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Fire Simulation with Dry Eucalyptus & Flat Terrain

In the past, studies and numerical simulation of forest fires have treated the fire-atmosphere as an uncoupled system. The simulation we show here from 1997 is particulary interesting because a simple, dry-eucalyptus fire model is fully coupled with an atmospheric model to conduct the study. Both ground and canopy fuels are prescribed as are winds, which are forced in a hyperbolic-tangent profile, with 3 m/s at surface and -3 m/s at top of the domain which is 1 km.
         

Buoyancy, Iso=.2, Frontview

 

Buoyancy, Volume, Frontview

 

Buoyancy, volume-rendered with particle advection

Buoyancy, Iso=.2, Frontview

QuickTime | Real | MPEG

Buoyancy is the difference between model and ambient temperature. Isosurfaces are shown in red. This field shows the general shape of the temperature gradients in the simulation. Note the evolution of the curved shape of the fire line.

  Buoyancy, Volume Visualization, Frontview

QuickTime | Real | MPEG

The volume visualization represents the buoyancy field, not the fire itself, even though it looks like the fire.

 

QuickTime | Real | MPEG

Lofted burning particles were examined to see if they might be tossed out in front of the fire, thus participating in the propagation of the event.

         
         

Vorticity, Iso=+/-.2, Frontview

 

Vertical Vorticity, Isosurfaces, Frontview

   

Vorticity, Iso=+/-.2, Frontview

QuickTime | Real | MPEG

 

Vertical Velocity, Isosurfaces, Frontview

QuickTime | Real | MPEG

The vertical vorticity field is basically a measure of the rotation about the vertical axis, and provides a good rendering of the two counter-rotating vortices that appear on each edge of the fire late in the simulation. Such behaviour is often observed in naturally occuring fires. In this simulation, these vortices approach tornadic strength.

   
         

Abstract from Clark, Coen, et al paper:

Related Links
 


  Fire Simulation with Hill

  Fire Shape, Whirls & Bursts

  Big Elk Fire Simulation

  MetEd Fire Weather Training Modules

 
 

"A numerical atmospheric model is coupled with a simple dry eucalyptus forest fire model to create a wildfire simulation model. This is used to show how certain atmospheric conditions can lead to commonly observed forest fire behaviour. Using short line fires, simulations show that with moderate winds, the fire line interacts with the updraft ahead of it causing the fire line to curve forward into a conical shape. Other experiments show that when ambient winds change with height, a pair of rotating updrafts at the curved fire front can touch down within the fire and break up the fire line. We also demonstrate "dynamic fingering", in which the rotating columns near the fire front intensify to tornado strenth and can result in rapid and strong increases in the fire spread rate."

   
   
Model  
Model Name:
Clark Fire Model, FR7CS1
Data  
Time Resolution:
5 seconds
Timesteps:
336
Domain  
Horizontal Real World:
1 x 1 km
Vertical Real World:
1 km
Horizontal Resolution:
60 x 60
Vertical Resolution:
26
Visualization  
Visualization:
Don Middleton
Software:
Vis5D with enhancements to support particles
Hardware:
Onyx
CPU Time:
~ 1 day
Project
Scientists:
Terry Clark
Janice Coen
Date Created:
1997
Date Catalogued:
2002-08-05
Rights:
© 2002, UCAR, All rights reserved.