Analysis of Effects of Stand Density on Wildfire Spread Using Physics-Based Simulation

To analyze the effects of stand density on wildfire spread, physics-based simulations of a flat pine forest were performed while varying tree stand spacing and wind speed. The results from the crown fire transition and subsequent spread stages were collected and analyzed through visual analysis and a comparison of the wildfire spread rates. Overall, strong flame behavior was observed during the transition to a crown fire, which subsequently developed into a quasi-steady propagation. The results indicate that the wildfire spread rate increases with wind speed. Moreover, the optimal stand spacing that maximizes the spread rate was found to depend on the wind speed. This trend is attributed to the balance between the flame intensity driven by the fuel load and the oxygen availability during combustion. Consequently, the maximum spread rate occurs at an optimal stand spacing, similar to the optimal packing ratio effect of surface fire spread models.