Large Eddy Simulation of Turbulent Flow Over an Airfoil Using Both Structured and Unstructured Grids PDF Download
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 48
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Book Description
This report describes the application of Large Eddy Simulations (LES) to turbulent flow over an airfoil. Two different approaches have been used, a second-order finite-difference solver on structured grid and a finite-element solver on unstructured grid. Results are presented for the flow around a NACA 4412 airfoil at maximum lift. The diversity of flow characteristics encountered in this flow include laminar, transitional and turbulent boundary layers, flow separation, unstable free shear layers and a wake. while Reynolds-averaged Navier-Stokes simulations (RANS) have had some success when tuned to flows dominated by one such flow characteristic, this variety of flow features taxes the presently available RANS models and presents an excellent opportunity to validate the utility of the dynamic SGS model for LES. Work has also been conducted on high order methods, both for the unstructured and the structured approach.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 48
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Book Description
This report describes the application of Large Eddy Simulations (LES) to turbulent flow over an airfoil. Two different approaches have been used, a second-order finite-difference solver on structured grid and a finite-element solver on unstructured grid. Results are presented for the flow around a NACA 4412 airfoil at maximum lift. The diversity of flow characteristics encountered in this flow include laminar, transitional and turbulent boundary layers, flow separation, unstable free shear layers and a wake. while Reynolds-averaged Navier-Stokes simulations (RANS) have had some success when tuned to flows dominated by one such flow characteristic, this variety of flow features taxes the presently available RANS models and presents an excellent opportunity to validate the utility of the dynamic SGS model for LES. Work has also been conducted on high order methods, both for the unstructured and the structured approach.
Author: Kenneth E. Jansen
Publisher:
ISBN:
Category : Computational fluid dynamics
Languages : en
Pages : 20
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Book Description
Many flows of aeronautical interest have regions where turbulence has a significant effect. For many of these flows, Reynolds-averaged Navier-Stokes simulation (RANSS) techniques do not give an acceptable description of the flow. In these cases a more detailed simulation of the turbulence is required. One such detailed simulation technique, large-eddy simulation (LES) has matured to the point of application to complex flows. Historically, LES have been carried out with structured grids which suffer from two major difficulties: the extension to higher Reynolds numbers leads to an impractical number of grid points, and most real world flows are rather difficult to represent geometrically with structured grids. Unstructured-grid methods offer a release from both of these constraints. Within this sponsored research significant progress has been made towards the application of the above approach to flows of aeronautical interest.
Author:
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Category :
Languages : en
Pages : 0
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Book Description
The turbulent flow over a NACA 4412 airfoil at angle of incidence corresponding to maximum lift (12 degree) has been computed via large-eddy simulation. Two different numerical approaches, one based on a conventional structured mesh and one with a more economical unstructured mesh, have been employed. Results from both simulations differ considerably from each other and from the available experimental data. Differences are found with respect to occurrence of transition near the suction peak and with respect to the amount of backflow (incipient separation) near the trailing edge. The unstructured mesh code predicts rapid boundary layer growth and separation near the trailing edge, whereas the flow remains attached in the structured mesh simulation. It was concluded that a better matching of the transition mechanism (boundary layer tripping) which was employed in the experiments is paramount for an accurate simulation of this flow and for convergence of solutions from the two codes. (AN).
Author: Todd A. Simons
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Parviz Moin
Publisher:
ISBN:
Category : Aerofoils
Languages : en
Pages : 18
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Book Description
Author: Bernard Geurts
Publisher: Springer Science & Business Media
ISBN: 9401712638
Category : Technology & Engineering
Languages : en
Pages : 543
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Book Description
This volume contains the proceedings of the 2001 DLES4 workshop. It describes and discusses state-of-the-art modeling and simulation approaches for complex flows. Fundamental turbulence and modeling issues but also elements from modern numerical analysis are at the heart of this field of interest.
Author: Peter R. Voke
Publisher: Springer Science & Business Media
ISBN: 9780792331063
Category : Technology & Engineering
Languages : en
Pages : 454
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Book Description
It is a truism that turbulence is an unsolved problem, whether in scientific, engin eering or geophysical terms. It is strange that this remains largely the case even though we now know how to solve directly, with the help of sufficiently large and powerful computers, accurate approximations to the equations that govern tur bulent flows. The problem lies not with our numerical approximations but with the size of the computational task and the complexity of the solutions we gen erate, which match the complexity of real turbulence precisely in so far as the computations mimic the real flows. The fact that we can now solve some turbu lence in this limited sense is nevertheless an enormous step towards the goal of full understanding. Direct and large-eddy simulations are these numerical solutions of turbulence. They reproduce with remarkable fidelity the statistical, structural and dynamical properties of physical turbulent and transitional flows, though since the simula tions are necessarily time-dependent and three-dimensional they demand the most advanced computer resources at our disposal. The numerical techniques vary from accurate spectral methods and high-order finite differences to simple finite-volume algorithms derived on the principle of embedding fundamental conservation prop erties in the numerical operations. Genuine direct simulations resolve all the fluid motions fully, and require the highest practical accuracy in their numerical and temporal discretisation. Such simulations have the virtue of great fidelity when carried out carefully, and repre sent a most powerful tool for investigating the processes of transition to turbulence.
Author: M. Lesieur
Publisher: Cambridge University Press
ISBN: 9780521781244
Category : Mathematics
Languages : en
Pages : 240
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Book Description
Large-Eddy Simulations of Turbulence is a reference for LES, direct numerical simulation and Reynolds-averaged Navier-Stokes simulation.
Author: Trong T. Bui
Publisher:
ISBN:
Category : Parallel computers
Languages : en
Pages : 28
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Book Description
Author: Eric Garnier
Publisher: Springer Science & Business Media
ISBN: 9048128196
Category : Science
Languages : en
Pages : 280
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Book Description
This book addresses both the fundamentals and the practical industrial applications of Large Eddy Simulation (LES) in order to bridge the gap between LES research and the growing need to use it in engineering modeling.
