Computational study of the multidimensional spread of smouldering combustion at different peat conditions

Smouldering combustion is the slow, low-temperature, flameless burning of porous fuels, which propagate both laterally and in-depth. In this study, we build a physics-based two-dimensional model to simulate lateral and in-depth smouldering spread simultaneously based on open-source code Gpyro. We first validate the model against a shallow-reactor experiment (of 1.6 cm thickness) in the literature. Based on the validated model, we then investigate 2D smouldering in a 3 times deeper peat layer at different soil conditions. We found that lateral and in-depth spread rates depend on the organic density and the Oxygen supply. Because of the larger Oxygen supply close to the free surface, the lateral spread is 10 times faster than in-depth spread. In addition, for lateral spread the influence of inorganic density and moisture can be explained by a unified parameter, heat sink density, agreeing with previous experimental results. The model predicts the effects of peat conditions on multidimensional smouldering spread and reveals the controlling mechanisms both lateral and in-depth spread, providing a better understanding of this complex phenomenon.