A Multiscale Study of the Coupling Between Flow, Fire and Vegetation – Influence of Vegetation Distribution and Flow on Fire Behavior and Plume Development for Risk Mitigation in Prescribed Burns
Albert Simeoni | Worcester Polytechnic Institute
This project will respond to the first and third research objectives of the Statement of Needs: “Improve understanding of physical fire processes at spatial and temporal scales relevant to plume dynamics, fire behavior, and spotting” and “Advance understanding of fuel dynamics and structure, especially fuel moisture dynamics and the importance of fuel heterogeneity as it relates to fire intensity, ember production, emissions, and crown fire,” respectively. The specific objectives of the project will be to understand how the variability of vegetation influences fire behavior and plume development at multiple scales through drag and heat transfer. Several experiments will be conducted from the small laboratory scale to the large field scale in order to capture the feedback effects between vegetation, flow, fire and plume development. Then, this understanding will be used to test and improve computational fluid dynamics (CFD)-based fire spread models. The project aims at developing a combined experimental and numerical platform that will extend the value of field data by completing the experiments by simulations that can systematically vary the critical parameters that influence fire and plume development.
To advance the knowledge on the coupling between vegetation heterogeneity, fire behavior and plume development, a multi-scale approach will be adopted. The approach will allow deconstructing the complex coupled effects in the laboratory before putting them back together in the field. Static and dynamic experiments will be conducted at the small-, large- and field-scales to investigate more and more complex and realistic coupling between vegetation, fire and plume. Small-scale experiments will be conducted using the Wildfire Exposure Ignition Response Device (WEIRD) platform in Edinburgh, plume and fire-spread experiments will be conducted in Worcester Polytechnic Institute's (WPI)’s large laboratory, and static and dynamic experiments will be conducted in the field at Tall Timbers. The quantified interactions will be then integrated in stages of increasing scale and complexity in two CFD-based fire spread models: Wildland-Urban Fire Dynamics Simulator (WFDS) and FIRETEC. This will ensure that the coupling is well represented, increasing the models’ capacity to capture a wide range of prescribed-burn conditions. The work will focus on describing the interactions between the flow (buoyancy and wind), the vegetation and the fire and will not cover ember production and spotting. However, any spotting occurrence observed in the field experiments will be reported in the results.
This work will increase the science basis for the development of decision support tools for managers to help them decide when and how they can conduct their prescribed burns in order to better reach their objectives, mitigate risks, and manage emissions to the benefit of ecosystems and the population.