Studies on Fire Spread Over Centrally Ignited Forest Fuel Bed Using Fire Dynamics Simulator

This work reports simulations of flame spread over a square region of forest biomass fuel that is centrally ignited. The dependence of the rate of spread (ROS) of fire on the angle of inclination of the fuel surface with respect to horizontal is studied. Flame spread over the solid fuel surface is modelled using appropriate sub-models for moisture evaporation, pyrolysis of fuel, char oxidation and gas phase combustion in Fire Dynamics Simulator (FDS). The numerical model is able to predict a flame spread rate of 0.279 m/min for the horizontal fuel bed, which compares well with the experimental value reported in the range of 0.17–0.28 m/min. The numerical model is then used to investigate the effect of inclination of the fuel bed with respect to the horizontal, by varying the inclination angle as 30°, 45°, 60°, 75° and 90°. Results show that when the angle of inclination is increased, ROS increases in the upslope direction and decreases in the downslope direction. Along the lateral direction, ROS increases with an increase in the angle of inclination. The fire dynamics are explained using instantaneous contours of temperature and the fields of velocity vectors, for several inclination cases.