Study of the Effect of Fuel Bed Thickness on Surface Fire Spread using Physics-based Simulation

This study analyzes surface fire spread under varying fuel thickness and wind speed using a physics-based simulation.A small wind tunnel experiment was conducted to validate the simulation, and the predicted flame spread rate showed less than 15% error compared with the experimental results.To overcome the limitations of the wind tunnel experiment, including wall effects and limited fuel load per unit length, additional simulations were configured to represent unretarded flame spread.Parametric simulations were performed by varying fuel bed thickness, bulk fuel density, and wind speed.The results indicate that the flame spread rate decreases with increasing bulk fuel density due to reduced oxygen availability and increased heat absorption.Furthermore, the spread rate converges beyond a certain fuel bed thickness, indicating the existence of an effective burning depth.These results highlight limitations of empirical wildfire spread models and provide insights for improving wildfire spread prediction.