Journal ArticleDOI
A simple model for the filtered density function for passive scalar combustion LES
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In this paper, the authors proposed a top-hat distribution for turbulent non-premixed combustion models, which is an alternative to the β function for RANS applications, and tested a posteriori for a piloted diffusion flame (Sandia Flame D).Abstract:
LES models for turbulent non-premixed combustion usually require knowledge of the filtered density function of the conserved scalar, and we propose to use a simple top-hat function. Such top-hat distributions were developed as probability density functions for RANS applications in the 1970s but were soon surpassed by the β function. We find that in the context of LES, the top-hat distribution provides an excellent alternative to the now much more common β function. The top-hat function is assessed through a phenomenological analysis of Direct Numerical Simulation (DNS) data from a planar jet and of experimental data from a turbulent opposed jet. The approach is then tested a posteriori for a piloted diffusion flame (Sandia Flame D). Advantages of the top-hat function are the ease of implementation and the reduced dimensionality of look-up tables. The present paper also discusses inconsistencies of sub-grid β-FDFs, the FDFs sensitivity on implicit filtering, and the regime in which a β assumption can be a ...read more
Citations
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Journal ArticleDOI
From Large-Eddy Simulation to Direct Numerical Simulation of a lean premixed swirl flame: Filtered laminar flame-PDF modeling
TL;DR: In this paper, a large-scale simulation of a swirl burner operated with a lean methane-air mixture and experimentally studied by Meier et al. is performed for various mesh refinements, to study unsteady and coherent large scale behavior and validate the simulation tool from measurements.
Journal ArticleDOI
State-of-the-art in premixed combustion modeling using flamelet generated manifolds
van Ja Jeroen Oijen,A Andrea Donini,Rjm Rob Bastiaans,ten Jhm Jan Thije Boonkkamp,de Lph Philip Goey +4 more
TL;DR: In this paper, the generalized flamelet model is used for the modeling of premixed and partially-premixed flames, and the results compare well with numerical results for flames with thin reaction layers, but described by multiple-species transport and chemistry.
Journal Article
Large eddy simulation of a nonpremixed reacting jet: Application and assessment of subgrid-scale combustion models
TL;DR: In this paper, the results from large eddy simulations (LES) and direct numerical simulations (DNS) of a two-dimensional, spatially developing, compressible planar free jet undergoing an idealized, exothermic, chemical reaction of the type F+rOx→(1+r)P are presented in order to assess several subgrid-scale combustion models.
Journal ArticleDOI
Towards Comprehensive Coal Combustion Modelling for LES
Oliver T. Stein,G. Olenik,Andreas Kronenburg,F. Cavallo Marincola,B.M. Franchetti,Andreas M. Kempf,M. Ghiani,M. Ghiani,M. Vascellari,Christian Hasse +9 more
TL;DR: In this paper, large eddy simulations of pulverised coal combustion (PCC-LES) stabilised on a laboratory-scale piloted jet burner are carried out, and the details of the comprehensive coal combustion models and their numerical implementation in three different computer programs are discussed.
References
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General circulation experiments with the primitive equations
TL;DR: In this article, an extended period numerical integration of a baroclinic primitive equation model has been made for the simulation and the study of the dynamics of the atmosphere's general circulation, and the solution corresponding to external gravitational propagation is filtered by requiring the vertically integrated divergence to vanish identically.
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A dynamic subgrid‐scale eddy viscosity model
TL;DR: In this article, a new eddy viscosity model is presented which alleviates many of the drawbacks of the existing subgrid-scale stress models, such as the inability to represent correctly with a single universal constant different turbulent fields in rotating or sheared flows, near solid walls, or in transitional regimes.
Journal ArticleDOI
Laminar diffusion flamelet models in non-premixed turbulent combustion
TL;DR: In this paper, the steady laminar counterflow diffusion flame exhibits a very similar scalar structure as unsteady distorted mixing layers in a turbulent flow field, and the conserved scalar model is interpreted as the most basic flamelet structure.
Book
Computational Models for Turbulent Reacting Flows
TL;DR: In this article, the authors present the current state of the art in computational models for turbulent reacting flows, and analyzes carefully the strengths and weaknesses of the various techniques described The focus is on formulation of practical models as opposed to numerical issues arising from their solution A theoretical framework based on the one-point, one-time joint probability density function (PDF) is developed.