Large eddy simulation of premixed flames in Couette flow

Menon, Suresh; Chakravarthy, V. Kalyana

doi:10.2514/6.1996-3077

Cited by 5 publications

(7 citation statements)

References 13 publications

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“…It is likely that the wall layer needs more resolution or the experimental results may be in error due to moving wall (belt) vibrations which make the flow noisy. This LES approach has earlier been validated by simulating turbulent Couette flow at Re of 5200 by comparing with experiments in [5]. In order to ease the implementation of LEM on LES grid, the mid 78 percent of the grid is made uniform.…”

Section: Resultsmentioning

confidence: 99%

“…Instead of picking these cells from a random location on the donor subgrid domain like in the earlier research [5], cells are tranfered from one end of the subgrid domain. The cells that are spliced in are put at the opposite end of the domain.…”

Section: Linear Eddy Subgrid Modelmentioning

confidence: 99%

“…Thus the constant of proportionality is arrived at from analytical reasoning rather than a calibrating procedure undertaken in [7]. Equating the value of diffusivity to the corresponding integrated effect of triplet mappings at various length scales, one can arrive at the PDF for length scale / and the stirring frequency (using the procedure adopted in [5]). The stirring procedure in conjunction with the molecular diffusion has been shown to effectively model the effect of three dimensional inertial range turbulence on the scalar fields [21].…”

Section: Linear Eddy Subgrid Modelmentioning

confidence: 99%

“…All spatial gradients are increased by a factor of 3 in the portions at the ends, and a factor of -3 in the middle portion. The scalar field in the three segments is pieced together to give a continuous scalar field with scalar values at the end points of the segment remaining the same as before and the scalar gradients increased by 3 times in magnitude (as illustrated in [5]). These increased gradients cause increased scalar diffusion in accordance with what has been observed as the effect of turbulence on scalar transport and dispersion.…”

Section: Linear Eddy Subgrid Modelmentioning

confidence: 99%

“…The kinematic structure of premixed flames was modeled earlier by Menon et al [4] and this approach was extended for modeling the kinematics of a self propagating scalar interface in a wall bounded shear flow using LES with dynamic A'-equation model [5]. This study utilized the G-equation [6] which models the motion of self propagating kinematic surface (model for cold flame).…”

Section: Introductionmentioning

confidence: 99%

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Characteristics of a subgrid model for turbulent premixed flames

Chakravarthy

Menont

1997

33rd Joint Propulsion Conference and Exhibit

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A modified version of the linear eddy model (LEM) for subgrid combustion is developed and used for studying the properties of turbulent premixed flames in the core region of Couette flow. The handling of the burning (diffusion/reaction) and specie transport, in this new approach, is fully deterministic. The model is, therefore, found to predict the correct laminar flame speed in the limit of zero turbulence. The effect of three dimensional eddies on scalar fields at the subgrid scales is modeled using a stochastic Lagrangian rearrangement procedure. The derivation of this procedure from the inertial range scaling laws necessitates a calibration procedure since the numerical values of the constants in these laws are unknown. The present LEM approach relates the constant needed to the coefficient of eddy viscosity that is evaluated in a LES, under the assumption of constant turbulent Prandtl and Schmidt numbers. The new approach is found to predict the turbulent flame speed with fair amount of accuracy. The chemistry is modeled using a self propagating scalar field (G-equation) approach and within the limitations of this model, LEM is found to capture the right trends in evolution of flame structure, effects of heat release and turbulence. The encouraging results obtained here warrant further research into extending this subgrid model for cases of finite rate chemistry and inclusion of thermodiffusive mechanisms such as the Lewis number effects.

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Section: Resultsmentioning

confidence: 99%

Section: Linear Eddy Subgrid Modelmentioning

confidence: 99%

Section: Linear Eddy Subgrid Modelmentioning

confidence: 99%

Section: Linear Eddy Subgrid Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characteristics of a subgrid model for turbulent premixed flames

Chakravarthy

Menont

1997

33rd Joint Propulsion Conference and Exhibit

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Hybrid Simulation Approach for Cavity Flows: Blending, Algorithm, and Boundary Treatment Issues

Baurle¹,

Tam²,

Edwards³

et al. 2003

AIAA Journal

138

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The maturation of high-performance computer architectures and computational algorithms has prompted the development of a new generation of models that attempt to combine the robustness and ef ciency offered by the Reynolds averaged Navier-Stokes equations with the higher level of modeling offered by the equations developed for large eddy simulation. The application of a new hybrid approach is discussed, where the transition between these equation sets is controlled by a blending function that depends on local turbulent ow properties, as well as the local mesh spacing. The utilization of local turbulence properties provides added control in specifying the regions of the ow intended for each equation set, removing much of the burden from the grid-generation process. Moreover, the model framework allows for the combination of existing closure model equations, avoiding the dif culty of formulating a single set of closure coef cients that perform well in both Reynolds averaged and large eddy simulation modes. Simple modi cations to common second-order accurate Reynolds averaged Navier-Stokes algorithmsare proposed to enhance the capturing of large eddy motions. Incompressible Poiseuille ow, supersonic base ow, and supersonic ow over recessed cavities were considered to evaluate various aspects of the proposed model and computational framework. Calculations using another hybrid approach (detached eddy simulation) were also performed for comparison. Nomenclature a i j = matrix of normalized velocity variances and covariances b = law of the wall intercept C D k! = cross-diffusion term for the speci c turbulent dissipation rate C d = constant for the destruction term of k C DES = constant for the detached eddy simulation (DES) length scale C p = pressure coef cient C s = constant for the Smagorinsky viscosity coef cient C ¹ = constant for the turbulent viscosity coef cient C ! p = constant for the production term of ! c = constant for the gradient sensor D = cavity depth d = distance to the nearest solid surface F = blending function F c ; F d ; F u = central, dissipative, and upwind contributions to the inviscid uxes f = joint normal distribution function h = channel height k = turbulent kinetic energỳ = turbulent length scale m = normalized cavity mass n;¯= constants for the latency parameter of Speziale 6 P = pressure P k = production term for the turbulent kinetic energy P ! = production term for the speci c turbulent dissipation rate q = MUSCL extrapolated variable R = sting base radius r = numerical dissipation reduction factor r; µ = polar coordinates t = time u i = velocity u ¿ = friction velocity V = turbulent velocity scale v i = velocity normalized with the rms of its uctuation x; y; z = Cartesian coordinates 1 = subgrid length scale ± i j = Kronecker delta ± C ; ± ¡ = nite difference operators (forward, backward) ² = turbulent dissipation rate or generic small numbeŕ = blending function argument · = MUSCL interpolation constant or law of the wall slope ¹ = viscosity coef cient º = speci c viscosity coef cient ...

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Subgrid modeling of unsteady two-phase turbulent flows

Menon

Pannala

1997

33rd Joint Propulsion Conference and Exhibit

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A subgrid scalar mixing and combustion model originally developed for gas phase combustion has been extended in this study to include the liquid phase. This approach includes a more fundamental treatment of the effects of the final stages of droplet vaporization, molecular diffusion, chemical reactions and small scale turbulent stirring than other LES closure techniques. As a result, Reynolds, Schmidt and Damkohler number effects are explicitly included. This model has been implemented within an Eulerian-Lagrangian two phase large-eddy simulation (LES) formulation. In this approach, the liquid droplets are tracked using the Lagrangian approach up to a pre-specified cut-off size. The evaporation and mixing of the droplets smaller than the cutoff size is modeled within the subgrid using an Eulerian two-phase model that is an extension of the earlier gas-phase subgrid model. The issues related to the implementation of this subgrid model within the LES are discussed in this paper along with some preliminary results that demonstrate its capabilities.

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Large eddy simulation of premixed flames in Couette flow

Cited by 5 publications

References 13 publications

Characteristics of a subgrid model for turbulent premixed flames

Characteristics of a subgrid model for turbulent premixed flames

Hybrid Simulation Approach for Cavity Flows: Blending, Algorithm, and Boundary Treatment Issues

Subgrid modeling of unsteady two-phase turbulent flows

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