Lagrangian Stochastic SGS Model Applied to LES of Evolving Firebrand Transports

The transport and deposition of smoldering particles, known as firebrands, is an important fire spread mechanism in wildland fires. These particles can be transported by the wind over large distances and can ignite secondary fires upon landing. The transport of firebrands by the wind is a complex, multiscale process, which is largely controlled by interactions between the firebrand particles and the atmospheric wind flow. Such complexities require the use of Large Eddy Simulation (LES) models to account for the temporal evolution of turbulence over large scales of space and time. However, filtering of subgrid-scale (SGS) turbulence in LES hinders the accuracy of particle transport models. In this work, we employ a SGS stochastic model into an LES framework and develop a model to account for and investigate the effects of small-scale (~ O(particles)) turbulence on the transport of mass- and size-changing firebrand particles. This approach will improve the accuracy of firebrand behavior modeling and spot fire prediction.