November 26, 2020

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Direct Numerical Simulation and Multiscale Modelling

Direct Numerical Simulation and Multiscale Modelling
Author : Kai Luo
Publisher : Academic Press
Release Date : 2021-04
Category :
Total pages :129
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Direct Numerical Simulation and Multiscale Modelling provides a unified description of DNS, LES and RANS in the context of broader modelling and simulation practice. The relevance of these techniques to flow, turbulence, combustion and multiphysics is explained to help readers apply them to a wide range of research topics. Introductory sections help readers get up to speed with the theories of turbulence, combustion, and multiphysics, along with the basics of simulation and modelling. This is followed by thorough treatments of the numerical methods, boundary conditions, and specific modelling approaches for different purposes. Applications in fields including aerospace, biomedical, and chemical engineering are investigated where appropriate. This is the ideal guide for readers interested in direct numerical simulation, or modelling/simulation of turbulence more generally, who need an overview of the methods available and advice on how to select and implement the correct one.

Physical Multiscale Modeling and Numerical Simulation of Electrochemical Devices for Energy Conversion and Storage

Physical Multiscale Modeling and Numerical Simulation of Electrochemical Devices for Energy Conversion and Storage
Author : Alejandro A. Franco,Marie Liesse Doublet,Wolfgang G. Bessler
Publisher : Springer
Release Date : 2015-11-12
Category : Technology & Engineering
Total pages :249
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The aim of this book is to review innovative physical multiscale modeling methods which numerically simulate the structure and properties of electrochemical devices for energy storage and conversion. Written by world-class experts in the field, it revisits concepts, methodologies and approaches connecting ab initio with micro-, meso- and macro-scale modeling of components and cells. It also discusses the major scientific challenges of this field, such as that of lithium-ion batteries. This book demonstrates how fuel cells and batteries can be brought together to take advantage of well-established multi-scale physical modeling methodologies to advance research in this area. This book also highlights promising capabilities of such approaches for inexpensive virtual experimentation. In recent years, electrochemical systems such as polymer electrolyte membrane fuel cells, solid oxide fuel cells, water electrolyzers, lithium-ion batteries and supercapacitors have attracted much attention due to their potential for clean energy conversion and as storage devices. This has resulted in tremendous technological progress, such as the development of new electrolytes and new engineering designs of electrode structures. However, these technologies do not yet possess all the necessary characteristics, especially in terms of cost and durability, to compete within the most attractive markets. Physical multiscale modeling approaches bridge the gap between materials’ atomistic and structural properties and the macroscopic behavior of a device. They play a crucial role in optimizing the materials and operation in real-life conditions, thereby enabling enhanced cell performance and durability at a reduced cost. This book provides a valuable resource for researchers, engineers and students interested in physical modelling, numerical simulation, electrochemistry and theoretical chemistry.

Multiscale Modeling, Simulation and Visualization and Their Potential for Future Aerospace Systems

Multiscale Modeling, Simulation and Visualization and Their Potential for Future Aerospace Systems
Author : Anonim
Publisher : Unknown
Release Date : 2002
Category : Composite materials
Total pages :442
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Numerical Simulation of Aeroacoustics Using the Variational Multiscale Method : Application to the Problem of Human Phonation

Numerical Simulation of Aeroacoustics Using the Variational Multiscale Method : Application to the Problem of Human Phonation
Author : Arnau Pont Ribas
Publisher : Unknown
Release Date : 2018
Category :
Total pages :211
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The solution of the human phonation problem applying computational mechanics is covered by several research branches, such as Computational Fluid Dynamics (CFD), biomechanics or acoustics, among others. In the present thesis, the problem is approached from the Computational Aeroacoustics (C18) point of view and the first main objective consists in developing numerical methods of general application that can take part in the solution of any scenario related to human phonation with a reasonable cost. In this sense, only the compressible Navier-Stokes equations can describe all flow and acoustic scales without any modeling, which is known as Direct Numerical Simulation (DNS), but its computational cost is usually unaffordable. Even in the case of a Large Eddy Simulation (LES), where the small scales are modeled, the cost can still be a handicap due to the complexity of the problem. This drawback gets worse in the low Mach regime due to the large disparity between flow velocity and sound speed, which leads to an ill-conditioning of the system of equations, specially for conservative schemes. At this point, it makes sense to move towards the incompressible flow approximation, bearing in mind the low velocities expected in human phonation problems. Incompressible flows do not yield any acoustics, for which a second problem containing the propagation of the sound sources needs to be modeled and solved. These are the so called hybrid methods, which allow a better conditioning of the problem by segregating flow and acoustic scales. Lighthill's analogy has been taken as starting point for the present work, but its restriction to free-field scenarios has motivated the extension of the method to arbitrary geometries and non-uniform flows. The first development in this direction consists in a splitting of Lighthill's analogy into a quadrupolar and dipolar component, which does not change the original problem but allows assessing the contribution of solid boundaries to the generation of sound. The second step consists in the development of a stabilized Finite Element (FEM) formulation for the Acoustic Perturbation Equations (APE) which account for non-uniform flows and perform a complete filtering of the acoustic scales. The final step assumes the compressible approach but omitting the energy equation and thus considering both flow and acoustic propagation as isentropic. In this case the solver is unified and hence a method for applying compatible boundary conditions for flow and acoustics has been developed. Moreover, the whole numerical framework has been extended to dynamic phonation cases, which require using an Arbitrary Lagrangian Eulerian (ALE) reference. Also, a novel remeshing strategy with conservative interpolation between meshes is presented. In the last chapter a challenging case in human phonation has been chosen for testing the developed computational framework: the fricative phoneme /s/. Unlike vowels, which are voiced sounds defined by a few characteristic frequencies, fricatives cannot be simulated as the propagation of a known analytic solution (glottal pulse) because the sound sources correspond to a wide range of turbulent scales. Therefore, a CFD calculation is mandatory in order to capture all relevant eddies behind the generation of sound. This problem is solved with an LES together with the Variational Multiscale (VMS) stabilization method as turbulence model, which is supplemented with several acoustic formulations when using incompressible flow. The analysis of the results focuses on the numerical representation of turbulence and the acoustic signal at the far-field, which has been compared to experimental recordings. Finally, the role of the upper incisors in the generation of the fricative sound has been evaluated. All simulations have been run with the parallel multiphysics FEM code FEMUSS, based on FORTRAN Object-Oriented-Programming land the OpenMPI parallel library.

Multiscale and Multiresolution Approaches in Turbulence

Multiscale and Multiresolution Approaches in Turbulence
Author : Pierre Sagaut
Publisher : World Scientific
Release Date : 2013
Category : Science
Total pages :448
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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.

Models, Simulation, and Experimental Issues in Structural Mechanics

Models, Simulation, and Experimental Issues in Structural Mechanics
Author : Michel Frémond,Franco Maceri,Giuseppe Vairo
Publisher : Springer
Release Date : 2017-01-21
Category : Science
Total pages :267
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This book offers valuable insights and provides effective tools useful for imagining, creating, and promoting novel and challenging developments in structural mechanics. It addresses a wide range of topics, such as mechanics and geotechnics, vibration and damping, damage and friction, experimental methods, and advanced structural materials. It also discusses analytical, experimental and numerical findings, focusing on theoretical and practical issues and innovations in the field. Collecting some of the latest results from the Lagrange Laboratory, a European scientific research group, mainly consisting of Italian and French engineers, mechanicians and mathematicians, the book presents the most recent example of the long-term scientific cooperation between well-established French and Italian Mechanics, Mathematics and Engineering Schools. It is a valuable resource for postgraduate students, researchers and practitioners dealing with theoretical and practical issues in structural engineering.

Data Analysis for Direct Numerical Simulations of Turbulent Combustion

Data Analysis for Direct Numerical Simulations of Turbulent Combustion
Author : Heinz Pitsch,Antonio Attili
Publisher : Springer Nature
Release Date : 2020-05-28
Category : Mathematics
Total pages :292
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This book presents methodologies for analysing large data sets produced by the direct numerical simulation (DNS) of turbulence and combustion. It describes the development of models that can be used to analyse large eddy simulations, and highlights both the most common techniques and newly emerging ones. The chapters, written by internationally respected experts, invite readers to consider DNS of turbulence and combustion from a formal, data-driven standpoint, rather than one led by experience and intuition. This perspective allows readers to recognise the shortcomings of existing models, with the ultimate goal of quantifying and reducing model-based uncertainty. In addition, recent advances in machine learning and statistical inferences offer new insights on the interpretation of DNS data. The book will especially benefit graduate-level students and researchers in mechanical and aerospace engineering, e.g. those with an interest in general fluid mechanics, applied mathematics, and the environmental and atmospheric sciences.

An Improved Multiscale Model for Dilute Turbulent Gas Particle Flows Based on the Equilibration of Energy Concept

An Improved Multiscale Model for Dilute Turbulent Gas Particle Flows Based on the Equilibration of Energy Concept
Author : Ying Xu
Publisher : Unknown
Release Date : 2004
Category :
Total pages :134
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Many particle-laden flows in engineering applications involve turbulent gas flows. Modeling multiphase turbulent flows is an important research topic with applications in fluidized beds and particle conveying. A predictive multiphase turbulence model can help CFD codes to be more useful for engineering applications, such as the scale-up in the design of circulating fluidized combustor and coal gasifications. It is reasonable to expect that multiphase turbulence models should at least satisfy some basic modeling and performance criteria and give reasonable predictions for the canonical problems in dilute particle-laden turbulent flows. In this research, a comparative assessment of predictions from Simonin and Ahmadi's turbulence models is performed with direct numerical simulation (DNS) for two canonical problems in particle-laden turbulent flows. Based on the comparative assessment, some criteria and the areas for model improvement are identified: (i) model for interphase TKE transfer, especially the time scale of interphase TKE transfer, and (ii) correct prediction of TKE evolution with variation of particle Stokes number. Some deficiencies that are identified in the Simonin and Ahmadi models limit the applicability. A new multiphase turbulence model, the Equilibration of Energy Model (EEM), is proposed in this work. In EEM, a multiscale interaction time scale is proposed to account for the interaction of a particle with a range of eddy sizes. EEM shows good agreement with the DNS results for particle-laden istropic turbulence. For particle-laden homogeneous shear flows, model predictions from EEM can be further improved if the dissipation rate in fluid phase is modeled with more accuracy. This new time scale is incorporated in the interphase TKE transfer terms of the Simonin and Ahmadi models. For canonical problems in particle-laden turbulent flows, this time scale improves the predictions from these two models. Although EEM is a simple model, it has a clear physical interpretation and gives reasonable predictions for two canonical problems in particle-laden turbulent flows. It can be a useful engineering tool for CFD calculations of gas-solid two phase flows.

Multiscale Modeling in Biomechanics and Mechanobiology

Multiscale Modeling in Biomechanics and Mechanobiology
Author : Suvranu De,Wonmuk Hwang,Ellen Kuhl
Publisher : Springer
Release Date : 2014-10-10
Category : Technology & Engineering
Total pages :286
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Presenting a state-of-the-art overview of theoretical and computational models that link characteristic biomechanical phenomena, this book provides guidelines and examples for creating multiscale models in representative systems and organisms. It develops the reader's understanding of and intuition for multiscale phenomena in biomechanics and mechanobiology, and introduces a mathematical framework and computational techniques paramount to creating predictive multiscale models. Biomechanics involves the study of the interactions of physical forces with biological systems at all scales – including molecular, cellular, tissue and organ scales. The emerging field of mechanobiology focuses on the way that cells produce and respond to mechanical forces – bridging the science of mechanics with the disciplines of genetics and molecular biology. Linking disparate spatial and temporal scales using computational techniques is emerging as a key concept in investigating some of the complex problems underlying these disciplines. Providing an invaluable field manual for graduate students and researchers of theoretical and computational modelling in biology, this book is also intended for readers interested in biomedical engineering, applied mechanics and mathematical biology.

Multi-scale Simulation of Composite Materials

Multi-scale Simulation of Composite Materials
Author : Stefan Diebels,Sergej Rjasanow
Publisher : Springer
Release Date : 2019-02-01
Category : Science
Total pages :178
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Due to their high stiffness and strength and their good processing properties short fibre reinforced thermoplastics are well-established construction materials. Up to now, simulation of engineering parts consisting of short fibre reinforced thermoplastics has often been based on macroscopic phenomenological models, but deformations, damage and failure of composite materials strongly depend on their microstructure. The typical modes of failure of short fibre thermoplastics enriched with glass fibres are matrix failure, rupture of fibres and delamination, and pure macroscopic consideration is not sufficient to predict those effects. The typical predictive phenomenological models are complex and only available for very special failures. A quantitative prediction on how failure will change depending on the content and orientation of the fibres is generally not possible, and the direct involvement of the above effects in a numerical simulation requires multi-scale modelling. One the one hand, this makes it possible to take into account the properties of the matrix material and the fibre material, the microstructure of the composite in terms of fibre content, fibre orientation and shape as well as the properties of the interface between fibres and matrix. On the other hand, the multi-scale approach links these local properties to the global behaviour and forms the basis for the dimensioning and design of engineering components. Furthermore, multi-scale numerical simulations are required to allow efficient solution of the models when investigating three-dimensional problems of dimensioning engineering parts. Bringing together mathematical modelling, materials mechanics, numerical methods and experimental engineering, this book provides a unique overview of multi-scale modelling approaches, multi-scale simulations and experimental investigations of short fibre reinforced thermoplastics. The first chapters focus on two principal subjects: the mathematical and mechanical models governing composite properties and damage description. The subsequent chapters present numerical algorithms based on the Finite Element Method and the Boundary Element Method, both of which make explicit use of the composite’s microstructure. Further, the results of the numerical simulations are shown and compared to experimental results. Lastly, the book investigates deformation and failure of composite materials experimentally, explaining the applied methods and presenting the results for different volume fractions of fibres. This book is a valuable resource for applied mathematics, theoretical and experimental mechanical engineers as well as engineers in industry dealing with modelling and simulation of short fibre reinforced composites.

Analysis, Modeling and Simulation of Multiscale Problems

Analysis, Modeling and Simulation of Multiscale Problems
Author : Alexander Mielke
Publisher : Springer Science & Business Media
Release Date : 2006-10-14
Category : Mathematics
Total pages :697
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This book reports recent mathematical developments in the Programme "Analysis, Modeling and Simulation of Multiscale Problems", which started as a German research initiative in 2006. Multiscale problems occur in many fields of science, such as microstructures in materials, sharp-interface models, many-particle systems and motions on different spatial and temporal scales in quantum mechanics or in molecular dynamics. The book presents current mathematical foundations of modeling, and proposes efficient numerical treatment.

From Multiscale Modeling to Meso-Science

From Multiscale Modeling to Meso-Science
Author : Jinghai Li,Wei Ge,Wei Wang,Ning Yang,Xinhua Liu,Limin Wang,Xianfeng He,Xiaowei Wang,Junwu Wang,Mooson Kwauk
Publisher : Springer Science & Business Media
Release Date : 2013-03-22
Category : Technology & Engineering
Total pages :484
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Multiscale modeling is becoming essential for accurate, rapid simulation in science and engineering. This book presents the results of three decades of research on multiscale modeling in process engineering from principles to application, and its generalization for different fields. This book considers the universality of meso-scale phenomena for the first time, and provides insight into the emerging discipline that unifies them, meso-science, as well as new perspectives for virtual process engineering. Multiscale modeling is applied in areas including: multiphase flow and fluid dynamics chemical, biochemical and process engineering mineral processing and metallurgical engineering energy and resources materials science and engineering Jinghai Li is Vice-President of the Chinese Academy of Sciences (CAS), a professor at the Institute of Process Engineering, CAS, and leader of the EMMS (Energy-minimizing multiscale) Group. Wei Ge, Wei Wang, Ning Yang and Junwu Wang are professors at the EMMS Group, part of the Institute of Process Engineering, CAS. Xinhua Liu, Limin Wang, Xianfeng He and Xiaowei Wang are associate professors at the EMMS Group, part of the Institute of Process Engineering, CAS. Mooson Kwauk is an emeritus director of the Institute of Process Engineering, CAS, and is an advisor to the EMMS Group.

Direct Numerical Simulations of Gas–Liquid Multiphase Flows

Direct Numerical Simulations of Gas–Liquid Multiphase Flows
Author : Grétar Tryggvason,Ruben Scardovelli,Stéphane Zaleski
Publisher : Cambridge University Press
Release Date : 2011-03-10
Category : Computers
Total pages :129
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Accurately predicting the behaviour of multiphase flows is a problem of immense industrial and scientific interest. Modern computers can now study the dynamics in great detail and these simulations yield unprecedented insight. This book provides a comprehensive introduction to direct numerical simulations of multiphase flows for researchers and graduate students. After a brief overview of the context and history the authors review the governing equations. A particular emphasis is placed on the 'one-fluid' formulation where a single set of equations is used to describe the entire flow field and interface terms are included as singularity distributions. Several applications are discussed, showing how direct numerical simulations have helped researchers advance both our understanding and our ability to make predictions. The final chapter gives an overview of recent studies of flows with relatively complex physics, such as mass transfer and chemical reactions, solidification and boiling, and includes extensive references to current work.

Numerical Simulations of Coupled Problems in Engineering

Numerical Simulations of Coupled Problems in Engineering
Author : Sergio R. Idelsohn
Publisher : Springer
Release Date : 2014-05-09
Category : Technology & Engineering
Total pages :422
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This book presents and discusses mathematical models, numerical methods and computational techniques used for solving coupled problems in science and engineering. It takes a step forward in the formulation and solution of real-life problems with a multidisciplinary vision, accounting for all of the complex couplings involved in the physical description. Simulation of multifaceted physics problems is a common task in applied research and industry. Often a suitable solver is built by connecting together several single-aspect solvers into a network. In this book, research in various fields was selected for consideration: adaptive methodology for multi-physics solvers, multi-physics phenomena and coupled-field solutions, leading to computationally intensive structural analysis. The strategies which are used to keep these problems computationally affordable are of special interest, and make this an essential book.

Advances in Computational Mechanics

Advances in Computational Mechanics
Author : Grant P. Steven,Qing Li,Zhong Pu Zhang
Publisher : Trans Tech Publications Ltd
Release Date : 2014-05-21
Category : Technology & Engineering
Total pages :890
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Collection of selected, peer reviewed papers from the Australasian Conference of Computational Mechanics 2013 (ACCM 2013), October 3-4, 2013, Sydney, Australia. The 139 papers are grouped as follows: Chapter 1: Advanced Materials and Multiscale Modelling, Chapter 2: Computational Fluid Dynamics and Thermofluids, Chapter 3: Aerospace and Vehicle Engineering, Chapter 4: Biomechanics, Biomimetics and Biomedical Engineering, Chapter 5: Geomechanics and Geotechnics, Chapter 6: Structural and Solid Mechanics, Chapter 7: Vibration and Dynamics, Chapter 8: Fracture and Damage, Chapter 9: Impact and Explosive Modelling, Chapter 10: Structural and Topology Optimization