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About 10,000 papers for “Large eddy simulation”

LARGE EDDY SIMULATION

Chin‐Hoh Moeng, Peter P. Sullivan · Encyclopedia of Atmospheric Sciences · 2003

Cited by 31

Large Eddy Simulation

Joel H. Ferziger · Oxford University Press eBooks · 1996

Over a decade ago, the author (Ferziger, 1983) wrote a review of the then state-of-the-art in direct numerical simulation (DNS) and large eddy simulation (LES). Shortly thereafter, a second review was written by Rogallo and Moin (1984). In those relatively early days of turbulent flow simulation, it was possible to write comprehensive reviews of what had been accomplished. Since then, the widespread availability of supercomputers has led to an explosion in this field so, although the subject is undoubtedly overdue for another review, it is not clear that the task can be accomplished in anything less than a monograph. The author therefore apologizes in advance for omissions (there must be many) and for any bias toward the accomplishments of people on the west coast of North America. In the earlier review, the author listed six approaches to the prediction of turbulent flow behavior. The list included: correlations, integral methods, single-point Reynolds-averaged closures, two-point closures, large eddy simulation and direct numerical simulation. Even then the distinction between these methods was not always clear; if anything, it is less clear today. It was possible in the earlier review to give a relatively complete overview of what had been accomplished with simulation methods. Since then, simulation techniques have been applied to an ever expanding range of flows so a thorough review of simulation results is no longer possible in the space available here. Simulation techniques have become well established as a means of studying turbulent flows and the results of simulations are best presented in combination with experimental data for the same flow. There is also a danger that the success of simulation methods will lead to attempts to apply them too soon to flows which the models and techniques are not ready to handle. To some extent, this is already happening. Direct numerical simulation (DNS) is a method in which all of the scales of motion of a turbulent flow are computed. A DNS must include everything from the large energy-containing or integral scales to the dissipative scales; the latter is usually taken to be the viscous or Kolmogoroff scales.

Cited by 297

Temporal Large-Eddy Simulation

Thomas, B. C., Pruett, C. D. · NASA Technical Reports Server (NASA)

In 1999, Stolz and Adams unveiled a subgrid-scale model for LES based upon approximately inverting (defiltering) the spatial grid-filter operator and termed .the approximate deconvolution model (ADM). Subsequently, the utility and accuracy of the ADM were demonstrated in a posteriori analyses of flows as diverse as incompressible plane-channel flow and supersonic compression-ramp flow. In a prelude to the current paper, a parameterized temporal ADM (TADM) was developed and demonstrated in both a priori and a posteriori analyses for forced, viscous Burger's flow. The development of a time-filtered variant of the ADM was motivated-primarily by the desire for a unifying theoretical and computational context to encompass direct numerical simulation (DNS), large-eddy simulation (LES), and Reynolds averaged Navier-Stokes simulation (RANS). The resultant methodology was termed temporal LES (TLES). To permit exploration of the parameter space, however, previous analyses of the TADM were restricted to Burger's flow, and it has remained to demonstrate the TADM and TLES methodology for three-dimensional flow. For several reasons, plane-channel flow presents an ideal test case for the TADM. Among these reasons, channel flow is anisotropic, yet it lends itself to highly efficient and accurate spectral numerical methods. Moreover, channel-flow has been investigated extensively by DNS, and a highly accurate data base of Moser et.al. exists. In the present paper, we develop a fully anisotropic TADM model and demonstrate its utility in simulating incompressible plane-channel flow at nominal values of Re(sub tau) = 180 and Re(sub tau) = 590 by the TLES method. The TADM model is shown to perform nearly as well as the ADM at equivalent resolution, thereby establishing TLES as a viable alternative to LES. Moreover, as the current model is suboptimal is some respects, there is considerable room to improve TLES.

Cited by 0Open access

Large eddy simulation applications

Guillaume Dufour, Nicolas Gourdain, Florent Duchaine et al. · Open Archive Toulouse Archive Ouverte (University of Toulouse) · 2009

The objective of the present lecture is to provide an overview of what can be achieved today using state-of-the-art Large Eddy Simulations for turbomachinery components, emphasizing the gain in accuracy and the cost of the method. First, a review of the published literature is performed, highlighting notable achievements in terms of turbomachinery applications with LES. In the second part, two applications of LES in turbomachinery are presented. The first application is a high-pressure turbine stator, the VKI Turmunsflat case, experimentally studied by Sieverding et al. [128]. Simulations with the RANS, URANS and LES methods are compared, clearly illustrating the fundamental differences between the three approaches. The computational cost of the methods is assessed, and compared against the benefits in terms of physical accuracy. The second test case is a highly-loaded high-pressure turbine blade cascade studied within a Conjugate Heat Transfer (CHT) framework. This multi-physics case illustrates the coupling between a LES flow solver and a solid heat-transfer code. Comparisons are made to assess the relative gains obtained with the LES approach (as compared to a RANS simulation) and due to the coupling with the heat-transfer code (as compared to adiabatic simulations).

Cited by 7

Implicit Large Eddy Simulation

Fernando F. Grinstein, L.G. Margolin, William J. Rider · Cambridge University Press eBooks · 2007

The numerical simulation of turbulent flows is a subject of great practical importance to scientists and engineers. The difficulty in achieving predictive simulations is perhaps best illustrated by the wide range of approaches that have been developed and are still being used by the turbulence modeling community. In this book the authors describe one of these approaches, Implicit Large Eddy Simulation (ILES). ILES is a relatively new approach that combines generality and computational efficiency with documented success in many areas of complex fluid flow. This book synthesizes the theoretical basis of the ILES methodology and reviews its accomplishments. ILES pioneers and lead researchers combine here their experience to present a comprehensive description of the methodology. This book should be of fundamental interest to graduate students, basic research scientists, as well as professionals involved in the design and analysis of complex turbulent flows.

Cited by 754

Discrete large eddy simulation

Liyuan Tao, Κ. R. Rajagopal, G.Q. Chen · Communications in Nonlinear Science and Numerical Simulation · 2001

Cited by 4

LES Large Eddy Simulation

Martin Olausson, Lars-erik Eriksson, R Radial Coordinate et al. · 2016

The interaction between rotor wake turbulence and stators is a major source of fan broadband noise. This paper presents a method on how to obtain the low to medium frequencies using a hybrid RANS/LES method. Three stator vanes are discretized and the mean rotor wake is specified at the inlet. Synthetic fluctuations are also added to the inlet profile to trigger the flow into turbulent mode. Chorochronic periodic boundary conditions combined with temporally damped buffer zones (chorochronic buffer zones) are used to make sure that the deterministic part of the wake interaction is taken care of properly. The combination of chorochronic periodicity and buffer zones in the area close to the pitch-wise boundaries efficiently filters the flow field from turbulence generated stochastic fluctuations. The center blade in the domain is relatively unaffected by the filtering effect and the unsteady pressure field, deterministic and turbulence generated, can be used as a source for both tone and broadband noise. The paper also include a comparison between the proposed method and a simulation with modified blade count and standard periodic boundaries. The tone noise will change when the number of blades is modified but the aim is to see whether this has a significant effect on broadband noise.

Cited by 0

Applied large eddy simulation

Paul G. Tucker, Sylvain Lardeau · Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences · 2009

Large eddy simulation (LES) is now seen more and more as a viable alternative to current industrial practice, usually based on problem-specific Reynolds-averaged Navier-Stokes (RANS) methods. Access to detailed flow physics is attractive to industry, especially in an environment in which computer modelling is bound to play an ever increasing role. However, the improvement in accuracy and flow detail has substantial cost. This has so far prevented wider industrial use of LES. The purpose of the applied LES discussion meeting was to address questions regarding what is achievable and what is not, given the current technology and knowledge, for an industrial practitioner who is interested in using LES. The use of LES was explored in an application-centred context between diverse fields. The general flow-governing equation form was explored along with various LES models. The errors occurring in LES were analysed. Also, the hybridization of RANS and LES was considered. The importance of modelling relative to boundary conditions, problem definition and other more mundane aspects were examined. It was to an extent concluded that for LES to make most rapid industrial impact, pragmatic hybrid use of LES, implicit LES and RANS elements will probably be needed. Added to this further, highly industrial sector model parametrizations will be required with clear thought on the key target design parameter(s). The combination of good numerical modelling expertise, a sound understanding of turbulence, along with artistry, pragmatism and the use of recent developments in computer science should dramatically add impetus to the industrial uptake of LES. In the light of the numerous technical challenges that remain it appears that for some time to come LES will have echoes of the high levels of technical knowledge required for safe use of RANS but with much greater fidelity.

Cited by 18

Effects of Eddy . . . IN LARGE EDDY SIMULATION

Guowei He, R. Rubinstein, Lian-ping Wang · 2001

Subgrid-scale (SGS) models for large eddy simulation (LES) have generally been evaluated by their ability to predict single-time statistics of turbulent ows such as kinetic energy and Reynolds stresses. Recent applications of large eddy simulation to the evaluation of sound sources in turbulent ows, a problem in which time correlations determine the frequency distribution of acoustic radiation, suggest that subgrid models should also be evaluated by their ability to predict time correlations in turbulent ows. This paper compares the two-point, two-time Eulerian velocity correlation evaluated from direct numerical simulation (DNS) with that evaluated from LES, using a spectral eddy viscosity, for isotropic homogeneous turbulence. It is found that the LES fields are too coherent, in the sense that their time correlations decay more slowly than the corresponding time correlations in the DNS fields. This observation is confirmed by theoretical estimates of time correlations using the Taylor expansion technique. The reason for the slower decay is that the eddy viscosity does not include the random backscatter, which decorrelates fluid motion at large scales. An effective eddy viscosity associated with time correlations is formulated, to which the eddy viscosity associated with energy transfer is a leading order approximation.

Cited by 0

Large-Eddy Simulation of Ramjets

Anthony Roux, GICQUEL, Laurent, POINSOT, Thierry · theses.fr (ABES) · 2009

La conception d'un statoréacteur bénificie aujourd'hui des progrès divers des outils numériques permettant par la même occasion d'alléger les différentes étapes préliminaires de tests en géométrie réelle nécessaires au développement de telle configuration. L'objectif de cette thèse est de développer une méthodologie s'appuyant sur la Simulation aux Grandes Echelles (SGE) afin de contribuer à la validation de ce nouvel outil numérique pour la simulation de statoréacteur et ainsi de contribuer à la compréhension des phénomènes mis en jeu dans ces chambres de combustion. L'outil numérique est tout d'abord adapté pour la simulation des écoulements réactifs fortement turbulents avec un accent mis sur la gestion des chocs avec des schémas centrés et la discrétisation de la convection pour la simulation Eulérienne de la phase dispersée. La configuration cible est le "Statoréacteur de Recherche'' étudié expérimentalement par l'ONERA. Sa simulation est réalisée de manière graduelle. Tout d'abord, il est montré que la simulation de la totalité de la configuration, y compris les diffuseurs d'entrée où se positionne un réseau de choc, est essentielle afin de considérer une géométrie acoustiquement close pour reproduire correctement les modes d'oscillation du statoréacteur. La pertinence du schéma cinétique est aussi étudiée et il est montré l'importance de bien reproduire l'évolution de la vitesse de flamme adiabatique pour une plage de richesse grande, en raison du régime de combustion partiellement prémélangé. Finalement, trois cas à richesse différente sont simulés et un excellent accord est trouvé avec l'expérience. La phénoménologie et les mécanismes pilotant la combustion sont alors étudiés pour ces trois cas.

Cited by 0Open access

Large-Eddy Simulation for Acoustics

Claus Wagner, Claus Wagner, Thomas Hüttl et al. · Cambridge University Press eBooks · 2007

Noise pollution around airports, trains, and industries increasingly attracts environmental concern and regulation. Designers and researchers have intensified the use of large-eddy simulation (LES) for noise reduced industrial design and acoustical research. This 2007 book, written by 30 experts, presents the theoretical background of acoustics and of LES, followed by details about numerical methods, e.g. discretization schemes, boundary conditions, coupling aspects. Industrially relevant, hybrid RANS/LES techniques for acoustic source predictions are presented in detail. Many applications are featured ranging from simple geometries for mixing layers and jet flows to complex wing and car geometries. Selected applications include scientific investigations at industrial and university research institutions.

Cited by 226

Large eddy simulation in cleanrooms

Hong Fan · Kongqi donglixue xuebao · 2001

By using the technique of turbulent large eddy simulation(LES)and finite element method(FEM)of computational fluid dynamics(CFD),the three dimensional flow fields in vector flow cleanroom and in cleanroom with full ceiling air supply and lateral air return at the bottom of two side walls under empty state and staic state condition were predicted.The partly expanded Taylor Galerkin discretization scheme cooperated with implicit stream upwind diffusion effect was used to deduce the finite element formulation of basic equations through Gauss filtering.The subgrid model of vortex viscosity was adopted in the numerical simulation.As the results of the calculation agree well with the available experimental data,the method of LES was proved to be more accurate to provide the size and location of large eddies in cleanrooms than the standard K e two equations model.

Cited by 0

Large Eddy Simulation turbulenter Strömungen

Jochen Fröhlich · Teubner eBooks · 2006

Die Large Eddy Simulation (LES) ist eine Methode zur Modellierung und Berechnung turbulenter Strömungen. Insbesondere für den praxisrelevanten Fall hoher Reynoldszahlen besitzt sie Vorteile gegenüber anderen Verfahren und findet in den letzten Jahren sehr schnell Verbreitung. Das Buch motiviert den Ansatz auf der Basis physikalischer Grundlagen. Alle Modelltypen, die in derartigen Simulationen auftreten, werden detailliert erläutert und vergleichend diskutiert. Anhand verschiedener Anwendungsbeispiele werden typische Resultate diskutiert und unterschiedliche Techniken zur Auswertung der gewonnenen Daten vorgestellt.

Cited by 11