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

Ali Edalati-nejad; Maryam Ghodrat; Jason J. Sharples

doi:10.1071/WF22124

RESEARCH ARTICLE (Open Access)

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

Ali Edalati-nejad

^A , Maryam Ghodrat

^B ^* and Jason J. Sharples

^A ^*

+ Author Affiliations

- Author Affiliations

^A School of Science, UNSW Canberra, Canberra, ACT 2612, Australia. Email: a.edalatinejad@unsw.edu.au

^B School of Engineering and Information Technology, UNSW Canberra, Canberra, ACT 2612, Australia.

^* Correspondence to: m.ghodart@unsw.edu.au, j.sharples@adfa.edu.au

International Journal of Wildland Fire 32(11) 1619-1632 https://doi.org/10.1071/WF22124

Submitted: 4 July 2022 Accepted: 29 June 2023 Published: 3 August 2023

© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of IAWF. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

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.

Keywords: CFD, computational fluid dynamics, downslope, LES, large-eddy simulation, terrain slope, wildfire, wildland–urban interface, wind structure, wind–fire interaction.

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