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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. [ABSTRACT FROM AUTHOR]

Fire whirls are a particular case of flame behaviour characterized by a rotating column of fire driven by intense convective heating of air close to the ground. They typically result in a substantial increase in burning rate, temperature, and flame height. Fire whirls can occur in any intense flame environment, including urban areas, particularly within combustible structures, and in wildland or forest fires. Recently, investigations on the creation of fire whirls have attracted much attention. However, most analyses are focused on fire whirl structure, formation, and controlling their unique state. In effect, revisiting the available experimental techniques and numerical simulations used in analyzing fire whirls has received less attention. In this paper, experimental arrangements including empirical set ups and employed fuels are presented in detail. Subsequently, major research progress focused on experimental studies and their laboratory setup is fully discussed, followed by the available numerical simulations, including combustion and turbulence models. Applied methodologies and chosen software in the recent numerical studies are also reviewed exclusively. Finally, the latest findings are featured, and prospective pathways are advised. [ABSTRACT FROM AUTHOR]

Detailed investigation of fire-wind interaction is highly instrumental in understanding the cause of the devastating consequences of major fire events in windy weather conditions. Enhancement of wind downstream of the fire source is a phenomenon caused by fire-wind interaction. The main objective of this study is to compare the behavior of wind enhancement for fire of either line or point sources under similar wind and heat release rate conditions. This paper uses the OpenFOAM platform as a numerical simulation tool to fundamentally investigate fire-wind enhancement phenomenon in both point and line source of the fire. A module has been developed and implemented in the FireFOAM solver to extract different components of fire-induced longitudinal and vertical forces. A new parameter expressed as an equivalent hydraulic diameter of line fire sources was introduced to represent the non-dimensional bushfire intensity. The results indicate that under the same intensity of heat release rate per unit area, enhancement of longitudinal wind in line fire is significantly higher than that of the point fire source. On the other hand, the fire-induced vertical velocity of point source fire is higher than that of the line source case. [ABSTRACT FROM AUTHOR]

• The mechanisms involved in fire-wind enhancement phenomenon are investigated. • Fire-wind interaction creates longitudinal negative pressure gradient. • Increase of wind velocity reduces the effects of fire on the flow aerodynamics. • Richardson and modified Euler number are the contributing non-dimensional groups. • Fire-wind enhancement variation depends on Richardson and modified Euler number. Variation in flow characteristics triggered through the fire-wind interface can potentially damage the buildings during bushfires. Fire-wind enhancement which is referred to as the increase of wind velocity, caused by the fire-wind interaction, is one of the destructive phenomena in this regard. In spite of the significance, the underlying mechanism contributing to this phenomenon is still not well understood. This study employs computational fluid dynamic (CFD) simulation to fundamentally investigate the effects of free-stream wind velocity on fire-wind enhancement through analyzing the momentum and buoyancy of fluid. Fire-wind interaction is shown to cause the generation of fire-induced longitudinal negative pressure gradient which results in fire-induced pressure and viscous forces in longitudinal direction. These forces are further found as the prime reason for the distortion of the wind velocity profile. A module is implemented to the FireFOAM solver to calculate and extract these forces quantitatively. The results reveal that under a constant fire intensity, the level of distortion and/or enhancement in the wind velocity profile comparatively reduces with the increase of free-stream wind velocity. A new non-dimensional group (modified Euler number) is introduced to take into account dominant fire-induced forces causing fire-wind enhancement. Richardson number and the modified Euler number are employed to determine the influence of free-stream wind velocity and longitudinal distance from the fire source on wind velocity enhancement. Large-eddy simulation (LES) results indicate that while the level of enhancement generally depends on both Richardson and the modified Euler number, the location of the maximum level of enhancement along the plume centreline coincides with the maximum value of modified Euler number under a constant free-stream wind velocity scenario. [ABSTRACT FROM AUTHOR]