A COMPUTER ALGORITHM FOR SIMULATING THE SPREAD OF WILDLAND FIRE PERIMETERS FOR HETEROGENEOUS FUEL AND METEOROLOGICAL CONDITIONS

This work describes a computer based technique for simulating the spre ad of wildland fire for heterogeneous fuel and meteorological conditio ns. The mathematical model is in the form of a pair of partial differe ntial equations, and can model fuels whose fire perimeter for homogene ous conditions is any given shape, such as ellipses, double ellipses, lemniscates etc. Provided the fire does not attempt to burn into an al ready burnt out region, then the differential equations are easily sol ved and a simple method of solution is presented. To identify regions that are internal to the fire perimeter an algorithm that uses the tur ning number of a point in the plane relative to the fire perimeter is used. The algorithm is found to be reliable, and allows for the simula tion of highly complex fire scenarios in a reasonable time. Example si mulations are presented that involve variations in fuel, barriers, win d direction changes and multiple fires.