Study Of Wildfire In-draft Flows For
Counter Fire Operations
Author(s)
R. Roxburgh & G. Rein
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.
Keywords: entrainment, fire fighting, suppression, back fire, computer
modelling, CFD, FDS.
1 Introduction
A common method of wildfire suppression is the use of fire breaks to stop the
progress of a flaming front. Fire breaks are strips of land from which all or most
of the flammable materials have been removed [1–3]. These strips create fuelless
barriers past which the wildfire cannot spread as it no longer has fuel. These
can often be incorporated into natural fire barriers such as rivers, canyons and
roads in order to increase their size and effectiveness. The width of a fire break
has to be sufficient large to avoid the flaming ignition across it. A common rule
based on the radiant power states that a fire-break must be one and a half times
as wide as the flame height [2, 3]. One speedy way of creating a fire break is to
light a counter fire a certain distance in front of the main wildfire. Due to the
Keywords
entrainment, fire fighting, suppression, back fire, computer
modelling, CFD, FDS.
Related Book
Other papers in this volume
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