Numerical Simulation of the Effect of Fire Intensity on Wind Driven Surface Fire and Its Impact on an Idealized Building

Ali Edalati-nejad,Maryam Ghodrat,Albert Simeoni,Sayyed Aboozar Fanaee

doi:10.3390/fire5010017

Ali Edalati-nejad, Maryam Ghodrat + Show 2 more

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https://doi.org/10.3390/fire5010017

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Abstract

This paper presents an investigation on the effect of fire intensity of a wind driven surface fire, similar to a large wildfire, on an idealized structure located downstream from the fire source. A numerical simulation was conducted using an open source CFD code called FireFOAM, which is a transient solver for fire simulation and turbulent diffusion flames, supported by a large eddy simulation (LES) solver for incompressible flow. The numerical data were verified using the aerodynamic experimental data of a full-scale building model with no fire effects. An idealized cubic obstacle representing a simplified building with the dimension of 6 × 6 × 6 m; is considered downstream from the fire source. Different fire intensity values of the fire line representing different grassland fuels were simulated to analyse the impact of wind-fire interaction on a built area. To solve the problem, a coupled velocity and pressure method was applied through a PIMPLE scheme in FireFoam solver of OpenFoam platform. There is a good agreement between simulated results and experimental measurements with a maximum error of 18%, which confirms the validity and accuracy of the model. The results showed that by increasing the fire intensity; the velocity of the crosswind stream increases, which causes low-density air and generates an extra stream behind the fire plume. It was also found that increasing fire intensity from 10 MW/m to 18 MW/m raises the integrated temperature on the ground near the building and on the surface of the building by 26%, and 69%, respectively.

Highlights

The wildland-urban interface (WUI) is not a new matter, fires in WUI communities have suddenly increased in frequency [1]
Wildfire management at the wildland-urban interface (WUI) is becoming more challenging due to expanding development of human inhabitation and sharp growth of land use. This creates substantial wildfire risk to households located at these areas, as combustible grasslands are susceptible to encounter infrastructure
The key point in understanding the problem and finding an appropriate solution is to deal with the aerodynamic behaviour of the flow around the built area, the rate of spread of the fire and its relation to fuel which is directly linked with the intensity of the fire

Summary

Introduction

The wildland-urban interface (WUI) is not a new matter, fires in WUI communities have suddenly increased in frequency [1]. Wildfire management at the wildland-urban interface (WUI) is becoming more challenging due to expanding development of human inhabitation and sharp growth of land use This creates substantial wildfire risk to households located at these areas, as combustible grasslands are susceptible to encounter infrastructure. The key point in understanding the problem and finding an appropriate solution is to deal with the aerodynamic behaviour of the flow around the built area, the rate of spread of the fire and its relation to fuel which is directly linked with the intensity of the fire All such parameters, more or less, play a role in alleviating the impacts of wind driven wildfires on the wildland-urban interface secretions

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