The effect of downslope terrain on wildfire dynamics in the presence of a cubic structure

Abstract

In the current work, a numerical study is performed to investigate the effect on the downslope field by a wind driven surface fire in the presence of an idealised building structure. Fires burning with an intensity of 15 MW/m on inclined terrain with various downslope angles of 0, -10, -20, and -30°, and under a constant wind speed of 12 m/s are simulated using a large eddy simulation (LES) solver, implemented in open-source platform FireFOAM. The results are validated with experimental measurements of a full-scale cubic building model. The presented outcomes highlight the physical effect of sloped terrain on a building in the vicinity of a line-fire. The results show that at a constant fire intensity and wind speed, an increase in downslope angle leads to an increase in the surface temperature of the structure downstream of the fire source. In addition, it is shown that increasing the downslope angle from 0˚ to -30°, results in a reduction of the average air density around the structure downstream of the fire. Furthermore, by increasing the downslope inclination of the terrain from 0˚ to -30° increases the average temperature of the building surface by 30%, and increases the temperature of zone downstream of the fire by 9%.