscale and Multiresolution Approaches in Turbulence

Multiscale and Multiresolution Approaches in Turbulence
Author: Pierre Sagaut
Publisher: World Scientific
Total Pages: 446
Release: 2013
Genre: Science
ISBN: 1848169876

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The book aims to provide the reader with an updated general presentation of multiscale/multiresolution approaches in turbulent flow simulations. All modern approaches (LES, hybrid RANS/LES, DES, SAS) are discussed and recast in a global comprehensive framework. Both theoretical features and practical implementation details are addressed. Some full scale applications are described, to provide the reader with relevant guidelines to facilitate a future use of these methods.