Numerical simulation of wind-driven shrubland-fire spread: a parametric study

Background Understanding wildfire dynamics is crucial for effective management and prediction. Aims This study aims to explore the relationship between the rate of fire spread, wind speed and Byram’s convective number (NC) in wind-driven shrubland fires. Methods A parametric study was conducted using FireStar3D, a physics-based wildfire computational fluid dynamics (CFD) model, involving 76 simulations with varying wind speeds, fuel cover-heights, fuel volume-fractions and moisture contents. Key results Findings indicate that the rate of spread (ROS) scales consistently with wind speed, supporting the 10% rule of thumb. While NC inherently includes wind speed, fuel moisture and height effects, fuel volume-fraction significantly influences the ROS through its impact on convective heat transfer. The fire establishment phase was also studied, revealing that fire spreads slightly faster in this phase compared to steady-state, with its duration being a weak function of Byram’s number but strongly correlated to fuel volume-fraction. Conclusions The study yields a better understanding of the relationship between the ROS and NC, it also highlights the role of fuel volume-fraction in fire dynamics and spread rates. Implications These insights enhance our understanding of fire behavior, informing better wildfire management strategies and improving predictive models.