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Forest
fires cost the United States millions of dollars
per year in property and land loss and were responsible
for the deaths of numerous firefighters and civilians
last year. In addition, this year, there have been
highly publicized aviation disasters that have occurred
in attempting to extinguish the infernos.
What if the likely ignition locations
of these fires could be predicted? What if the spread
of these fires could be predicted and therefore controlled
before becoming uncontrollable? Unusually for a CFD
challenge this is not about reducing design costs,
nor about meeting production deadlines: it is, however,
about protecting the environment and saving property
and lives where the deadlines are even more critical.
With this in mind, it is no surprise
that the use of advanced analysis tools such as STAR-CD
are being used to help provide an insight into such
a damaging and life threatening phenomenon.
Leading the research and development
of forest fire management are the team of engineers
and scientists at the Forest Service’s Fire
Sciences Laboratory in Missoula, Montana. They have
recently acquired STAR-CD to further advance their
already comprehensive numerical modeling techniques
and gain a better understanding of how to contain
and minimize forest fire spread. Their facility is
equipped with an instrumented wind tunnel burn-rig,
capable of burning a range of solid fuels in a controlled
environment and generating valuable data. The study
of fire growth in the wind tunnel can then be compared
to predictions performed using STAR-CD in an effort
to correlate combustion and turbulence models required
to predict this chaotic flow domain.
On the macro-environment scale,
analyses carried out by the Forest Service using
STAR-CD have involved the study of the flow of large
air masses over topo-graphical domains. Using satellite-based
digital elevation map (DEM) data, the landscape surface
can be read automatically into STAR-CD to provide
an immediate shell representation of the ground surface.
CD-adapco worked together with the Fire Sciences
lab to develop this automated process to build the
computational model based on the DEM data. Once the
boundary conditions have been added, which represent
actual measured wind velocities in both 3-D spatial
and temporal reference frames, the analysis can be
run and results post-processed all within STAR-CD.
The ability of STAR-CD’s
modular framework to interact with third party codes
and in-house software has been a major boost to the
Scientists and Engineers at the Fire Research Center.
Using STAR-CD as the backbone of their computational
effort, the investment in their existing in-house
codes is protected by linking these directly to STAR-CD
to produce a dedicated framework suited to highly
specific problems. This approach is exemplified by
the creation of dedicated user-panels to fully automate
the analysis set-up, execution and post-processing.
Future work will include the analysis
of local buoyancy effects due to fire progression
and also the impact of solar radiation on mountain
slopes, which can act as a catalyst in the spread
of vegetation fire.
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