Numerical Investigation of the Effect of Sloped Terrain on Wind-Driven Surface Fire and Its Impact on Idealized Structures

Ali Edalati-Nejad,Maryam Ghodrat,Albert Simeoni

doi:10.3390/fire4040094

Ali Edalati-Nejad, Maryam Ghodrat + Show 1 more

Open Access

https://doi.org/10.3390/fire4040094

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Abstract

In this study, a time-dependent investigation has been conducted to numerically analyze the impact of wind-driven surface fire on an obstacle located on sloped terrain downstream of the fire source. Inclined field with different upslope terrain angles of 0, 10, 20, and 30° at various wind-velocities have been simulated by FireFoam, which is a large eddy simulation (LES) solver of the OpenFOAM platform. The numerical data have been validated using the aerodynamic measurements of a full-scale building model in the absence of fire effects. The results underlined the physical phenomena contributing to the impact of varying wind flow and terrain slope near the fire bed on a built area. The findings indicated that under a constant heat release rate and upstream wind velocity, increasing the upslope terrain angle leads to an increase in the higher temperature areas on the ground near the building. It is also found that raising the inclined terrain slope angle from 0 to 30°, results in an increase in the integrated temperature on the surface of the building. Furthermore, by raising the terrain slope from 0 to 30°, the integrated temperature on the ground for the mentioned cases increases by 16%, 10%, and 13%, respectively.

Highlights

Bushfires are inevitable natural disasters which have enormous negative environmental and economic impacts
The results revealed that the rate of spread is enhanced with terrain slope for up-hill propagation
As can be seen in this Figure, by increasincreasing the terrain slope, the flame tilt angle caused by buoyancy force increases, and the ing the terrain slope, flamegoes tilt angle caused by buoyancy force increases, the temtemperature near the the building up

Summary

Introduction

Bushfires are inevitable natural disasters which have enormous negative environmental and economic impacts. It is reported that terrain slope has major contributions on the rate of spread of the fire in the inclined fields [6,7,8]. Terrain slope is a crucial element in fire behavior [9], including the rate of spread [10] due to the complex interaction between wind and fire in inclined and complex terrains [11]. Another major challenge in understanding wildfire behavior and fire spread rate is wind and the anomaly of its interaction with fire [12]. It is reported that in windward inclined terrain, air flow acceleration leads to greater fire propagation [15,16]

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Conclusion