Computational study on the glowing combustion of a wooden ember landing on a non-reacting substrate

Despite the increasing frequency in spot ignition by embers in wildfires, research on the multiple physicochemical processes intrinsic to ember combustion is limited. In this study, a two-dimensional computational model was proposed to study the glowing combustion of a wooden ember. A global char oxidation reaction was used to represent the glowing combustion of the ember. A parametric study showed that the porosity, heat of reaction, and oxygen concentration were the most influential parameters on the ember combustion. Then, the model was compared to a series of bench-scale experiments in terms of glowing time and thermal response of a non-reacting substrate when exposed to a hot ember. The simulation results showed that ember combustion was mostly diffusion-controlled rather than kinetic-controlled. Thus, given the ember diversities in spotting fire, modelers should pay more attention to the difference in the physical properties instead of the kinetics between ember species.