On the effects of nonequilibrium on the subgrid-scale stresses

Piomelli, Ugo; Coleman, Gary N.; Kim, John

doi:10.1063/1.869385

Cited by 19 publications

(12 citation statements)

References 17 publications

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“…This parameter can also be dynamically adjusted [22,23], as already done in [24] to simulate homogeneous turbulence inside a periodic cube by using a fourth order compact scheme. Equation (4) gives /η = π 1/6 = 1 when Re = 1 and ν = ν η , i.e., when the local scale is laminar; this is a consequence of the circular cross-section assumption used to describe the eddies in the fractal cascade. This has no importance as it increases the effective viscosity of the flow by ∼10 −3 µ [see Eq.…”

Section: Fm Closure Of Turbulent Combustionmentioning

confidence: 98%

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The coupling of turbulence and chemistry in a premixed bluff-body flame as studied by LES

Giacomazzi

Battaglia²,

Bruno

2004

Combustion and Flame

111

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Section: Fm Closure Of Turbulent Combustionmentioning

confidence: 98%

“…In the latter case, small scales are modeled considering their dissipative nature and assuming equilibrium [4,5]. For reactive problems, successful LES is still a goal because chemistry occurs at nonresolved dissipative length scales, where reactants mix at the molecular level, and the combustion process must be completely modeled.…”

Section: Introductionmentioning

confidence: 99%

The coupling of turbulence and chemistry in a premixed bluff-body flame as studied by LES

Giacomazzi

Battaglia²,

Bruno

2004

Combustion and Flame

111

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“…(36) (e.g., see Piomelli et al 1997). Representing the length scale in terms of the maximum resolved wavenumber of the LES yields, sgs = ( k 2 max ) ?1=3 ;…”

Section: A Posteriori Tests Using Lesmentioning

confidence: 99%

On the prediction of gas–solid flows with two-way coupling using large eddy simulation

Boivin¹,

Simonin²,

Squires³

2000

Physics of Fluids

163

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The purpose of this paper is to examine the feasibility of large eddy simulation (LES) for predicting gas-solid ows in which the carrier ow turbulence is modi ed by momentum exchange with particles. Several a priori tests of subgrid-scale (SGS) turbulence models are conducted utilising results from direct numerical simulation (DNS) of a forced homogeneous isotropic turbulent ow with the back e ect of the particles modelled using the point-force approximation. Properties of the subgrid-scale eld are computed by applying Gaussian lters to the DNS database. Similar to the behavior observed in single-phase ows, a priori test results show that, while the local energy ux is inaccurately estimated, the overall SGS dissipation is reasonably predicted using the conventional Smagorinsky model and underestimated using the Bardina scale-similarity model. Very good agreement between model predictions and DNS results are measured using closures whose coe cients are computed using the resolved eld, the so-called dynamic subgrid models, with the mixed model yielding more accurate predictions than the dynamic Smagorinsky model. A priori test results are then con rmed in actual LES calculations used to investigate the sensitivity of the predictions to mesh re nement. The LES was performed at in nite turbulent Reynolds number and for a range of particle response times and mass loadings. Grid resolution in the LES was varied from 32 3 to 96 3 collocation points, with particle sample sizes of 885; 000 for each response time. LES predictions of the ow with two-way coupling are independent of mesh re nement when using the dynamic mixed model and when the particle relaxation time becomes larger than the characteristic time scale of the unresolved uid turbulent eld.

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“…This type of sequence also exists for turbulence below surface waves (Teixeira & Belcher 2002), and in internal combustion engines (Hadzic, Hanjalic & Laurence 2001). SGS physics and modelling in non-equilibrium conditions were studied also by Piomelli, Coleman & Kim (1997) in suddenly accelerated or sheared wall-layers.…”

Section: Introductionmentioning

confidence: 99%

Scale interactions of turbulence subjected to a straining–relaxation–destraining cycle

Meneveau

Katz

2006

J. Fluid Mech.

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The response of turbulence subjected to planar straining and de-straining is studied experimentally, and the impact of the applied distortions on the energy transfer across different length scales is quantified. The data are obtained using planar particle image velocimetry (PIV) in a water tank, in which high-Reynolds-number turbulence with very low mean velocity is generated by an array of spinning grids. Planar straining and de-straining mean flows are produced by pushing and pulling a rectangular piston towards, and away from, the bottom wall of the tank. The data are processed to yield the time evolution of Reynolds stresses, anisotropy tensors, turbulence kinetic energy production, and mean subgrid-scale (SGS) dissipation rate at various scales. During straining, the production rises rapidly. After the relaxation period the small-scale SGS stresses recover isotropy, but the Reynolds stresses still display significant anisotropy. Thus when destraining is applied, a strong negative production (mean backscatter) occurs, i.e. the turbulence returns kinetic energy to the mean flow. The SGS dissipation displays similar behaviour at large filter scales, but the mean backscatter gradually disappears with decreasing filter scales. Energy spectra are compared to predictions of rapid distortion theory (RDT). Good agreement is found for the initial response but, as expected for the timescale ratios of the experiment, turbulence relaxation causes discrepancies between measurements and RDT at later times.

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On the effects of nonequilibrium on the subgrid-scale stresses

Cited by 19 publications

References 17 publications

The coupling of turbulence and chemistry in a premixed bluff-body flame as studied by LES

The coupling of turbulence and chemistry in a premixed bluff-body flame as studied by LES

On the prediction of gas–solid flows with two-way coupling using large eddy simulation

Scale interactions of turbulence subjected to a straining–relaxation–destraining cycle

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