Compressible Large Eddy Simulation Using Unstructured Grids PDF Download
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Author: Doyle D. Knight
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Languages : en
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Author: Doyle D. Knight
Publisher:
ISBN:
Category :
Languages : en
Pages :
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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.
Author: Gerald Urbin
Publisher:
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Category :
Languages : en
Pages :
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Author: Maria Vittoria Salvetti
Publisher: Springer
ISBN: 3030049159
Category : Technology & Engineering
Languages : en
Pages : 562
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Book Description
This book gathers the proceedings of the 11th workshop on Direct and Large Eddy Simulation (DLES), which was held in Pisa, Italy in May 2017. The event focused on modern techniques for simulating turbulent flows based on the partial or full resolution of the instantaneous turbulent flow structures, as Direct Numerical Simulation (DNS), Large-Eddy Simulation (LES) or hybrid models based on a combination of LES and RANS approaches. In light of the growing capacities of modern computers, these approaches have been gaining more and more interest over the years and will undoubtedly be developed and applied further. The workshop offered a unique opportunity to establish a state-of-the-art of DNS, LES and related techniques for the computation and modeling of turbulent and transitional flows and to discuss about recent advances and applications. This volume contains most of the contributed papers, which were submitted and further reviewed for publication. They cover advances in computational techniques, SGS modeling, boundary conditions, post-processing and data analysis, and applications in several fields, namely multiphase and reactive flows, convection and heat transfer, compressible flows, aerodynamics of airfoils and wings, bluff-body and separated flows, internal flows and wall turbulence and other complex flows.
Author: Todd Allen Simons
Publisher:
ISBN:
Category :
Languages : en
Pages : 280
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Book Description
Structured, unstructured, and zonal embedded grid finite volume formulations have been developed to solve the Favre filtered Navier-Stokes equations for performing large eddy simulation of turbulent flows. These compressible formulations were developed using a dual time stepping approach with low Mach number preconditioning. For the structured and zonal embedded grid formulations, time marching was done with either an explicit Runge-Kutta scheme or an implicit lower-upper symmetric-Gauss-Seidel scheme. For the unstructured formulation, time marching used either an explicit Runge-Kutta scheme or traditional Gauss-Seidel scheme. All codes were parallelized to reduce the overall time required for simulations. These schemes were second-order accurate in space and time. Validations were performed using laminar and turbulent incompressible benchmark flows.
Author: Richard H. Pletcher
Publisher:
ISBN:
Category : Eddies
Languages : en
Pages : 34
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Book Description
Large eddy simulation methods have been developed to compute compressible turbulent flows with heat transfer. The formulation employs preconditioning to permit efficient use in the low Mach number regime. Efficient algorithms have been developed for both vector and parallel processing computer systems. Simulation results have been obtained using a dynamic subgrid-scale model for a channel heated and cooled at temperature ratios as high as 3. Results were also obtained for a channel with uniform wall heat flux heating and cooling with wall to bulk temperature ratios as high as 1.5 for heating and 0.56 for cooling. Density rms fluctuations as high as 9% have been observed for very low Mach number flows with heat transfer. Mean and rms velocity and temperature data were observed to collapse toward incompressible results when plotted in semi-local coordinates. Preliminary results have also been obtained for flow in a rib-roughened channel. The large eddy simulation algorithms were extended to include the use of unstructured and zonal embedded grids. Particularly, the use of zonal embedded grids show much promise for extending the Reynolds number range for which large eddy simulation can be employed with existing computers.
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: Todd A. Simons
Publisher:
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Category :
Languages : en
Pages :
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Author: Mostafa Najafiyazdi
Publisher:
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Category :
Languages : en
Pages :
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"In Computational Aeroacoustic (CAA) applications of Large-Eddy Simulations (LES), accurate control over turbulent kinetic energy (TKE) dissipation is needed to minimize aliasing and obtain accurate broad-band noise estimations. Among different LES approaches, Approximate Deconvolution Models (ADM) allow direct control of the TKE dissipation rate for the resolvable wavenumber scales. This control is obtained by applying an explicitly defined spatial filter on the computed flow fields. InADM schemes, filtered Navier-Stokes equations are used where the filtering operator is explicitly defined. Approximate deconvolution approaches are used to estimate the unfiltered quantities used in constructing the nonlinear flux terms. Given a filter operator, the energy dissipation associated with filtering can be quantified. ADM has been successfully applied on structured grids using discrete high-order filter operators. Its application on unstructured grid has been very limited due to lack of a proper filter.The objective of the present work was to extend the application of Approximate Deconvolution Models (ADM) for LES on unstructured grids by using explicit differential filters. Germano’s elliptic differential filter was successfully extended to include two free parameters. One ensured full attenuation at grid cut-off wavenumber, preventing aliasing due to LES and stabilizing the numerical scheme. The other controlled the filter cut-off wavenumber. The discretized formulation of this differential filter was developed for two- and three-dimensional elements. Dissipation and dispersion properties of the discrete differential filter were investigated in detail.A second-order classical finite element method (FEM) was used for spatial discretization of the compressible Navier-Stokes equations. Time integration was performed through the use of the standard fourth-order explicit Runge-Kutta scheme. Interpolation on high resolution grids was used to obtain the fast Fourier transform (FFT) of the flow fields on perturbed and unstructured grids.Decaying isotropic homogeneous turbulence at Reynolds number 3, 400 was modeled on both structured and unstructured grids. Results were compared to a reference direct numerical simulation (DNS) and other LES results reported in the literature. The effect of mesh anisotropy on the newly proposed differential filter performance was studied. It was observed that stable and sufficiently accurate LES results could be obtained on unstructured grids, even in the presence of highly skewed elements. Careful examination of the dissipation rate in the resolved wavenumbers suggested that grid anisotropy induces different cut-off wavenumbers in different directions resulting in higher dissipation rates than those obtained on an isotropic mesh.Taylor-Green vortex (TGV) was also studied as an excellent canonical problem for laminar to turbulence transition of a flow. LES simulations using the ADM framework were conducted in which the filter extended to three-dimensional elements was used. Investigative studies on the ADM order, the ADM under-relaxation coefficient, the degree of anisotropy in the grid, and grid resolution were performed to benchmark the filter performance in conjunction with ADM. Finally, an LES of TGV on a fully unstructured grid was performed showing the range of application of the proposed filter"--
Author: Doyle Knight
Publisher: Springer Science & Business Media
ISBN: 940114513X
Category : Technology & Engineering
Languages : en
Pages : 516
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Book Description
This collection of papers presents a broad range of topics in DNS and LES, from new developments in LES modeling to DNS and LES for supersonic and hypersonic boundary layers. The book provides an extensive view of the state of the art in the field.
