A computational tool for the detailed kinetic modeling of laminar flames: Application to C 2 H 4 /CH 4 coflow flames Alberto Cuoci ⇑ , Alessio Frassoldati, Tiziano Faravelli, Eliseo Ranzi Department of Chemistry, Materials, and Chemical Engineering, Politecnico di Milano, P.zza Leonardo da Vinci 32, 20133 Milano, Italy article info Article history: Received 29 August 2012 Received in revised form 6 December 2012 Accepted 18 January 2013 Available online 16 February 2013 Keywords: Laminar flame Coflow flame Detailed kinetics Operator-splitting method PAH abstract In this work a new computational framework for the modeling of multi-dimensional laminar flames with detailed gas-phase kinetic mechanisms is presented. The proposed approach is based on the operator- splitting technique, in order to exploit the best numerical methods available for the treatment of reacting, stiff processes. The main novelty is represented by the adoption of the open-source OpenFOAM Ò code to manage the spatial discretization of the governing equations on complex geometries. The resulting com- putational framework, called laminarSMOKE, is suitable both for steady-state and unsteady flows and for structured and unstructured meshes. In contrast to other existing codes, it is released as an open-source code and open to the contributions from the combustion community. The code was validated on several steady-state, coflow diffusion flames (fed with H 2 , CH 4 and C 2 H 4 ), widely studied in the literature, both experimentally and computationally. The numerical simulations showed a satisfactory agreement with the experimental data, demonstrating the feasibility and the accu- racy of the suggested methodology. Then, the C 2 H 4 /CH 4 laminar coflow flames experimentally studied by Roesler et al. [J.F. Roesler et al., Combust. Flame 134 (2003) 249–260] were numerically simulated using a detailed kinetic mechanism (with 220 species and 6800 reactions), in order to investigate the effect of methane content on the formation of aromatic hydrocarbons. Model predictions were able to follow the synergistic effect of the addition of methane in ethylene combustion on the formation of benzene (and consequently PAH and soot). Ó 2013 The Combustion Institute. Published by Elsevier Inc. All rights reserved. 1. Introduction Numerical simulations of laminar flames have received a wide- spread interest in the past two decades, since they can be used for the design and optimization of industrial and domestic equipment (e.g. furnaces, domestic gas burners, industrial burners, etc.), and for the understanding and modeling of more complex flows (e.g. turbulent flames). However, the modeling of multi-dimensional laminar flames with realistic chemical mechanisms represents a challenging problem and places severe demands on computational resources, mainly because of the large number of chemical species involved, the high stiffness of the governing equations and the presence of high gradient regions (especially close to the flame front) [1]. When detailed kinetic schemes are used, special atten- tion must be devoted to the numerical algorithms, which must be very efficient and accurate. At the same time, the spatial discret- ization has to be fine enough to adequately describe the flame fronts and the high gradients. Consequently, the computational ef- fort in terms of CPU time and memory requirements is consider- able and often prohibitive. Conventional CFD methods based on segregated algorithms have serious difficulties in treating the stiffness and the high non-linearities of the governing equations and cannot be efficiently applied in this context. In order to overcome these problems, cou- pled methods appear to be an attractive alternative. In particular, among others, two main numerical approaches have been used for the resolution of such a stiff, large system of equations: (i) fully coupled algorithms [2]; (ii) algorithms based on operator-splitting methods [3–7]. An advantage of fully coupled algorithms is that all the processes are considered simultaneously, so all physical inter- actions among processes are taken into account together (and therefore this seems the natural way to treat problems with multi- ple stiff processes). However, the resulting system of governing equations can be extremely large (especially when detailed kinetic mechanisms and complex, multi-dimensional geometries are con- sidered). When operator-splitting methods are used, the governing equations are split in sub-equations, usually with each having a single operator, capturing only a portion of the physics present. Splitting approaches can be conveniently applied for the numerical solution of combustion problems, by separating the stiff chemical 0010-2180/$ - see front matter Ó 2013 The Combustion Institute. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.combustflame.2013.01.011 ⇑ Corresponding author. Fax: +39 02 7063 8173. E-mail address: alberto.cuoci@polimi.it (A. Cuoci). Combustion and Flame 160 (2013) 870–886 Contents lists available at SciVerse ScienceDirect Combustion and Flame journal homepage: www.elsevier.com/locate/combustflame