Study of wildfire in-draft flows for counter fire operations

Abstract

The use of counter-fires to gain control over wildfires is a technique used by some fire services around the world. A fire is purposely lighten ahead of the wildfire and the buoyancy induced in-drafts pull it towards the flame front thus creating a fire break of burnt fuel. Well used, this technique is fast, effective and safe. However, no technical research has been done on the subject. Without understanding of the mechanisms, counter-firing remains a difficult technique and can lead to unnecessary risks being taken or opportunities lost. This paper uses computational fluid dynamics to study the in-draft created around wildfires. A generalized structure of the in-draft velocity profile composed of three zones is observed. The length of the different zones are analysed to find the dependence with fire intensity and wind velocity.

A Review of Fire Interactions and Mass Fires

“…Note, however, that the velocity of the flow inside the plume decreases with height, so at some point near the top of the plume no further air is entrained (no velocity difference). Current research on the indraft caused by entrainment as related to fire interactions is focused mainly providing better quantitative predictions with CFD modeling [93,124]. However, plumes from wildfires can interact with local meteorology [125] such as wind and atmospheric conditions.…”

Interaction between head fire and backfire in grasslands

“…A numerical study in 2D (using FDS) was proposed by Roxburgh and Rein [11], to calculate the flow field observed around a wildfire. In this study the fire front was represented as a fixed burner on a bare flat terrain, the fire intensities ranged between 1 and 10 MW/m.…”

A Temporal Framework of Large Wildfire Suppression in Practice, a Qualitative Descriptive Study

“…Of all the activities and tasks that we identified, the size and scope of the burning operations have the greatest significance for future suppression research. Recent technical literature on burning operations is limited to a small number of numerical simulations of suppression burning [83][84][85]. The experimental work of Wilson [86], which derived an equation for the width of a firebreak required to stop a grassfire, noted that in practice, burning operations would be important, but they were not included in Wilson's experiment.…”