Numerical Simulation Of Turbulent Flows And Noise Generation
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Numerical Simulation Of Turbulent Flows And Noise Generation
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Author : Christophe Brun
language : en
Publisher: Springer Science & Business Media
Release Date : 2009-03-07
Numerical Simulation Of Turbulent Flows And Noise Generation written by Christophe Brun and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009-03-07 with Technology & Engineering categories.
Large Eddy Simulation (LES) is a high-fidelity approach to the numerical simulation of turbulent flows. Recent developments have shown LES to be able to predict aerodynamic noise generation and propagation as well as the turbulent flow, by means of either a hybrid or a direct approach. This book is based on the results of two French/German research groups working on LES simulations in complex geometries and noise generation in turbulent flows. The results provide insights into modern prediction approaches for turbulent flows and noise generation mechanisms as well as their use for novel noise reduction concepts.
Numerical Simulation Of Acoustic Propagation In A Turbulent Channel Flow With An Acoustic Liner
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Author : Robin Sebastian
language : en
Publisher:
Release Date : 2018
Numerical Simulation Of Acoustic Propagation In A Turbulent Channel Flow With An Acoustic Liner written by Robin Sebastian and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
Acoustic liners are a key technology in aeronautics for the passive reduction of the noise generated by aircraft engines. They are employed in a complex flow scenario in which the acoustic waves, the turbulent flow, and the acoustic liner are interacting.During this thesis, in a context of high performance computing, a compressible Navier-Stokes solver has been developed to perform implicit large eddy simulations of a model problem of this interaction: a turbulent plane channel flow with one wall modeled as an impedance condition.As a preliminary step the wall-turbulence in rigid channel flows and associated large-scale motions are investigated. A straightforward algorithm to detect these flow features is developed and the effect of compressibility on the flow structures and their contribution to the drag are studied. Then, the interaction between the acoustic liner and turbulent flow is investigated assuming periodicity in the streamwise direction. It is shown that low resistance and low resonance frequency tend to trigger flow instability, which modifies the conventional wall-turbulence and also results in drag increase.Finally, the simulation of a spatial channel flow was addressed. In this case no periodicity is assumed and an acoustic wave can be injected at the inlet of the domain. The effect of turbulence on sound attenuation is studied without liner, before a liner is introduced on a part of the channel bottom wall. In this more realistic case, it is confirmed that low resistance acoustic liners trigger an instability at the leading edge of the liner, resulting in drag increase and excess noise generation.
Turbulence And Interactions
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Author : Michel Deville
language : en
Publisher: Springer
Release Date : 2014-10-15
Turbulence And Interactions written by Michel Deville and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-10-15 with Technology & Engineering categories.
Keynote Lectures.- Some Characteristics of Non-Reacting and Reacting Low Swirl Number Jets.- Inner-Outer Interactions in Wall-Bounded Turbulence.- Turbulence Interaction with Atmospheric Physical Processes.- LES of Pulsating Turbulent Flows over Smooth and Wavy Boundaries.- Numerical Study of Turbulence-Wave Interaction.- High Reynolds Number Wall-Bounded Turbulence and a Proposal for a New Eddy-Based Model.- Regular Papers.- PANS Methodology Applied to Elliptic-Relaxation Based Eddy Viscosity Transport Model.- PIV Study of Turbulent Flow in Porous Media.- A Model for Dissipation: Cascade SDE with Markov Regime-Switching and Dirichlet Prior.- Wavelet Analysis of the Turbulent LES Data of the Lid-Driven Cavity Flow.- A Two-Phase LES Compressible Model for Plasma-Liquid Jet Interaction.- Simulation of a Fluidized Bed Using a Hybrid Eulerian-Lagrangian Method for Particle Tracking.- Wavelet-Adapted Sub-grid Scale Models for LES.- Effect of Particle-Particle Collisions on the Spatial Distribution of Inertial Particles Suspended in Homogeneous Isotropic Turbulent Flows.- Effect of Near-Wall Componental Modification of Turbulence on Its Statistical Properties.- Large-Eddy Simulation of Transonic Buffet over a Supercritical Airfoil.- Large Eddy Simulation of Coherent Structures over Forest Canopy.- Toroidal/Poloidal Modes Dynamics in Anisotropic Turbulence.- Grid Filter Modeling for Large-Eddy Simulation.- Pulsating Flow through Porous Media.- Thermodynamic Fluctuations Behaviour during a Sheared Turbulence/Shock Interaction.- LES and DES Study of Fluid-Particle Dynamics in a Human Mouth-Throat Geometry.- Viscous Drag Reduction with Surface-Embedded Grooves.- Study on the Resolution Requirements for DNS in Turbulent Rayleigh-Bénard Convection.- On the Role of Coherent Structures in a Lid Driven Cavity Flow.- Local versus Nonlocal Processes in Turbulent Flows, Kinematic Coupling and General Stochastic Processes.- Time-Resolved 3D Simulation of an Aircraft Wing with Deployed High-Lift System.- Fluid Mechanics and Heat Transfer in a Channel with Spherical and Oval Dimples.- Investigation of the Flow around a Cylinder Plate Configuration with Respect to Aerodynamic Noise Generation Mechanisms.- LES of the Flow around Ahmed Body with Active Flow Control.- Enhanced Bubble Migration in Turbulent Channel Flow by an Acceleration-Dependent Drag Coefficient.- Experimental and Numerical Study of Unsteadiness in Boundary Layer / Shock Wave Interaction.- Measurement of Particle Accelerations with the Laser Doppler Technique.- A Novel Numerical Method for Turbulent, Two-Phase Flow.- Modeling of High Reynolds Number Flows with Solid Body Rotation or Magnetic Fields.- Direct Numerical Simulation of Buoyancy Driven Turbulence inside a Cubic Cavity.- Numerical Simulations of a Massively Separated Reactive Flow Using a DDES Approach for Turbulence Modelling.- Particle Dispersion in Large-Eddy Simulations: Influence of Reynolds Number and of Subgrid Velocity Deconvolution.- Use of Lagrangian Statistics for the Direct Analysis of the Turbulent Constitutive Equation.- Numerical Simulation of Supersonic Jet Noise with Overset Grid Techniques.- Large Eddy Simulation of Turbulent Jet Flow in Gas Turbine Combustors.- Computations of the Flow around a Wind Turbine: Grid Sensitivity Study and the Influence of Inlet Conditions.- Stochastic Synchronization of the Wall Turbulence.- Large-Eddy Simulations of an Oblique Shock Impinging on a Turbulent Boundary Layer: Effect of the Spanwise Confinement on the Low-Frequency Oscillations.- Parameter-Free Symmetry-Preserving Regularization Modelling of Turbulent Natural Convection Flows.- An a Priori Study for the Modeling of Subgrid Terms in Multiphase Flows.- Computation of Flow in a 3D Diffuser Using a Two-Velocity Field Hybrid RANS/LES.- On the Dynamics of High Reynolds Number Turbulent Axisymmetric and Plane Separating/Reattaching Flows.- Numerical Simulation and Statistical Modeling of Inertial Droplet Coalescence
A Parallel Finite Volume Algorithm For Large Eddy Simulation Of Turbulent Flows
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Author : Trong T. Bui
language : en
Publisher:
Release Date : 1998
A Parallel Finite Volume Algorithm For Large Eddy Simulation Of Turbulent Flows written by Trong T. Bui and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with Parallel computers categories.
Non Equilibrium Wall Bounded Turbulence And Associated Noise Generation
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Author : Saurabh Pargal
language : en
Publisher:
Release Date : 2023
Non Equilibrium Wall Bounded Turbulence And Associated Noise Generation written by Saurabh Pargal and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with Electronic dissertations categories.
The present study investigates the response of turbulence in a non-equilibrium flows such as transient periodic channel flows and spatially developing boundary layers subjected to pressure gradients. Such a fundamental study is important to understand noise generation in complex wall-bounded turbulent flows. First, to understand the flow dynamics in transient accelerating flows, direct numerical simulations (DNS) of periodic channel flows responding to an impulse acceleration are carried out. The turbulent flow undergoes reverse transition toward a quasi-laminar state, followed by a retransition phase to the new equilibrium state. To reduced simulation cost, the minimal-span methodology is applied and evaluated for simulations of transient flows.Next, to study non-equilibrium boundary layer flows in the presence of convex wall curvature, DNS simulations over an airfoil (suction side) and a flat plate are compared. Both cases are characterized by matching adverse pressure gradient (APG) along the streamwise direction. For the airfoil boundary layer, existing DNS data obtained by Wu et al. (2019) of flow around a controlled-diffusion (CD) airfoil is used. For the flat-plate boundary layer, a DNS simulation is carried out, with prescribed pressure gradient distribution that matches that of the airfoil case. Comparison between the two cases shows how wall curvature affects turbulence in an APG boundary layer. Overall, similar boundary layer development in both cases indicates that a flat-plate boundary layer can serve as a low-cost surrogate of an airfoil boundary layer.Lastly, various existing analytical models are evaluated on their predictions of wall pressure fluctuations, which are essential for fan noise prediction. Limitations of the existing models are evaluated; new parameters that do not involve the ill-defined wall friction in a boundary layer under strong APG are proposed. The primary role of the mean velocity logarithmic layer in affecting the overlap range of the wall pressure spectrum is also demonstrated. A new wall pressure spectrum model is proposed and tested in a wide range of boundary layer flow scenarios. The new wall pressure spectrum model is the first generalized model designed for boundary layer flows with a wide range of pressure gradients and Reynolds numbers.
Numerical Simulations Of Sound Generation From Jet Flows Through Orifices And Lobed Mixers
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Author : Kaveh Habibi
language : en
Publisher:
Release Date : 2019
Numerical Simulations Of Sound Generation From Jet Flows Through Orifices And Lobed Mixers written by Kaveh Habibi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
"The design of modern aircraft turbofan engines with low noise emissions requires a thorough understanding of noise generation and absorption phenomena in turbulent mixing jets as well as passive noise reduction devices, e.g. lobed mixers or acoustic liners. At the design stage, such understanding should be provided by reliable and accurate prediction tools to avoid prohibitively expensive experiments. Common acoustic prediction tools are either based on semi-empirical models limited to specific applications, or high-order computational fluid dynamics (CFD) codes, involving prohibitive costs for complex problems. The present study investigates the application and validation of a relatively novel approach in Computational Aeroacoustics (CAA) in which the unsteady near-field flow that contains important noise sources is simulated using a three-dimensional Lattice Boltzmann Method (LBM). The far-field sound pressure is predicted using the Ffwocs Williams-Hawkings (FW-H) surface integral method. The effects of turbulence modelling, Reynolds number, Mach number and non-isothermal boundary conditions were tested for canonical jet noise problems. A commercial code, PowerFLOW, based on the Lattice Boltzmann kernel was utilized for the simulations. In the first part of this study, turbulent jet simulations were performed for various configurations including a circular pipe, the SMC000 single-stream nozzle, and internal mixing nozzles with various types of forced mixers. Mean flow and turbulence statistics were obtained as well as sound pressure levels in the far-field. Predictions were compared with experimental data at similar operating conditions for verification. In most cases in which direct comparison were made with experimental data, 1/3 octave band spectral levels were found in good agreement with measured values up to Strouhal number (St) of ~3.0-4.0, also the overall sound pressure levels from simulation were mostly within ~1.0 dB range of measured sound levels. In all case studies, the actual nozzle including various mixer configurations was included in the computational domain in order to achieve realistic flow conditions. In some cases, inflow conditions needed to be imposed using forcing functions in order to mimic experimental conditions and induce enough perturbation for jet transition to turbulence. Both regular and high-order D3Q19 LBM schemes were tested in this study. The former method was restricted to a relatively low Mach numbers up to 0.5, where the latter can technically simulate the flow-field within the higher subsonic range through high-order terms in the discretized momentum equations. In another parallel study, the problem of sound absorption by turbulent jets was studied using a similar Lattice Boltzmann technique. The sound and turbulent flow inside a standing wave tube terminated by a circular orifice in presence of a mean flow was simulated. The computational domain comprised a standard virtual impedance tube apparatus in which sound waves were produced by periodic pressure imposed at one end. A turbulent jet was formed at the discharge of a circular orifice plate by the steady flow inside the tube. The acoustic impedance and sound absorption coefficient of the orifice plate were calculated from a wave decomposition of the sound field upstream of the orifice. Simulations were carried out for different excitation frequencies, amplitudes and orifice Mach numbers. Results and trends were in quantitative agreement with available analytical solution and experimental data. Altogether, the work documented here supports the accuracy and validity of the LBM for detailed flow simulations of complex turbulent jets. This method offers some advantages over Navier-Stokes based simulations for internal and external flows"--
Numerical Simulation Of Turbulent Flows
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Author : Douglas G. Fox
language : en
Publisher:
Release Date : 1971
Numerical Simulation Of Turbulent Flows written by Douglas G. Fox and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1971 with categories.
Advanced Turbulent Flow Computations
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Author : Roger Peyret
language : en
Publisher: Springer
Release Date : 2014-05-04
Advanced Turbulent Flow Computations written by Roger Peyret and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-05-04 with Science categories.
This book collects the lecture notes concerning the IUTAM School on Advanced Turbulent Flow Computations held at CISM in Udine September 7–11, 1998. The course was intended for scientists, engineers and post-graduate students interested in the application of advanced numerical techniques for simulating turbulent flows. The topic comprises two closely connected main subjects: modelling and computation, mesh pionts necessary to simulate complex turbulent flow.
Multiscale And Multiresolution Approaches In Turbulence
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Author : Pierre Sagaut
language : en
Publisher: Imperial College Press
Release Date : 2006
Multiscale And Multiresolution Approaches In Turbulence written by Pierre Sagaut and has been published by Imperial College Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Science categories.
This unique book gives a general unified presentation of the use of the multiscale/multiresolution approaches in the field of turbulence. The coverage ranges from statistical models developed for engineering purposes to multiresolution algorithms for the direct computation of turbulence. It provides the only available up-to-date reviews dealing with the latest and most advanced turbulence models (including LES, VLES, hybrid RANS/LES, DES) and numerical strategies. The book aims at providing the reader with a comprehensive description of modern strategies for turbulent flow simulation, ranging from turbulence modeling to the most advanced multilevel numerical methods. Sample Chapter(s). Chapter 1: A Brief Introduction to Turbulence (4,125 KB). Contents: A Brief Introduction to Turbulence; Turbulence Simulation and Scale Separation; Statistical Multiscale Modeling; Multiscale Subgrid Models: Self-Adaptivity; Structural Multiscale Subgrid Models: Small Scale Estimations; Unsteady Turbulence Simulation on Self-Adaptive Grids; Global Hybrid RANS/LES Methods; Zonal RANS/LES Methods. Readership: Researchers and engineers in academia and industry in aerospace, automotive and other aerodynamics-oriented fields; masters-level students in fluid mechanics, computational fluid dynamics and applied mathematics.
Simulation Of Turbulent Flows With And Without Combustion With Emphasis On The Impact Of Coherent Structures On The Turbulent Mixing
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Author : Cunha Galeazzo, Flavio Cesar
language : en
Publisher: KIT Scientific Publishing
Release Date : 2016-10-14
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 has been published by KIT Scientific Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-10-14 with Chemical engineering categories.
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.