Download or read book High fidelity Simulations and Modeling of Compressible Reacting Flows written by Amirreza Saghafian and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Scramjets are air-breathing propulsion devices and have long been recognized as suitable for hypersonic propulsion. Because of the high speed in scramjet combustors, the flow has a very short residence time before leaving the engine, during which air and fuel must mix on a molecular level and chemical reactions have to be completed. Although some ground and flight experiments have successfully demonstrated the feasibility of supersonic combustion, experimental testing requires a large investment and presents numerous difficulties. Computational tools are thus a key element toward the development of an efficient, high-performance scramjet engine, and because mixing and heat release are at the heart of a scramjet operation, the development and use of accurate combustion models for supersonic combustion are critical. The open questions in supersonic combustion span the spectrum from scientific pursuit, e.g., shock/flame interactions, to engineering applications like prediction of unstart phenomena in scramjets. In this study, direct numerical simulations (DNS) of a compressible reacting mixing layer with finite rate chemistry are performed. The DNS databases are used to explore the physics of supersonic combustion. An efficient combustion model based on the flamelet/progress variable is then introduced. In this approach, only two or three additional scalar transport equations need to be solved, independently of the complexity of the reaction mechanism. The proposed combustion model is validated using DNS databases. Finally, the compressible flamelet/progress variable model is applied to the case of an under-expanded hydrogen jet in a supersonic cross-flow and HIFiRE scramjet.

Download or read book Development of high fidelity numerical methods for turbulent flows simulation written by Francesco Capuano and published by Youcanprint. This book was released on 2019-12-27 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: La tesi di dottorato è incentrata sullo sviluppo di strumenti e metodologie avanzate per la simulazione numerica di flussi turbolenti con tecniche Large-Eddy Simulation (LES) e Direct Numerical Simulation (DNS). In particolare, si propone una metodologia di avanzamento temporale innovativa di tipo Runge-Kutta(RK) capace di riprodurre le prestazioni di robustezza dei metodi skew-symmetric classici con maggiore efficienza computazionale. La rigorosa trattazione teorica sviluppata nel lavoro ha permesso di ricavare nuovi schemi RK con un determinato ordine di accuratezza sulla soluzione e sulla conservazione di energia discreta. La tecnica ha mostrato di essere più efficiente degli schemi classici, fornendo, a parità di risultati, tempi di calcolo inferiori fino al 50%.

Download or read book Modeling and Simulation of Reactive Flows written by A.L. De Bortoli and published by Elsevier. This book was released on 2015-07-17 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modelling and Simulation of Reactive Flows presents information on modeling and how to numerically solve reactive flows. The book offers a distinctive approach that combines diffusion flames and geochemical flow problems, providing users with a comprehensive resource that bridges the gap for scientists, engineers, and the industry. Specifically, the book looks at the basic concepts related to reaction rates, chemical kinetics, and the development of reduced kinetic mechanisms. It considers the most common methods used in practical situations, along with equations for reactive flows, and various techniques-including flamelet, ILDM, and Redim-for jet flames and plumes, with solutions for both. In addition, the book includes techniques to accelerate the convergence of numerical simulation, and a discussion on the analysis of uncertainties with numerical results, making this a useful reference for anyone who is interested in both combustion in free flow and in porous media. Helps readers learn how to apply applications of numerical methods to simulate geochemical kinetics Presents methods on how to transform the transport equations in several coordinate systems Includes discussions of the basic concepts related to reaction rates, chemical kinetics, and the development of reduced kinetic mechanisms, including the most common methods used in practical situations Offers a distinctive approach that combines diffusion flames and geochemical flow problems

Download or read book Towards High performance Discontinuous Galerkin Simulations of Reacting Flows Using Legion written by Kihiro Bando and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-fidelity scale-resolving computational fluid dynamics (CFD) simulations may provide a path towards predictive capabilities for many engineering-relevant applications, in particular those involving the interaction between multiple physics such as turbulent multi-component reacting flows. However, their routine use is hindered by their cost. The throughput of the fastest supercomputers is fortunately still increasing but this comes at the cost of specialized devices and hardware heterogeneity. Modern supercomputing thus imposes new requirements onto numerical algorithms and their implementation for leveraging the available compute while significantly complicating the design, development, and maintenance of massively parallel computational physics software. This dissertation focuses on addressing numerical and implementation challenges of CFD of multi-component reacting flows. It considers high-order discontinuous Galerkin (DG) discretization methods as a way towards a more efficient use of modern compute architectures for performing high-fidelity simulations of configurations involving complex geometries. Both the high accuracy requirement and the ability to accommodate unstructured meshes are key motivations for investigating this class of numerical schemes. The entire content of this manuscript is based on DG-Legion, a novel unstructured DG CFD solver for the compressible Navier-Stokes equations written on top of the Legion system for targeting distributed heterogeneous architectures. The main challenge related to the computer science aspect was to scale the code on GPU supercomputers. An explicit ghost formulation is proposed which results in performance competitive with state-of-the-art solvers based on the message-passing interface (MPI) system while the application code remains free of explicit communication and synchronization, i.e. it has sequential semantics. The contribution related to the numerics addresses two important questions. First, the issue of spurious pressure oscillations generated by fully-conservative schemes for thermally perfect mixtures is analyzed in detail. A generic framework is developed in order to generate systematic variations of the baseline scheme with improved properties. When applied to the problem at hand, several techniques that were previously proposed independently are recovered as special cases in a rigorous way. Finally, a hybrid strategy for preserving the positivity of DG solutions for the composition-describing scalars is introduced. The method based on the composition of subcell finite volume schemes and linear-scaling limiters leads to an overall positivity-preserving scheme in the inviscid limit, compatible with higher-order quadrature rules, and better preserving the subcell resolution compared to only using rescaling techniques.

Download or read book Simulation of Turbulent Flows with and without Combustion with Emphasis on the Impact of Coherent Structures on the Turbulent Mixing written by Cunha Galeazzo, Flavio Cesar and published by KIT Scientific Publishing. This book was released on 2016-10-14 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Computational Models for Turbulent Reacting Flows written by Rodney O. Fox and published by Cambridge University Press. This book was released on 2003-10-30 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Table of contents

Download or read book Advanced Models for Turbulent Spray and Combustion Simulations written by Abolfazl Irannejad and published by LAP Lambert Academic Publishing. This book was released on 2015-08-27 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: A high-fidelity two-phase large eddy simulation (LES)/filtered mass density function (FMDF) model is developed and used for detailed simulations of turbulent spray breakup, evaporation and combustion. The spray is simulated with Lagrangian droplet transport, stochastic breakup, wake, collision/coalescence and finite rate heat and mass transfer submodels. The spray/droplet model is used together with a compressible LES gas flow model for numerical simulations of high pressure liquid jets sprayed into a high temperature and pressure gas chamber. The developed spray LES model is coupled with the two-phase FMDF model for simulation of high speed spray combustion. The FMDF is a subgrid-scale probability density function (PDF) model for LES of turbulent reacting fows and is obtained by the solution of a set of stochastic differential equations by a Lagrangian Monte Carlo method. Complex skeletal kinetics models are used for the chemical reaction together with in situ adaptive tabulation (ISAT) and chemistry workload balancing for efficient parallel computations.

Download or read book 29th International Symposium on Shock Waves 1 written by Riccardo Bonazza and published by Springer. This book was released on 2015-07-09 with total page 832 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings present the results of the 29th International Symposium on Shock Waves (ISSW29) which was held in Madison, Wisconsin, U.S.A., from July 14 to July 19, 2013. It was organized by the Wisconsin Shock Tube Laboratory, which is part of the College of Engineering of the University of Wisconsin-Madison. The ISSW29 focused on the following areas: Blast Waves, Chemically Reactive Flows, Detonation and Combustion, Facilities, Flow Visualization, Hypersonic Flow, Ignition, Impact and Compaction, Industrial Applications, Magnetohydrodynamics, Medical and Biological Applications, Nozzle Flow, Numerical Methods, Plasmas, Propulsion, Richtmyer-Meshkov Instability, Shock-Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shock Waves in Condensed Matter, Shock Waves in Multiphase Flow, as well as Shock Waves in Rarefield Flow. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 29 and individuals interested in these fields.

Download or read book Non Ideal Compressible Fluid Dynamics for Propulsion and Power written by Francesca di Mare and published by Springer Nature. This book was released on 2020-07-08 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reports on advanced theories and methods aimed at characterizing the dynamics of non-ideal compressible fluids. A special emphasis is given to research fostering the use of non-ideal compressible fluids for propulsion and power engineering. Both numerical and experimental studies, as well as simulations, are described in the book, which is based on selected contributions and keynote lectures presented at the 2nd International Seminar on Non-Ideal Compressible-Fluid Dynamics for Propulsion & Power. Held on October 4-5 in Bochum, Germany, the seminar aimed at fostering collaborations between academics and professionals. The two perspectives have been gathered together in this book, which offers a timely guide to advanced fundamentals, innovative methods and current applications of non-ideal compressible fluids to developing turbomachines, and for propulsion and power generation.

Download or read book Boundary Layer Flows Advances in Experimentation Modelling and Simulation written by Zambri Harun and published by BoD – Books on Demand. This book was released on 2024-07-24 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid mechanics is a branch of physics with important applications in daily life. The calculation of flow drag on automobiles and high-speed trains benefits from theories in fluid mechanics. Moreover, many mechanical-based devices such as fluid pumps contribute to efficiency, and thus, to the modernization of society. This book highlights the experimental and theoretical aspects of wall-bounded flows to provide important information about related theories and applications. Boundary layer flow experimentation, modelling, and simulation must be considered together to obtain accurate calculations of parameters such as velocity profiles, pressure distribution, and turbulence level. This book is organized into three sections on the structure of the boundary layer, drag reduction initiatives using active control, and the verification and applications of flow mechanics. Chapters discuss the boundary layer type of different pressure gradients, Reynolds number, and speeds from 5 m/s to Mach 3. They also present the results of research on the active control technique for drag reduction initiatives to achieve efficient turbulence in high-speed applications, flow meter devices, and turbulence-generated noise mitigation initiatives.

Download or read book Data driven modeling and optimization in fluid dynamics From physics based to machine learning approaches written by Michel Bergmann and published by Frontiers Media SA. This book was released on 2023-01-05 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Simulations of Compressible Diffusive Reactive Flows with Detailed Chemistry Using a High order Hybrid WENO CD Scheme written by Jack L. Ziegler and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Atomization and Sprays written by Nasser Ashgriz and published by Springer Science & Business Media. This book was released on 2011-02-18 with total page 922 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atomization and sprays are used in a wide range of industries: mechanical, chemical, aerospace, and civil engineering; material science and metallurgy; food; pharmaceutical, forestry, environmental protection; medicine; agriculture; meteorology and others. Some specific applications are spray combustion in furnaces, gas turbines and rockets, spray drying and cooling, air conditioning, powdered metallurgy, spray painting and coating, inhalation therapy, and many others. The Handbook of Atomization and Sprays will bring together the fundamental and applied material from all fields into one comprehensive source. Subject areas included in the reference are droplets, theoretical models and numerical simulations, phase Doppler particle analysis, applications, devices and more.

Download or read book Practical Methods for Simulation of Compressible Flow and Structure Interactions written by Nipun Kwatra and published by Stanford University. This book was released on 2011 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a semi-implicit method for simulating inviscid compressible flow and its extensions for strong implicit coupling of compressible flow with Lagrangian solids, and artificial transition of fluid from compressible flow to incompressible flow regime for graphics applications. First we present a novel semi-implicit method for alleviating the stringent CFL condition imposed by the sound speed in simulating inviscid compressible flow with shocks, contacts and rarefactions. The method splits the compressible flow flux into two parts -- an advection part and an acoustic part. The advection part is solved using an explicit scheme, while the acoustic part is solved using an implicit method allowing us to avoid the sound speed imposed CFL restriction. Our method leads to a standard Poisson equation similar to what one would solve for incompressible flow, but has an identity term more similar to a diffusion equation. In the limit as the sound speed goes to infinity, one obtains the Poisson equation for incompressible flow. This implicit pressure solve also lends itself nicely to solve for the pressure and coupling forces at a solid fluid interface. With this pressure solve as the foundation, we then develop a novel method to implicitly two-way couple Eulerian compressible flow to volumetric Lagrangian solids. The method works for both deformable and rigid solids and for arbitrary equations of state. Similar to previous fluid-structure interaction methods, we apply pressure forces to the solid and enforce a velocity boundary condition on the fluid in order to satisfy a no-slip constraint. Unlike previous methods, however, we apply these coupled interactions implicitly by adding the constraint to the pressure system and combining it with any implicit solid forces in order to obtain a strongly coupled system. Because our method handles the fluid-structure interactions implicitly, we avoid introducing any new time step restrictions and obtain stable results even for high density-to-mass ratios, where explicit methods struggle or fail. We exactly conserve momentum and kinetic energy (thermal fluid-structure interactions are not considered) at the fluid-structure interface, and hence naturally handle highly non-linear phenomenon such as shocks, contacts and rarefactions. The implicit pressure solve allows our method to be used for any sound speed efficiently. In particular as the sound speed goes to infinity, we obtain the standard Poisson equation for incompressible flow. This allows our method to work seamlessly and efficiently as the sound speed in the underlying flow field changes. Building on this feature of our method, we next develop a practical approach to integrating shock wave dynamics into traditional smoke simulations. Previous methods for doing this either simplified away the compressible component of the flow and were unable to capture shock fronts or used a prohibitively expensive explicit method that limits the time step of the simulation long after the relevant shock waves and rarefactions have left the domain. Instead, using our semi-implicit formulation allows us to take time steps on the order of fluid velocity. As we handle the acoustic fluid effects implicitly, we can artificially drive the sound speed c of the fluid to infinity without going unstable or driving the time step to zero. This permits the fluid to transition from compressible flow to the far more tractable incompressible flow regime once the interesting compressible flow phenomena (such as shocks) have left the domain of interest, and allows the use of state-of-the-art smoke simulation techniques.

Download or read book Numerical Simulation of Compressible Reactive Flows written by Bing Wang and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical simulation has been widely employed to investigate the compressible flows since it is difficult to carry out the experimental measurements, especially in the reactive flows. The shock-wave capturing scheme will be necessary for resolving the compressible flows, and moreover the careful treatments of chemical reaction should be considered for proceeding numerical simulation stable and fast. Recently, the present authors have tried to establish a high-resolution numerical solver for computing the compressible reactive flows. This chapter presents the numerical procedures acquired in this solver for computing the fluxes using weighted essentially non-oscillatory (WENO) scheme, dealing with chemical stiffness problems, and tracing droplets and their interaction with the compressible fluids. As examples, the Taylor-Green vortex (TGV) problem considering the passive scalar mixing, the spatially developing reactive mixing layer flows taken gas-phase hydrogen, and liquid n-decane as fuel are simulated, respectively. Many important characteristics of flow, flame, and ignition are analyzed under the supersonic condition.

Download or read book Mathematical and Numerical Modeling of Turbulent Reactive Flows Using a Hybrid LES PDF Methodology written by João Marcelo Vedovoto and published by . This book was released on 2011 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work is devoted to the development and implementation of a computational framework to perform numerical simulations of low Mach number turbulent reactive flows. The numerical algorithm designed for solving the transport equations relies on a fully implicit predictor-corrector integration scheme. A physically consistent constraint is retained to ensure that the velocity field is solved correctly, and the numerical solver is extensively verified using the Method of Manufactured Solutions (MMS) in both incompressible and variable-density situations. The final computational model relies on a hybrid Large Eddy Simulation / transported Probability Density Function (LES-PDF) framework. Two different turbulence closures are implemented to represent the residual stresses: the classical and the dynamic Smagorinsky models. The specification of realistic turbulent inflow boundary conditions is also addressed in details, and three distinct methodologies are implemented. The crucial importance of this issue with respect to both inert and reactive high fidelity numerical simulations is unambiguously assessed. The influence of residual sub-grid scale scalar fluctuations on the filtered chemical reaction rate is taken into account within the Lagrangian PDF framework. The corresponding PDF model makes use of a Monte Carlo technique: Stochastic Differential Equations (SDE) equivalent to the Fokker-Planck equations are solved for the progress variable of chemical reactions. With the objective of performing LES of turbulent reactive flows in complex geometries, the use of distributed computing is mandatory, and the retained domain decomposition algorithm displays very satisfactory levels of speed-up and efficiency. Finally, the capabilities of the resulting computational model are illustrated on two distinct experimental test cases: the first is a two-dimensional highly turbulent premixed flame established between two streams of fresh reactants and hot burnt gases which is stabilized in a square cross section channel flow. The second is an unconfined high velocity turbulent jet of premixed reactants stabilized by a large co-flowing stream of burned products.

Download or read book CUDA Fortran for Scientists and Engineers written by Gregory Ruetsch and published by Elsevier. This book was released on 2013-09-11 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt: CUDA Fortran for Scientists and Engineers shows how high-performance application developers can leverage the power of GPUs using Fortran, the familiar language of scientific computing and supercomputer performance benchmarking. The authors presume no prior parallel computing experience, and cover the basics along with best practices for efficient GPU computing using CUDA Fortran. To help you add CUDA Fortran to existing Fortran codes, the book explains how to understand the target GPU architecture, identify computationally intensive parts of the code, and modify the code to manage the data and parallelism and optimize performance. All of this is done in Fortran, without having to rewrite in another language. Each concept is illustrated with actual examples so you can immediately evaluate the performance of your code in comparison. Leverage the power of GPU computing with PGI’s CUDA Fortran compiler Gain insights from members of the CUDA Fortran language development team Includes multi-GPU programming in CUDA Fortran, covering both peer-to-peer and message passing interface (MPI) approaches Includes full source code for all the examples and several case studies Download source code and slides from the book's companion website