Large eddy simulation of a nonpremixed reacting jet: Application and assessment of subgrid-scale combustion models

DesJardin, Paul E.; Frankel, Steven

doi:10.1063/1.869749

Cited by 149 publications

(87 citation statements)

References 43 publications

(43 reference statements)

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“…Subgrid-scale models The introduction of the dynamic model proposed by Germano et al (1991) has spurred significant progress in the subgrid-scale (SGS) modelling of non-equilibrium flows. Among the various SGS turbulence models, such as the mixed model (Fureby 1996) and the two-parameter mixed model (Salvetti & Banerjee 1995), the dynamic SGS model for turbulence closure offers the best trade-off between accuracy and cost (Desjardin & Frankel 1998). In the present study, the dynamic Smagorinsky model for compressible flows proposed by Moin et al (1991) is employed.…”

Section: Mathematical Formulation and Numerical Methodsmentioning

confidence: 99%

Large-eddy simulation of the compressible flow past a wavy cylinder

Chen

2010

J. Fluid Mech.

112

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Numerical investigation of the compressible flow past a wavy cylinder was carried out using large-eddy simulation for a free-stream Mach number M∞ = 0.75 and a Reynolds number based on the mean diameter Re = 2 × 105. The flow past a corresponding circular cylinder was also calculated for comparison and validation against experimental data. Various fundamental mechanisms dictating the intricate flow phenomena, including drag reduction and fluctuating force suppression, shock and shocklet elimination, and three-dimensional separation and separated shear-layer instability, have been studied systematically. Because of the passive control of the flow over a wavy cylinder, the mean drag coefficient of the wavy cylinder is less than that of the circular cylinder with a drag reduction up to 26%, and the fluctuating force coefficients are significantly suppressed to be nearly zero. The vortical structures near the base region of the wavy cylinder are much less vigorous than those of the circular cylinder. The three-dimensional shear-layer shed from the wavy cylinder is more stable than that from the circular cylinder. The vortex roll up of the shear layer from the wavy cylinder is delayed to a further downstream location, leading to a higher-base-pressure distribution. The spanwise pressure gradient and the baroclinic effect play an important role in generating an oblique vortical perturbation at the separated shear layer, which may moderate the increase of the fluctuations at the shear layer and reduce the growth rate of the shear layer. The analysis of the convective Mach number indicates that the instability processes in the shear-layer evolution are derived from oblique modes and bi-dimensional instability modes and their competition. The two-layer structures of the shear layer are captured using the instantaneous Lamb vector divergence, and the underlying dynamical processes associated with the drag reduction are clarified. Moreover, some phenomena relevant to the compressible effect, such as shock waves, shocklets and shock/turbulence interaction, are analysed. It is found that the shocks and shocklets which exist in the circular cylinder flow are eliminated for the wavy cylinder flow and the wavy surface provides an effective way of shock control. As the shock/turbulence interaction is avoided, a significant drop of the turbulent fluctuations around the wavy cylinder occurs. The results obtained in this study provide physical insight into the understanding of the mechanisms relevant to the passive control of the compressible flow past a wavy surface.

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Section: Mathematical Formulation and Numerical Methodsmentioning

confidence: 99%

Large-eddy simulation of the compressible flow past a wavy cylinder

Chen

2010

J. Fluid Mech.

112

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“…Among the various SGS turbulence models, such as the mixed model [13] and the two-parameter mixed model [14], the dynamic SGS model for turbulence closure offers the best trade-off between accuracy and cost [15]. In the present study, the dynamic Smagorinsky model for compressible flows proposed by Moin et al [16] is employed.…”

Section: Subgrid-scale Modelsmentioning

confidence: 99%

Large-eddy simulation of the compressible flow past a tabbed cylinder

Zhao

Sun

2012

Chin. Sci. Bull.

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The compressible flow past a tabbed cylinder has been studied numerically using large-eddy simulation for a free-stream Mach number M∞=0.75 and a Reynolds number based on the diameter Re=2×10 5 . Because of the passive control of the flow past a tabbed cylinder, the mean drag coefficient of tabbed cylinder is less than that of a corresponding circular cylinder with a drag reduction up to 33%. The fluctuating lift coefficient is greatly suppressed to be nearly zero. Drag reduction due to the shearing process prevails over that due to the compressing process in this flow. Through investigating the mechanisms relevant to passive control of the tab, it is found that suppression of the shear layer instability can lead to a higher-base-pressure distribution, which can reasonably be associated with drag reduction and suppression of the lift fluctuations. The analysis of convective Mach number and self-sustained oscillations phenomenon inside the shear layers indicates that both the compressible effect and high-frequency forcing result in suppression of the shear layer instability of tabbed cylinder. circular cylinder, shock wave, compressible turbulence, large-eddy simulation Citation:Xu C Y, Zhao L Q, Sun J H. Large-eddy simulation of the compressible flow past a tabbed cylinder.

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“…The model of Pierce and Moin 4 has been extensively used over the years 7,20,36,37 as an alternate to the scale-similarity model suggested by Cook and Riley 2 based on the idea of Bardina et al 38 The scale-similarity model has been explored in several different configurations. 3,7,39,40 Recently, Balarac et al, 5 using the optimal estimator concept of Moreau et al, 25 showed that the irreducible error associated with a Smagorinsky-type model is relatively small if compared to that evaluated for a scalesimilarity model, meaning that the functional form of a gradient-based model has significant potential in LES for reproducing the SGS scalar variance. This has also been observed by Wall et al 36 when studying the performance of the two models used in that study in conjunction with a presumed PDF approach.…”

Section: B the Dynamic Modelmentioning

confidence: 99%

The subgrid-scale scalar variance under supercritical pressure conditions

Masi

Bellan

2011

Physics of Fluids

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To model the subgrid-scale (SGS) scalar variance under supercritical-pressure conditions, an equation is first derived for it. This equation is considerably more complex than its equivalent for atmospheric-pressure conditions. Using a previously created direct numerical simulation (DNS) database of transitional states obtained for binary-species systems in the context of temporal mixing layers, the activity of terms in this equation is evaluated, and it is found that some of these new terms have magnitude comparable to that of governing terms in the classical equation. Most prominent among these new terms are those expressing the variation of diffusivity with thermodynamic variables and Soret terms having dissipative effects. Since models are not available for these new terms that would enable solving the SGS scalar variance equation, the adopted strategy is to directly model the SGS scalar variance. Two models are investigated for this quantity, both developed in the context of compressible flows. The first one is based on an approximate deconvolution approach and the second one is a gradient-like model which relies on a dynamic procedure using the Leonard term expansion. Both models are successful in reproducing the SGS scalar variance extracted from the filtered DNS database, and moreover, when used in the framework of a probability density function (PDF) approach in conjunction with the b-PDF, they excellently reproduce a filtered quantity which is a function of the scalar. For the dynamic model, the proportionality coefficient spans a small range of values through the layer cross-stream coordinate, boding well for the stability of large eddy simulations using this model.

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Large eddy simulation of a nonpremixed reacting jet: Application and assessment of subgrid-scale combustion models

Cited by 149 publications

References 43 publications

Large-eddy simulation of the compressible flow past a wavy cylinder

Large-eddy simulation of the compressible flow past a wavy cylinder

Large-eddy simulation of the compressible flow past a tabbed cylinder

The subgrid-scale scalar variance under supercritical pressure conditions

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