RESEARCH SUMMARY 



Predicting fire behavior in nonuniform fuel arrays is a problem 

 requiring : 



1. A method of assessing fuel nonuniformity, 



2. A method of simulating fuel nonuniformity, and 



3. An algorithm governing fire spread through a simulated array. 



Satisfying these requirements is the objective of this paper. The main 

 concept is built around partitioning the fuel into a honeycomb array. 

 Each cell is described independently according to its bulk fuel para- 

 meters (depth, load, average particle size, etc.). Field assessment is 

 designed to meet the requirements of simulation. An algorithm simulates 

 fire spread through the array by coupling predictions of heat flowing 

 from a burning cell to predictions of the heat required for ignition of 

 the adjacent cells. Ignition is allocated to the cell offering the least 

 requirement for heat. Consequently, the fire moves nonuniformly through 

 the array taking advantage of the path of least resistance. Methodology 

 is emphasized. 



A simulated fire is initiated from a line source. Distortions in 

 the propagating front result from fuel nonuniformities giving rise to a 

 distribution of rates of spread rather than a single value. Analysis 

 is appropriate for an assessment of a distribution of the fireline 

 intensities . 



Examples are given for slash, residue after tree harvest, and a 

 mixture of grass and sagebrush. Nominal windspeeds of and 2 mi/h 

 were chosen for the purpose of illustrating the technique for handling 

 nonuniformity. 



Comparisons show that the previous alternative of combining all 

 fuel to an average depth and load does not allow the land manager to 

 assess the chance that patches of high risk fuel arrangements might 

 result in unacceptable fire behavior. 



