[LINK] Bush Fire Speeds (was Re: home emergencies)

[Antony Barry]

On 20/02/2009, at 2:22 PM, Brendan Scott wrote:

> The equation would be something to do with the black body  
> temperature of the fire front, the square of the distance from the  
> front, and the specific heat of the flammable materials in the line  
> of sight.


You might not be working with an inverse square law. The firefront is  
approximately linear. Any point in front of the fire is getting heat  
from each point in the front - directly in front and more distant.  
You need to integrate across the firefront to find the contribution.  
My completely rusted up calculus suggested plain inverse rather than  
square in the fire vicinity.

Then there would be hot spots where the fire front was curved,  
running round a depression for instance. After the Canberra fires  
there was a depression near the Tuggeranong Parkway. Outside the  
depression tree trunks survived. Inside there was nothing. The heat  
was focussed into the area.

Tony


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