Abstract
This paper presents a simplest model that describes the smoldering propagation over a thin solid in a narrow space. A two-equation model is derived based on phenomenological arguments. The Lewis number, defined as the ratio of the solid thermal diffusivity to the oxygen diffusion coefficient, is identified as an important parameter. Numerical solutions of the basic equations exhibit similar finger-like patterns to those observed by previous experiments. The Lewis number effects on smoldering behaviors are discussed.
