In filtration combustion, an exothermic reaction wave propagates in a porous medium through which there is gas filtration. Filtration combustion of carbon, for example, is used in various industrial processes such as underground coal gasification, in situ combustion for residual oil recovery, roasting and sintering of ores, blast furnace, and direct reduction of iron from beneficiated iron ores. A previous stability analysis found that there is a cellular solution to the Saffman-Taylor formulation, where mass diffusion is destabilizing. Insights into stability conditions are important for designing industrial processes, and numerical simulations are often conducted. The numerical models generally rely on certain assumptions, and their validity must be tested before using them. However, the 3-D nature of filtration combustion makes comparison between experimental data and numerical predictions difficult; detailed experimental observation requires sensing inside a porous medium, while 3-D numerical simulations are computationally expensive. This paper considers smoldering combustion of a thin paper in a narrow channel, which has been studied in the context of fire safety, and the governing equations are similar to filtration combustion. Since the phenomenon is essentially 2-D, comparison between experimental observations and numerical predictions is straightforward, enabling a simple check of the model assumptions.
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