On the interaction of wind, fire intensity and downslope terrain with implications for building standards in wildfire-prone areas

Abstract

Background. Wildfires can have detrimental impacts on the environment and urban structures when they spread from wildland areas. Aims. In this work, a numerical study was performed to investigate the effect of downslope terrain on fire-induced flows in the presence of a building structure. Fires with intensities of 4 and 15 MW m−1 were considered on inclined terrain with downslope angles varying from 0° to −30°, and wind speeds of 6 and 12 m s−1. Methods. Simulations were conducted using a large eddy simulation (LES) solver, implemented in the open-source platform FireFOAM. Key results. The results were validated with experimental measurements of a full-scale building model. Results show that at a wind velocity of 12 m s−1, structures on steeper downslope terrains are at higher risk of wildfire damage, whereas at a constant wind velocity of 6 m s−1, these structures are at a lower risk. Conclusions. The outcomes of the study highlight the physical effect of sloped terrain on buildings downwind of a line fire. Implications. The results from this study can be used to evaluate the validity of risk management measures including building standards and asset protection zones and can better inform ways of improving these measures.