The use of prescribed fire is essential to land management of Department of Defense (DoD) installations. The planning of such fires requires the assessment of their safety and potential negative impacts to air quality and visibility in communities and road systems downwind of prescribed fires. Smoke dispersion models that have traditionally been used in this assessment are designed to predict large-scale (long range) smoke transport. The modeling of near-fire processes and features, such as the fire-atmosphere interaction and near-fire plume rise, is oversimplified, leading to inadequate predictions of local smoke conditions. As an alternative, newer physics-based coupled fire-atmosphere models that have been tested and refined in the past decade offer improved ability to simulate the local processes with much higher physical fidelity. However, using these models requires specialized knowledge and significant computational resources that exceed those of most fire management agencies. As a compromise, simplified versions of these models have been developed to enhance usability, but they remain relatively untested. The physics based Fire Dynamics Simulator (FDS), which was developed by the U.S. National Institute of Standards and Technology, is one such model. Thus, the objective of this project is to investigate the practicality of applying a simplified version of FDS to predict the evolution of wildland fire fronts, fire-atmosphere interactions, and the resulting near fire smoke plume development for the purpose of planning prescribed burns of interest to the DoD.

The project team will assess the capability of the FDS-Level Set, a simplified form of the physics-based coupled fire – atmospheric model FDS-Physics Based, as well as simplified models of nearfield smoke transport, to capture the development of buoyant smoke plume(s) and dynamic fire behavior during prescribed burns. This assessment will be conducted through comparison with the higher fidelity model (FDS-PB). In collaboration with burn practitioners, model testing scenarios will be developed, against which the different modeling approaches can be tested. Model evaluations will also make use of observational data of fire progression and smoke plume dynamics from a number of SERDP and Joint Fire Science Program funded experimental burn projects, potentially including the Fire and Smoke Modeling Evaluation Experiments.

This project will assess the capability of reduced-physics models of wildland fire, as compared to full-physics models, to represent coupled fire spread and smoke plume evolution. Scientific understanding will be advanced by identifying, in the scenarios to be examined, model parameters and scales essential and non-essential to preserving the predictions of the full-physics simulations. This understanding, in turn, will guide future development and deployment of improved software tools for the planning of prescribed fires for management of DoD lands. (Anticipated Project Completion - 2026)