Combustion and Flame 146 (2006) 29–51 www.elsevier.com/locate/combustﬂame An automatic procedure for the simpliﬁcation of chemical kinetic mechanisms based on CSP Mauro Valorani a , Francesco Creta a , Dimitris A. Goussis b , Jeremiah C. Lee c , Habib N. Najm d,∗ a Dipartimento di Meccanica e Aeronautica, Via Eudossiana 18, 00184 Rome, Italy b Palaio Faliro 17562, Greece c United Technologies Research Center, East Hartford, CT 06108, USA d Sandia National Laboratories, Livermore, CA 94550, USA Received 30 June 2005; received in revised form 21 March 2006; accepted 27 March 2006 Abstract An algorithm is developed to generate simpliﬁed (skeletal) kinetic mechanisms from a given detailed one. The algorithm is able to replicate the dynamics of a user-speciﬁed set of species (chosen from the original set) when a ﬁnite set of sampling points, D, in the chemistry conﬁguration space is given. The simpliﬁcation procedure involves discarding elementary reactions and species that are deemed unimportant to the fast and slow dynamics of a set of speciﬁc scalars. The criteria used in deciding which elementary reactions or species to discard are based on the computational singular perturbation (CSP) method. The procedure involves applying the CSP analysis to each point in D and an algorithm to assemble the simpliﬁed mechanism, the validity of which extends to all points in D and is tailored for the set of speciﬁed scalars. This algorithm provides a convenient way to construct comprehensive simpliﬁed mechanisms, applicable over a wide range of parameters and combustion processes. The effectiveness of this new algorithm is demonstrated by constructing simpliﬁed mechanisms for three methane/air reactive systems: autoignition in a constant-pressure reactor, a premixed ﬂame, and a counterﬂow diffusion ﬂame.  2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved. Keywords: Chemical kinetics reduction; Autoignition; Premixed laminar ﬂames; Counterﬂow diffusion ﬂames; Numerical methods 1. Introduction Detailed chemical kinetic mechanisms for hydro- carbon oxidation can be composed of hundreds of species and thousands of elementary reactions. Ki- netic simulations of perfectly homogeneous systems involving kinetic mechanisms of such complexity can * Corresponding author. E-mail address: hnnajm@sandia.gov (H.N. Najm). now be solved in on the order of seconds on mod- ern CPUs. However, inclusion of even moderately complex detailed chemistry in the numerical simula- tion of reactive ﬂows makes the computational cost extremely difﬁcult to afford. Moreover, obtaining nu- merical solutions of such large kinetic systems is not sufﬁcient for answering the ultimate questions the investigator needs to know in order to exploit the full predictive potential of a numerical simulation. In fact, the investigator, besides quantitative answers re- lated to, say, the prediction of global parameters, such 0010-2180/$ – see front matter  2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.combustﬂame.2006.03.011