scholarly journals ILES and LES of Complex Engineering Turbulent Flows

2007 ◽  
Vol 129 (12) ◽  
pp. 1514-1523 ◽  
Author(s):  
C. Fureby
Keyword(s):  
Turbulent Flows ◽  
Compressible Flows ◽  
Incompressible Flows ◽  
Phase Changes ◽  
Aerodynamic Noise ◽  
Complex Geometries ◽  
Flow Problems ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Complex Engineering

The present study concerns the application of large eddy simulation (LES) and implicit LES (ILES) to engineering flow problems. Such applications are often very complicated, involving both complex geometries and complex physics, such as turbulence, chemical reactions, phase changes, and compressibility. The aim of the study is to illustrate what problems occur when attempting to perform such engineering flow calculations using LES and ILES, and put these in relation to the issues originally motivating the calculations. The issues of subgrid modeling are discussed with particular emphasis on the complex physics that needs to be incorporated into the LES models. Results from representative calculations, involving incompressible flows around complex geometries, aerodynamic noise, compressible flows, combustion, and cavitation, are presented, discussed, and compared with experimental data whenever possible.

Development of a Spectral Element DNS/LES Method for Turbulent Flow Simulations

2007 ◽  
Author(s):  
Xu Zhang ◽  
Dan Stanescu ◽  
Jonathan W. Naughton
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Turbulent Flows ◽  
Compressible Flows ◽  
Time Integration ◽  
Flow Simulation ◽  
Spectral Element ◽  
Order Of Accuracy ◽  
Eddy Simulation ◽  
Large Eddy

This paper describes a turbulent flow simulation method, which is based on combination of spectral element and large eddy simulation (LES) technique. The robust, high-order discontinuous Galerkin (DG) spectral element method for large-eddy simulation of compressible flows allows for arbitrary order of accuracy and has excellent stability properties. A local spectral discretization in terms of Legendre polynomials is used on each element of the (possibly unstructured) mesh, which allows for high-accurate simulations of turbulent flows. Discontinuities across the interfaces of the elements are resolved using a Riemann solver. An isoparametric representation of the geometry is implemented, with boundaries of the domain discretized to the same order of accuracy as the solution, and explicit low-storage Runge-Kutta methods are used for time integration. Large eddy simulation has proven to be a valuable technique for the calculation of turbulent flows. An element based filtering technique is used in conjunction with the standard Smagorinsky eddy viscosity model to estimate the effect of sub-grid scales stresses in this paper. The recently developed nonlinear model [1] will also be added in the future. The final aim of this project is to use the LES methodology in swirling jet flow simulation. As a first step towards these simulations, simulations of compressible turbulent mixing layer and back-facing step are also performed to evaluate the robust method. Initial results based on both DNS and large eddy simulations are presented in this paper. Future work will be to validate the code.

ParNAS3D: LES Spray Simulation Using an Efficient Parallel Multidimensional Upwind Algorithm

1999 ◽  
Author(s):  
Doru Caraeni ◽  
Christer Bergstrom ◽  
Laszlo Fuchs
Keyword(s):  
Turbulent Flows ◽  
Message Passing ◽  
Compressible Flows ◽  
Industrial Applications ◽  
Residual Distribution ◽  
Flow Solver ◽  
Turbine Engine ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Distribution Scheme

Abstract A parallel flow-solver, ParNASSD1, has been developed at LTH2 for simulations of compressible flows in aeronautical and complex industrial applications. The Large Eddy Simulation (LES) technique is used to simulate turbulent flows. The code employs an efficient algorithm, based on the Residual Distribution Scheme approach, well suited for parallelization. It has been implemented in the SPMD paradigm, and uses the PVM defacto standard for message passing. The ParNAS3D solver has been coupled with an independent spray-module, for LES of spray in compressible flows. This was also done using the PVM message passing system. The combined LES-spray code has been used to investigate the injection, mixing and evaporation processes of a fuel spray in a gas turbine engine. The code proved to have an excellent scalability, both when running with and without the spray module. This is the first report on the implementation of the ParNAS3D parallel algorithm. We present also the numerical algorithm employed in our code.

A Subdomain Method for the Aeroacoustic Simulation of a Generic Side View Mirror

2013 ◽  
Vol 437 ◽  
pp. 321-324
Author(s):  
Li Na Huang ◽  
Ming Xin Xue ◽  
Hao Dong ◽  
Bo Yang
Keyword(s):  
Flow Field ◽  
Aerodynamic Noise ◽  
Complex Geometries ◽  
Side View ◽  
Cell Numbers ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Subdomain Method ◽  
Aeroacoustic Simulation ◽  
Good Agreement

The aerodynamic noise caused by the flow field around a generic side view mirror (SVM) was simulated using a subdomain large eddy simulation (LES) method. In this method, the LES solution could be run only in the subdomain, which can be the flow field near the SVM. The subdomain LES results show good agreement with the cited experimental data in some related works. With the principal advantage of saving CFD cell numbers, the subdomain LES method would be a perspective way to simulate the aerodynamic noise of complex geometries such as the real automobiles.

Large-Eddy Simulation of Turbulent Flow Through Small Gage Gas Appliance Orifices

2009 ◽  
Author(s):  
Emad Y. Tanbour ◽  
Ramin K. Rahmani ◽  
Anahita Ayasoufi
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Compressible Flows ◽  
Incompressible Flows ◽  
Large Diameter ◽  
Flow Characteristics ◽  
Eddy Simulation ◽  
Discrete Equations ◽  
Large Eddy ◽  
Flow Through

Small orifices are widely used in different industries including gas appliances. Although characteristics of orifices such as their coefficient of discharge have been subject of interest for the past several decades, most of the previous studies focus on relatively high Reynolds number flow through relatively large diameter orifices. Moreover, the majority of previous work has focused on incompressible flows. This study focuses on the flow of different compressible gaseous fluids inside small orifices ranging from 1.3 mm to 2.1 mm hydraulic diameters for flow Re numbers of ∼8000 to ∼26000. Large-Eddy Simulation for turbulent flow is employed to solve the second-order discrete equations for compressible and incompressible flows in gas appliance orifices to predict the flow characteristics for relatively low-Re compressible flows in orifices widely used in gas appliance industry. The impacts of fluid material, the orifice hydraulic diameter, and the orifice profile on the characteristics of orifice are studied.

Simulating Turbulent Flows in Complex Geometries

2003 ◽  
Author(s):  
Krishnan Mahesh ◽  
George Constantinescu ◽  
Parviz Moin
Keyword(s):  
Gas Turbine ◽  
Turbulent Flows ◽  
Complex Geometry ◽  
Reynolds Numbers ◽  
Complex Geometries ◽  
Gas Turbine Combustor ◽  
Turbine Engine ◽  
Eddy Simulation ◽  
Large Eddy ◽  
High Reynolds

We discuss development of a numerical algorithm, and solver capable of performing large-eddy simulation (LES) in geometries as complex as the combustor of a gas-turbine engine. The algorithm is developed for unstructured grids, is non-dissipative, yet robust at high Reynolds numbers on highly skewed grids. Results from validation in simple geometries is shown along with simulation results in the exceedingly complex geometry of a Pratt & Whitney gas turbine combustor.

Direct Numerical Simulation Of Turbulent Flows

1996 ◽  
Author(s):  
Anthony Leonard
Keyword(s):  
Numerical Simulation ◽  
Turbulent Flows ◽  
Compressible Flows ◽  
Incompressible Flows ◽  
Isotropic Turbulence ◽  
Turbulent Channel Flow ◽  
Spectral Element ◽  
Von Neumann ◽  
Eddy Simulation ◽  
Parallel Supercomputers

The numerical simulation of turbulent flows has a short history. About 45 years ago von Neumann (1949) and Emmons (1949) proposed an attack on the turbulence problem by numerical simulation. But one could point to a beginning 20 years later when Deardorff (1970) reported on a large-eddy simulation of turbulent channel flow on a 24x20x14 mesh and a direct simulation of homogeneous, isotropic turbulence was accomplished on a 323 mesh by Orszag and Patterson (1972). Perhaps the arrival of the CDC 6600 triggered these initial efforts. Since that time, a number of developments have occurred along several fronts. Of course, faster computers with more memory continue to become available and now, in 1994, 2563 simulations of homogeneous turbulence are relatively common with occasional 5123 simulations being achieved on parallel supercomputers (Chen et al., 1993) (Jimenez et al., 1993). In addition, new algorithms have been developed which extend or improve capabilities in turbulence simulation. For example, spectral methods for the simulation of arbitrary homogeneous flows and the efficient simulation of wall-bounded flows have been available for some time for incompressible flows and have recently been extended to compressible flows. In addition fast, viscous vortex methods and spectral element methods are now becoming available, suitable for incompressible flow with complex geometries. As a result of all these developments, the number of turbulence simulations has been increasing rapidly in the past few years and will continue to do so. While limitations exist (Reynolds, 1990; Hussaini et al., 1990), the potential of the method will lead to the simulation of a wide variety of turbulent flows. In this chapter, we present examples of these new developments and discuss prospects for future developments.

Simulating flow separation from continuous surfaces: routes to overcoming the Reynolds number barrier

2009 ◽  
Vol 367 (1899) ◽  
pp. 2885-2903 ◽  
Author(s):  
Michael Leschziner ◽  
Ning Li ◽  
Fabrizio Tessicini
Keyword(s):  
Reynolds Number ◽  
Turbulent Flows ◽  
Major Elements ◽  
Wall Layer ◽  
Navier Stokes ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Rans Models ◽  
High Reynolds ◽  
Near Wall

This paper provides a discussion of several aspects of the construction of approaches that combine statistical (Reynolds-averaged Navier–Stokes, RANS) models with large eddy simulation (LES), with the objective of making LES an economically viable method for predicting complex, high Reynolds number turbulent flows. The first part provides a review of alternative approaches, highlighting their rationale and major elements. Next, two particular methods are introduced in greater detail: one based on coupling near-wall RANS models to the outer LES domain on a single contiguous mesh, and the other involving the application of the RANS and LES procedures on separate zones, the former confined to a thin near-wall layer. Examples for their performance are included for channel flow and, in the case of the zonal strategy, for three separated flows. Finally, a discussion of prospects is given, as viewed from the writer's perspective.

Sign in / Sign up

Export Citation Format

Share Document