Wall-resolved wavelet-based adaptive large-eddy simulation of bluff-body flows with variable thresholding

2016 ◽  
Vol 788 ◽  
pp. 303-336 ◽  
Author(s):  
Giuliano De Stefano ◽  
Alireza Nejadmalayeri ◽  
Oleg V. Vasilyev
Keyword(s):  
Turbulent Flows ◽  
Bluff Body ◽  
Large Eddy Simulations ◽  
Eddy Simulation ◽  
Computational Mesh ◽  
Large Eddy ◽  
High Reynolds ◽  
The One ◽  
Solid Obstacles ◽  
Bluff Body Flows

The wavelet-based eddy-capturing approach with variable thresholding is extended to bluff-body flows, where the obstacle geometry is enforced through Brinkman volume penalization. The use of a spatio-temporally varying threshold allows one to perform adaptive large-eddy simulations with the prescribed fidelity on a near optimal computational mesh. The space–time evolution of the threshold variable is achieved by solving a transport equation based on the Lagrangian path-line diffusive averaging methodology. The coupled wavelet-collocation/volume-penalization approach with variable thresholding is illustrated for a turbulent incompressible flow around an isolated stationary prism with square cross-section. Wavelet-based adaptive large-eddy simulations supplied with the one-equation localized dynamic kinetic energy-based model are successfully performed at moderately high Reynolds number. The present study demonstrates that the proposed variable thresholding methodology for wavelet-based modelling of turbulent flows around solid obstacles is feasible, accurate and efficient.

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.

Large-Eddy Simulation of Roughened NACA65 Compressor Cascade

2017 ◽  
Author(s):  
Jongwook Joo ◽  
Gorazd Medic ◽  
Om Sharma
Keyword(s):  
Surface Roughness ◽  
Large Eddy Simulations ◽  
Surface Imaging ◽  
Potential Solution ◽  
Discrete Elements ◽  
Compressor Cascade ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Rans Modeling ◽  
The One

Large eddy simulations over a NACA65 compressor cascade with roughness were performed for multiple roughness heights. The experiments show flow separation as airfoil roughness is increased. In LES computations, surface roughness was represented by regularly arranged discrete elements using guidelines from Schlichting. Results from wall-resolved LES indicate that specifying an equivalent sandgrain roughness height larger than the one in experiments is required to reproduce the same effects observed in experiments. This highlights the persisting uncertainty with matching the experimental roughness geometry in LES computations, pointing towards surface imaging and digitization as a potential solution. Some initial analysis of flow physics has been conducted with the aim of guiding the RANS modeling for roughness.

scholarly journals Wall-modeled large-eddy simulation of the flow past a rod-airfoil tandem by the Lattice Boltzmann method

2018 ◽  
Vol 28 (5) ◽  
pp. 1096-1116 ◽  
Author(s):  
Emmanuel Leveque ◽  
Hatem Touil ◽  
Satish Malik ◽  
Denis Ricot ◽  
Alois Sengissen
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flows ◽  
Lattice Boltzmann ◽  
Early Stage ◽  
Content Type ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Turbulent Airflow ◽  
High Reynolds ◽  
Boltzmann Method

Purpose The Lattice Boltzmann (LB) method offers an alternative to conventional computational fluid dynamics (CFD) methods. However, its practical use for complex turbulent flows of engineering interest is still at an early stage. This paper aims to outline an LB wall-modeled large-eddy simulation (WMLES) solver. Design/methodology/approach The solver is dedicated to complex high-Reynolds flows in the context of WMLES. It relies on an improved LB scheme and can handle complex geometries on multi-resolution block structured grids. Findings Dynamic and acoustic characteristics of a turbulent airflow past a rod-airfoil tandem are examined to test the capabilities of this solver. Detailed direct comparisons are made with both experimental and numerical reference data. Originality/value This study allows assessing the potential of an LB approach for industrial CFD applications.

Experiments and Large-Eddy Simulations of acoustically forced bluff-body flows

2010 ◽  
Vol 31 (5) ◽  
pp. 754-766 ◽  
Author(s):  
S. Ayache ◽  
J.R. Dawson ◽  
A. Triantafyllidis ◽  
R. Balachandran ◽  
E. Mastorakos
Keyword(s):  
Bluff Body ◽  
Large Eddy Simulations ◽  
Large Eddy ◽  
Bluff Body Flows

scholarly journals Impact of dynamic subgrid-scale modeling in variational multiscale large-eddy simulation of bluff-body flows

2014 ◽  
Vol 225 (12) ◽  
pp. 3309-3323 ◽  
Author(s):  
Carine Moussaed ◽  
Stephen Wornom ◽  
Maria-Vittoria Salvetti ◽  
Bruno Koobus ◽  
Alain Dervieux
Keyword(s):  
Large Eddy Simulation ◽  
Bluff Body ◽  
Subgrid Scale ◽  
Variational Multiscale ◽  
Eddy Simulation ◽  
Scale Modeling ◽  
Large Eddy ◽  
Subgrid Scale Modeling ◽  
Bluff Body Flows

Similarities in the Development of Numerical Schemes and Sub-Grid Modeling in Large-Eddy Simulations

2009 ◽  
Author(s):  
L. E. B. Sampaio ◽  
A. O. Nieckele
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flows ◽  
Passive Scalar ◽  
Large Eddy Simulations ◽  
Wave Number ◽  
Numerical Schemes ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Mesh Spacing ◽  
Discretization Errors

Schemes for the discretization of spatial derivatives commonly employed in the numerical solution of Partial Differential Equations present intrinsic errors that become more important as the wave number content of solution field approaches the Nyquist criteria based on the mesh spacing. In many situations, this can be overcome by simply refining the mesh, so that the wavelength of the structures becomes much larger than the mesh spacing, and the discretization errors become again negligible. However, in some other cases, like in Large-Eddy Simulations of highly turbulent flows, the cost per discretization element is so high that further mesh refinement is prohibitive. In this case, it is more appropriate to work towards understanding and improving the numerical schemes, so that the wider possible range of the spectrum is accurately resolved, and the fewest possible number of degrees of freedom is needed to provide a satisfactory solution. By analyzing the similarities between the problems faced by numerical schemes and the challenges of sub-grid modeling in Large-Eddy Simulations (LES), an alternative for the numerical simulation of turbulence in the context of Large-Eddy Simulation is developed, that accumulates two main functionalities: represent the interaction between unresolved and resolved scales, while keeping the discretization errors at acceptable levels. The proposed scheme is of advective nature and has been applied in several test cases, ranging from simple one-dimensional convection of a passive scalar, to more complex turbulent flows. As a result, a better understanding of the role of discretization errors in Large-Eddy Simulation was obtained.

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