Detailed characteristics of drop-laden mixing layers: Large eddy simulation predictions compared to direct numerical simulation

Okong’o, Nora; Leboissetier, Anthony; Bellan, Josette

doi:10.1063/1.2990758

Cited by 13 publications

(4 citation statements)

References 36 publications

(48 reference statements)

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“…Most simulations of engines with sprays have used existing RANS spray models with simple modifications for use with LES turbulence models. In a series of papers, Bellan et al have carried out extensive work exploring particle-based spray models for both DNS and LES simulations [135][136][137][138][139]. This is more fundamental work, but the target applications are those that use the Lagrangian parcel approach.…”

Section: Fuel-spray Modellingmentioning

confidence: 99%

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Large-eddy simulations for internal combustion engines – a review

Rutland

2011

International Journal of Engine Research

236

150

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A review of using large-eddy simulation (LES) in computational fluid dynamic studies of internal combustion engines is presented. Background material on turbulence modelling, LES approaches, specifically for engines, and the expectations of LES results are discussed. The major modelling approaches for turbulence, combustion, scalars, and liquid sprays are discussed. In each of these areas, a taxonomy is presented for the various types of models appropriate for engines. Advantages, disadvantages, and examples of use in the literature are described for the various types of models. Several recent examples of engine studies using LES are discussed. Recommendations and future prospects are included.

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Section: Fuel-spray Modellingmentioning

confidence: 99%

“…In a series of papers, Bellan et al . have carried out extensive work exploring particle-based spray models for both DNS and LES simulations [135–139]. This is more fundamental work, but the target applications are those that use the Lagrangian parcel approach.…”

Section: Les Models In Ic Enginesmentioning

confidence: 99%

Large-eddy simulations for internal combustion engines – a review

Rutland

2011

International Journal of Engine Research

236

150

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“…It will also be necessary to ultimately introduce more-accurate individual rate laws (e.g., for aggregate coagulation; see e.g., ref ) and address multivariate populations. However, the further development/exercise of this type of simulation tool, especially when compared with the results of corresponding physicochemical experiments, should prove useful to guide future modeling effortsincluding the development and testing of generalized turbulence models to enable the “time” variable to be suppressed for “(quasi)-steady-state” turbulent flowseither fully (as for Reynolds-time-averaged Navier−Stokes (RANS) simulations) or partially (as in more demanding “large-eddy” simulations (LES) (see, e.g., the recent work of Moin and Apte and Menon and Patel, and the recent fundamental studies of Okong’o et al).…”

Section: Toward More Comprehensive Pbe-based Modelsmentioning

confidence: 99%

Spray Combustor Design/Performance: Chemical Engineering Contributions and the Emergence of an “Interacting Population-Balance” Perspective

Rosner

2009

Ind. Eng. Chem. Res.

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Spray combustors are now widely used in many technologies, spanning commodity chemical synthesis (combustion of molten sulfur en route to sulfuric acid (H 2 SO 4 ) and phosphorus en route to phosphoric acid (H 3 PO 4 ), ...), and nanoparticle synthesis (eg., via "spray pyrolysis"), to energy conversion (oil-fired furnaces or boilers) and chemical propulsion (aircraft gas turbines and liquid-propellant rocket motors). While important space, weight, and pollutant constraints inevitably differ from application to application, spray-"fuel"-fed combustors share certain common performance characteristics, and there is a considerable economic incentive to develop rational yet tractable design methods for them. While this intrinsically interdisciplinary subject continues to evolve, here, we briefly review some of the principal contributions to these challenging goals published by chemical engineers since the inception of Industrial and Engineering Chemistry (I&EC). Not surprisingly, the earliest contributions focused on some of the important "unit processes" (e.g., isolated droplet evaporation rates, vapor micromixing rates in spatially homogeneous turbulent flows, and steady vaporphase laminar diffusion flames). Chemical engineers introduced "continuous mixture theory" to economically address not only phase/chemical equilibria in multicomponent mixtures, but also spatially nonuniform (nonequilibrium) flows. More-recent studies have introduced diffusion "flamelet" concepts for vapor-phase nonpremixed combustion and statistical population-balance concepts to address evolving turbulence characteristics and/or droplet size distributions. Because of the wide range of operative (length and time) scales in the full problem, in the foreseeable future, clever asymptotic methods will continue to be required to capture the essential physicochemical phenomena but still make the associated numerical simulations manageable. In this regard, a fruitful unified perspective is now emergingsone quite natural to chemical engineers. This can perhaps be best described as an interacting "multi-phase, multi-environment" approachsor simply an "interacting multivariable population balance" approach. While much remains to be done, it is hoped that this 2008/2009 perspective, and highly selective "review" of but one class of multiphase chemical reactors, will stimulate further activity along this promising path.

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“…In the vast majority of SGS models, the local structure of turbulence is assumed to be homogeneous, i.e. the gradients of the fluid flow variables in the vicinity of the droplet are estimated from filtered fields and not from their increments in the smallest turbulent motions on residual scales (Leboissetier, Okong'o & Bellan 2005;Pera et al 2006;Okong'o, Leboissetier & Bellan 2008;Apte, Mahesh & Moin 2009;Senoner et al 2009;Irannejad & Jaberi 2014;Tsang, Trujillo & Rutland 2014). This raises questions on how to account for SGS gradients in the fluid on the dynamics of evaporating droplets.…”

Section: Introductionmentioning

confidence: 99%

Stochastic models for the droplet motion and evaporation in under-resolved turbulent flows at a large Reynolds number

Gorokhovski

Oruganti

2021

J. Fluid Mech.

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In this work we introduce a Lagrangian stochastic model for particle motion and evaporation to be used in large-eddy simulations (LES) of turbulent liquid sprays. Effects of small-scale intermittency, usually under-resolved in LES, are explicitly included via modelling of the energy dissipation rate seen by a droplet along its trajectory. Namely, the dissipation rate is linked to the norm of the droplet sub-filtered acceleration which is included in the droplet motion equation. This norm, along with the direction of the droplet sub-filtered acceleration, is simulated as a stochastic process. With increasing Reynolds number, the distribution of the sub-filtered acceleration develops longer tails, with a slower decay in auto-correlation functions of the norm and direction of this acceleration. The stochastic models are specified for particles larger and smaller the Kolmogorov length scale. The assumption of the droplet evaporation model is similar, i.e. the evaporation rate is strongly enhanced when a droplet is subjected to very localized zones of intense velocity gradients. Thereby, the overall evaporation process is assumed to be a succession of two steady-state sub-processes with equal intensities, i.e. evaporation and vapour mixing. Then the stochastic properties of the overall evaporation rate are also controlled by fluctuations of the energy dissipation rate along the droplet path, and with increasing Reynolds number, the intensity of fluctuations of this rate is also increasing. The assessment of the presented stochastic models in LES of high-speed non-evaporating and evaporating sprays show the accurate prediction of experimental data on relatively coarser grids along with a remarkably weaker sensitivity to the grid spacing. The joint statistics and Voronoi tessellations exhibit strong intermittency of evaporation rate. The intensity of turbulence along the droplet pathway substantially promotes the vaporization rate.

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Detailed characteristics of drop-laden mixing layers: Large eddy simulation predictions compared to direct numerical simulation

Cited by 13 publications

References 36 publications

Large-eddy simulations for internal combustion engines – a review

Large-eddy simulations for internal combustion engines – a review

Spray Combustor Design/Performance: Chemical Engineering Contributions and the Emergence of an “Interacting Population-Balance” Perspective

Stochastic models for the droplet motion and evaporation in under-resolved turbulent flows at a large Reynolds number

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