A novel method for simulating smoldering propagation and its application to STAR (Self-sustaining Treatment for Active Remediation)

This work presents the development and proof of concept of a phenomenologically-based numerical model capable of simulating the expansion of a smoldering front in a heterogeneous reactive porous medium. This practical tool has potential for investigating a range of large-scale smoldering phenomena including subsurface peat and coal fires. The model is applied to the smoldering of non-aqueous phase liquids (NAPLs) embedded in soil. NAPLs are industrial chemicals found extensively polluting the subsurface and their in situ destruction via smoldering combustion is a promising site remediation approach referred to as STAR (Self-sustaining Treatment for Active Remediation). The In Situ Smoldering Model was developed through the novel coupling of a multiphase flow simulator with a combustion front expansion model, linked at the local (i.e., nodal) scale by a calibrated expression for the forward smoldering front velocity that is a function of airflow velocity and NAPL content. Numerical testing revealed that the model is computationally efficient and capable of handling two-dimensional smoldering propagation for a range of challenging physical scenarios.