Numerical Simulation of Wildfire Spread in Inclined Trenches

The effects of the slope and the trench inclination on the spread of wildfires with a homogeneous fuel bed in inclined trenches, were studied numerically by Fire Dynamics Simulator. This simulation is based on a solid–gas two-phase numerical model that incorporates the physicochemical combustion characteristics of Platycladus orientales leaves. The results show that the rate of fire spread accelerates with increasing slope and trench inclination. The flame front inclines until it attaches to the fuel bed for slope angles ranging from 20.9° to 35.2°, and it was found a critical angle for full attachment is about 35.2° for trench inclination of 45°. Increasing the trench inclination causes a decrease in the critical angle because the trench wall restricts air entrainment at the bottom flame, promoting the flame to adhere to obtain sufficient air. Flame radiation is the dominant heat transfer mechanism at low slopes, and as the slope increases, convective heat transfer starts to be relevant and significantly changes with the trench inclination. This study provides scientific insights and guidance for early prevention and fire fighting in inclined trenches of wildfires.