A novel computational model of smoldering combustion capable of predicting both forward and
opposed propagation is developed. This is accomplished by considering the one-dimensional, transient,
governing equations for smoldering combustion in a porous fuel accounting for improved chemical
kinetics. The heterogeneous chemistry is modeled with a 5-step mechanism for polyurethane foam. The
kinetic parameters for this mechanism were obtained from thermogravimetric data in the literature and
reported by the authors elsewhere. The results from previously conducted microgravity experiments with
flexible polyurethane foam are used for calibration and testing of the numerical results. Both forward and
opposed smoldering configurations are examined. By considering the 5-step mechanism, the numerical
model is able to predict qualitatively and quantitatively the smoldering behavior, reproducing the most
important features of the process. Specifically, the model predicts the transient temperature profiles, the
overall structure of the reaction-front, the onset of smoldering ignition, and the propagation rate. The fact
that it is possible to predict the experimental observations in both opposed and forward propagation with
a single model is a significant improvement in the development of numerical models of smoldering
combustion. This is particularly relevant in multidimensional simulations where distinction between
forward and opposed modes is no longer applicable
