Comparison of Subgrid-scale Viscosity Models and Selective Filtering Strategy for Large-eddy Simulations

Aubard, Guillaume; Volpiani, Pedro S.; Gloerfelt, Xavier; Robinet, Jean-Christophe

doi:10.1007/s10494-013-9485-5

Cited by 30 publications

(27 citation statements)

References 64 publications

(76 reference statements)

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“…The effects of unresolved scales are taken into account implicitly in the high-wavenumber range thanks to the smooth truncations of the filter and finite-difference schemes in the wavenumber space. The efficiency of this LES strategy has been previously demonstrated for TBL flows (Aubard et al 2013;Gloerfelt & Berland 2013).…”

Section: Methodsmentioning

confidence: 93%

Influence of pressure gradients on wall pressure beneath a turbulent boundary layer

Cohen

Gloerfelt

2018

J. Fluid Mech.

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This study investigates the effects of a pressure gradient on the wall pressure beneath equilibrium turbulent boundary layers. Excitation of the walls of a vehicle by turbulent boundary layers indeed constitutes a major source of interior noise and it is necessary to take into account the presence of a pressure gradient to represent the effect of the curvature of the walls. With this aim, large-eddy simulations of turbulent boundary layers in the presence of both mild adverse and mild favourable pressure gradients are carried out by solving the compressible Navier–Stokes equations. This method provides both the aeroacoustic contribution and the hydrodynamic wall-pressure fluctuations. A critical comparison with existing databases, including recent measurements, is conducted to assess the influence of a free stream pressure gradient. The analyses of wall-pressure spectral densities show an increase in the low-frequency content from adverse to favourable conditions, yielding higher integrated levels of pressure fluctuations scaled by the wall shear stress. This is accompanied by a steeper decay rate in the medium-frequency portion for adverse pressure gradients. No significant difference is found for the mean convection velocity. Frequency–wavenumber spectra including the subconvective region are presented for the first time in the presence of a pressure gradient. A scaling law for the convective ridge is proposed, and the acoustic domain is captured by the simulations. Direct acoustic emissions have similar features in all gradient cases, even if slightly higher levels are noted for boundary layers subjected to an adverse gradient.

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Section: Methodsmentioning

confidence: 93%

Influence of pressure gradients on wall pressure beneath a turbulent boundary layer

Cohen

Gloerfelt

2018

J. Fluid Mech.

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“…Another test case that is of relevance to this article, is the decay of the Taylor Green vortex [36][37][38]. It is the unsteady decay of a three dimensional (or two dimensional) velocity field specified by initial conditions defined by Taylor and Green [39].…”

Section: Conflicts Of Interestmentioning

confidence: 99%

Large Eddy Simulation with Energy-Conserving Schemes and the Smagorinsky Model: A Note on Accuracy and Computational Efficiency

et al. 2018

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Despite advances in turbulence modelling, the Smagorinsky model remains a popular choice for large eddy simulation (LES) due to its simplicity and ease of use. The dissipation in turbulence energy that the model introduces, is proportional to the Smagorinsky constant, of which many different values have been proposed. These values have been derived for certain simulated test-cases while using a specific set of numerical schemes, to obtain the correct dissipation in energy simply because an incorrect value of the Smagorinsky constant would lead to an incorrect dissipation. However, it is important to bear in mind that numerical codes may suffer from numerical or artificial dissipation, which occurs spuriously through a combination of spatio-temporal and iterative errors. The latter can be controlled through more iterations, the former however, depends on the grid resolution and the time step. Recent research suggests that a complete energy-conserving (EC) spatio-temporal discretisation guarantees zero numerical dissipation for any grid resolution and time step. Therefore, using an EC scheme would ensure that dissipation occurs primarily through the Smagorinsky model (and errors in its implementation) than through the discretisation of the Navier-Stokes (NS) equations. To evaluate the efficacy of these schemes for engineering applications, the article first discusses the use of an EC temporal discretisation as regards to accuracy and computational effort, to ascertain whether EC time advancement is advantageous or not. It was noticed that a simple non-EC explicit method with a smaller time step not only reduces the numerical dissipation to an acceptable level but is computationally cheaper than an implicit-EC scheme for wide range of time steps. Secondly, in terms of spatial discretisation on uniform grids (popular in LES), a simple central-difference scheme is as accurate as an EC spatial discretisation. Finally, following the removal of numerical dissipation with any of the methods mentioned above, one is able to choose a Smagorinsky constant that is nearly independent of the grid resolution (within realistic bounds, for OpenFOAM and an in-house code). This article provides impetus to the efficient use of the Smagorinsky model for LES in fields such as wind farm aerodynamics and atmospheric simulations, instead of more comprehensive and computationally demanding turbulence models.

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“…LES is a method of turbulence modelling that resolves spatially filtered flow fields (Aubard et al, 2013;Sagaut and Grohens, 1999). The method can be implemented as a local increase of the kinematic viscosity ν ν eff = ν + ν sgs (2.5) where ν eff is the effective local viscosity and ν sgs denotes the turbulent (or sub-grid scale, SGS) viscosity which in the model of Smagorinsky (1963) is computed as…”

Section: Large Eddy Simulation In Lbmmentioning

confidence: 99%

Application of the Lattice Boltzmann Method to the flow past a sphere

Kajzer

Pozorski

2017

jtam

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The results of fully resolved simulations and large eddy simulations of bluff-body flows obtained by means of the Lattice Boltzmann Method (LBM) are reported. A selection of Reynolds numbers has been investigated in unsteady laminar and transient flow regimes. Computed drag coefficients of a cube have been compared with the available data for validation purposes. Then, a more detailed analysis of the flow past a sphere is presented, including also the determination of vortex shedding frequency and the resulting Strouhal numbers. Advantages and drawbacks of the chosen geometry implementation technique, so called "staircase geometry", are discussed. For the quest of maximum computational efficiency, all simulations have been carried out with the use of in-house code executed on GPU.

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Comparison of Subgrid-scale Viscosity Models and Selective Filtering Strategy for Large-eddy Simulations

Cited by 30 publications

References 64 publications

Influence of pressure gradients on wall pressure beneath a turbulent boundary layer

Influence of pressure gradients on wall pressure beneath a turbulent boundary layer

Large Eddy Simulation with Energy-Conserving Schemes and the Smagorinsky Model: A Note on Accuracy and Computational Efficiency

Application of the Lattice Boltzmann Method to the flow past a sphere

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