Large-eddy simulations of incompressible and subsonic shear flows

Lesieur, Marcel; Comte, Pierre; Métais, Olivier; Briand, Emmanuel; Delcayre, F.; Lamballais, Éric; Silvestrini, Jorge Hugo

doi:10.1007/bfb0106097

Cited by 4 publications

(9 citation statements)

References 19 publications

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“…This localised pairing can be seen in the light colours in the plan view taking a corrugated appearance in this region of the flow. This type of localised pairing has been observed in many other simulations of the plane mixing later with a pseudo-random white noise fluctuation environment, 22,24,26 and is sometimes referred to as giving the vortex structure a chain-link fence appearance. Once the streamwise structure has formed, a further interaction between the primary vortices precipitates the transition to turbulence in the mixing layer.…”

Section: Large Scale Spanwise Structure a Flow Visualisationmentioning

confidence: 59%

“…These localised interactions have been observed in experiments, 11 temporal mixing layer simulations with random noise perturbations, 50 and spatially-developing mixing layer simulations with inflow disturbances provided by low-level, three-dimensional random noise. 22,24,51 The perspective view recorded at station 3 ( Figure 17b) shows that the primary vortex structure has become very irregular. Branches and dislocations in the primary structure are visible throughout the trace, indicating that localised pairings are common at this streamwise position.…”

Section: Pre-transition Vorticesmentioning

confidence: 99%

“…Initially-laminar spatial mixing layer simulation inflow conditions are typically produced from a base mean velocity profile onto which pseudo-random white noise fluctuations are superimposed at each time step. 21,23,24,25 In the pre-transition region the nature of the imposed disturbances influences the nature of the laminar vortices. Three-dimensional random disturbances result in structures which undergo localised pairings, whilst highly two-dimensional random disturbances produce concentrated streamwise vortices between the primary rollers.…”

Section: Introductionmentioning

confidence: 99%

“…Three-dimensional random disturbances result in structures which undergo localised pairings, whilst highly two-dimensional random disturbances produce concentrated streamwise vortices between the primary rollers. 24 Whilst these studies were limited to the pre-transition region, more recent research has shown that simulation of initially laminar mixing layers with pseudorandom inflow disturbances leads to post-transition large-scale coherent structures which grow continuously and linearly throughout their lifetimes. 23 Flow visualisation of the high Reynolds number simulated flow shows that streamwise vorticity develops in the mixing layer, and that the streamwise vorticity persists far into the turbulent region.…”

Section: Introductionmentioning

confidence: 99%

“…This type of fluctuation environment is commonly used in DNS database simulations, 21,32 and in Large Eddy Simulations of the mixing layer. 23,24 A further simulation is performed where the disturbance environment is generated using a recycling and rescaling method. 30 The origin and evolution of the streamwise vorticity in both simulations will be analysed and compared to relevant experimental data where appropriate.…”

Section: Introductionmentioning

confidence: 99%

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Initial condition effects on large scale structure in numerical simulations of plane mixing layers

McMullan

Garrett

2016

Physics of Fluids

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In this paper Large Eddy Simulations are performed on the spatially developing plane turbulent mixing layer. The simulated mixing layers originate from initially laminar conditions. The focus of this research is on the e↵ect of the nature of the imposed fluctuations on the large-scale spanwise and streamwise structures in the flow. Two simulations are performed; one with low-level three-dimensional inflow fluctuations obtained from pseudo-random numbers, the other with physically-correlated fluctuations of the same magnitude obtained from an inflow generation technique. Where white-noise fluctuations provide the inflow disturbances, no spatially stationary streamwise vortex structure is observed, and the large-scale spanwise turbulent vortical structures grow continuously and linearly. These structures are observed to have a three-dimensional internal geometry with branches and dislocations. Where physically-correlated provide the inflow disturbances a 'streaky' streamwise structure that is spatially stationary is observed, with the large-scale turbulent vortical structures growing with the square-root of time. These large-scale structures are quasi-two-dimensional, on top of which the secondary structure rides. The simulation results are discussed in the context of the varying interpretations of mixing layer growth that have been postulated. Recommendations are made concerning the data required from experiments in order to produce accurate numerical simulation recreations of real flows.

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Section: Large Scale Spanwise Structure a Flow Visualisationmentioning

confidence: 59%

Section: Pre-transition Vorticesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Initial condition effects on large scale structure in numerical simulations of plane mixing layers

McMullan

Garrett

2016

Physics of Fluids

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Emergence of coherent flow structures over a gravel surface: A numerical experiment

Hardy

Lane

Ferguson

et al. 2007

Water Resources Research

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[1] Gravel bed rivers have complex, porous, and irregular surfaces, characterized by a range of morphological forms. These topographical structures determine the flow structures that develop over the river bed, primarily by the shedding of vortices in the downstream wake of protruding clasts. Previous research into these flow structures has come from experimental studies, which have used either flow visualization or single-point measurements techniques. Here we present a numerical experiment where large-eddy simulation (LES) is used to study the generation, evolution, and destruction of these flow structures over a naturally water worked gravel surface. The numerical simulations reported in this paper show that there are two distinct scales of boundary influence upon the shallow flow and emphasize that the measured flow variability at any one point in a natural river will contain both locally derived and upstream-inherited flow structures, according to the range of scales of bed topography present.

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Film Cooling Analysis Using DES Turbulence Model

Roy

Kapadia

Heidmann

2003

Volume 6: Turbo Expo 2003, Parts a and B

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The complex dynamic nature of the spanwise vortices in film cooling of turbine blades makes it necessary to accurately model the flow field temporally and spatially using detailed simulation techniques like direct numerical simulation or large eddy simulation of turbulence. Although, the later requires less computational effort and thus can simulate flows at higher Reynolds number than direct simulation, both these methods remain very expensive. As a viable alternative, this paper presents a Spalart-Allamaras based detached eddy simulation (DES) that is applied to a film cooled flat plate for the first time. The numerical model uses an unstructured grid system to resolve the dynamic flow structures on both sides of the plate as well as inside the hole itself. Detailed computation of a single row of 35 degree round holes on a flat plate has been obtained for blowing ratio of 1.0, and a density ratio of 2.0. The DES solution is also benchmarked with Reynolds averaged Navier-Stokes formulation for the same blade-hole configuration. The comparison shows that the DES simulation, which makes no assumption of isotropy downstream of the hole, greatly enhances the realistic description of the dynamic mixing processes.

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Large-eddy simulations of incompressible and subsonic shear flows

Cited by 4 publications

References 19 publications

Initial condition effects on large scale structure in numerical simulations of plane mixing layers

Initial condition effects on large scale structure in numerical simulations of plane mixing layers

Emergence of coherent flow structures over a gravel surface: A numerical experiment

Film Cooling Analysis Using DES Turbulence Model

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