  Smoldering combustion plays an important role in forest and wildland fires.
Fires from smoldering combustion can last for long periods of time, emit more
pollutants, and be difficult to extinguish. This makes the study of smoldering
in woody fuels and forest duff important. Cellulose, hemicellulose, and lignin
are the major constituents in these type of fuels, in different proportions for
different fuels. In this paper, we developed a 1-D model using the open-source
software Gpyro to study the smoldering combustion of cellulose and
hemicellulose mixtures. We first validated our simulations against
experimentally obtained values of propagation speed for mixtures with fuel
compositions including 100%, 75%, 50%, and 25% cellulose, with the remaining
proportion of hemicellulose. Then, we studied the effects of varying fuel
composition, density, and moisture content on smoldering combustion. We find
that propagation speed of smoldering increased with decreases in density and
increases in hemicellulose content, which we attribute to the role of oxygen
diffusion. Propagation speed increased with moisture content for pure cellulose
up to a certain limiting value, after which the propagation speed dropped by up
to 70%. The mean peak temperature of smoldering increased with increases in
hemicellulose content and density, and decreased with increasing moisture
content.
