Subgrid-scale Modeling for Fluid Flow Simulations Via the Variational Multiscale Method

Subgrid-scale Modeling for Fluid Flow Simulations Via the Variational Multiscale Method PDF Author: Luca Mazzei
Publisher:
ISBN:
Category :
Languages : en
Pages : 122

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Subgrid-scale Modeling for Fluid Flow Simulations Via the Variational Multiscale Method

Subgrid-scale Modeling for Fluid Flow Simulations Via the Variational Multiscale Method PDF Author: Luca Mazzei
Publisher:
ISBN:
Category :
Languages : en
Pages : 122

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Variational Multiscale Method for Stochastic Thermal and Fluid Flow Problems

Variational Multiscale Method for Stochastic Thermal and Fluid Flow Problems PDF Author: Badrinarayanan Velamur Asokan
Publisher:
ISBN:
Category :
Languages : en
Pages : 390

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Nonlinear Subgrid Finite Element Models for Low Mach Number Flows Coupled with Radiative Heat Transfer

Nonlinear Subgrid Finite Element Models for Low Mach Number Flows Coupled with Radiative Heat Transfer PDF Author: Matías Avila
Publisher:
ISBN:
Category :
Languages : en
Pages : 208

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Book Description
The general description of a fluid flow involves the solution of the compressible Navier-Stokes equations, a very complex problem whose mathematical structure is not well understood. It is widely accepted that these equations provide an accurate description of any problem in fluid mechanics which may present many different nonlinear physical mechanisms. Depending on the physics of the problem under consideration, different simplified models neglecting some physical mechanisms can be derived from asymptotic analysis. On the other hand, radiative heat transfer can strongly interact with convection in high temperature flows, and neglecting its effects may have significant consequences in the overall predictions. Problems as fire scenarios emphasized the need for an evaluation of the effect of radiative heat transfer. This work is directed to strongly thermally coupled low Mach number flows with radiative heat transfer. The complexity of these mathematical problem makes their numerical solution very difficult. Despite the important difference in the treatment of the incompressibility, the low Mach number equations present the same mathematical structure as the incompressible Navier-Stokes equations, in the sense that the mechanical pressure is determined from the mass conservation constraint. Consequently the same type of numerical instabilities can be found, namely, the problem of compatibility conditions between the velocity and pressure finite element spaces, and the instabilities due to convection dominated flows. These instabilities can be avoided by the use of stabilization techniques. Many stabilization techniques used nowadays are based on the variational multiscale method, in which a decomposition of the approximating space into a coarse scale resolvable part and a fine scale subgrid part is performed. The modeling of the subgrid scale and its influence leads to a modified coarse scale problem providing stability. The quality of the final approximation (accuracy, efficiency) depends on the particular model. The extension of these techniques to nonlinear and coupled problems is presented. The distinctive features of our approach are to consider the subscales as transient and to keep the scale splitting in all the nonlinear terms appearing in the finite element equations and in the subgrid scale model. The first ingredient permits to obtain an improved time discretization scheme(higher accuracy, better stability). The second ingredient permits to prove global conservation properties, being also responsible of the higher accuracy of the method. This ingredient is intimately related to the problem of thermal turbulence modeling from a strictly numerical point of view. The capability for the simulation of turbulent flows is a measure of the ability of modeling the effect of the subgrid flow structures over the coarser ones. The performance of the model in predicting the behavior of turbulent flows is demonstrated. The radiation transport equation has been also approximated within the variational multiscale framework, the design and analysis of stabilized finite element methods is presented.

Geometric Modeling with Splines

Geometric Modeling with Splines PDF Author: Elaine Cohen
Publisher: CRC Press
ISBN: 1439864209
Category : Computers
Languages : en
Pages : 638

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Book Description
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

Encyclopedia of Computational Mechanics

Encyclopedia of Computational Mechanics PDF Author: Erwin Stein
Publisher:
ISBN:
Category : Dynamics
Languages : en
Pages : 870

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

Multiscale and Multiresolution Approaches in Turbulence

Multiscale and Multiresolution Approaches in Turbulence PDF Author: Pierre Sagaut
Publisher: World Scientific
ISBN: 1848169876
Category : Science
Languages : en
Pages : 446

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Book Description
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.

Multiscale And Multiresolution Approaches In Turbulence - Les, Des And Hybrid Rans/les Methods: Applications And Guidelines (2nd Edition)

Multiscale And Multiresolution Approaches In Turbulence - Les, Des And Hybrid Rans/les Methods: Applications And Guidelines (2nd Edition) PDF Author: Pierre Sagaut
Publisher: World Scientific
ISBN: 1848169884
Category : Mathematics
Languages : en
Pages : 446

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Book Description
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./a

A Variational Multiscale Method for Turbulent Flow Simulation with Adaptive Large Scale Space

A Variational Multiscale Method for Turbulent Flow Simulation with Adaptive Large Scale Space PDF Author: Volker John
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Frontiers in Computational Fluid-Structure Interaction and Flow Simulation

Frontiers in Computational Fluid-Structure Interaction and Flow Simulation PDF Author: Tayfun E. Tezduyar
Publisher: Springer
ISBN: 3319964690
Category : Mathematics
Languages : en
Pages : 493

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Book Description
Computational fluid-structure interaction and flow simulation are challenging research areas that bring solution and analysis to many classes of problems in science, engineering, and technology. Young investigators under the age of 40 are conducting much of the frontier research in these areas, some of which is highlighted in this book. The first author of each chapter took the lead role in carrying out the research presented. The topics covered include Computational aerodynamic and FSI analysis of wind turbines, Simulating free-surface FSI and fatigue-damage in wind-turbine structural systems, Aorta flow analysis and heart valve flow and structure analysis, Interaction of multiphase fluids and solid structures, Computational analysis of tire aerodynamics with actual geometry and road contact, and A general-purpose NURBS mesh generation method for complex geometries. This book will be a valuable resource for early-career researchers and students — not only those interested in computational fluid-structure interaction and flow simulation, but also other fields of engineering and science, including fluid mechanics, solid mechanics and computational mathematics – as it will provide them with inspiration and guidance for conducting their own successful research. It will also be of interest to senior researchers looking to learn more about successful research led by those under 40 and possibly offer collaboration to these researchers.

Computational Aerodynamic Modeling of Aerospace Vehicles

Computational Aerodynamic Modeling of Aerospace Vehicles PDF Author: Mehdi Ghoreyshi
Publisher: MDPI
ISBN: 3038976105
Category : Technology & Engineering
Languages : en
Pages : 294

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Book Description
Currently, the use of computational fluid dynamics (CFD) solutions is considered as the state-of-the-art in the modeling of unsteady nonlinear flow physics and offers an early and improved understanding of air vehicle aerodynamics and stability and control characteristics. This Special Issue covers recent computational efforts on simulation of aerospace vehicles including fighter aircraft, rotorcraft, propeller driven vehicles, unmanned vehicle, projectiles, and air drop configurations. The complex flow physics of these configurations pose significant challenges in CFD modeling. Some of these challenges include prediction of vortical flows and shock waves, rapid maneuvering aircraft with fast moving control surfaces, and interactions between propellers and wing, fluid and structure, boundary layer and shock waves. Additional topic of interest in this Special Issue is the use of CFD tools in aircraft design and flight mechanics. The problem with these applications is the computational cost involved, particularly if this is viewed as a brute-force calculation of vehicle’s aerodynamics through its flight envelope. To make progress in routinely using of CFD in aircraft design, methods based on sampling, model updating and system identification should be considered.