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Effects of Winds From Burning Structures on Ground-Fire Propagation at the Wildland-Urban Interface.


pdf icon Effects of Winds From Burning Structures on Ground-Fire Propagation at the Wildland-Urban Interface. (2394 K)
Rehm, R. G.

Combustion Theory and Modelling, Vol. 12, No. 3, 477-496, June 2008.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD

Keywords:

wildland urban interface; wind effects; structures; combustion; flame propagation; heterogeneous burning; mathematical models; fire spread; fire models; fire behavior; heat release rate; plumes; scaling; wildland fires; equations; computational fluid dynamics; grasslands

Abstract:

A simple physics-based mathematical model is developed for prediction of the propagation of a grass-fire front driven by an ambient wind and by entrainment winds generated from one or more burning structures. This model accounts for the heterogeneous nature of the burning in a particular wildland-urban-interface (WUI) setting, where the entrainment from fundamentally three-dimensional structure-fire plumes can change the propagation of a two-dimensional ground-fire front. Data on grass fires and estimates of structure fires are presented and compared to justify the model. Scaling effects on the fire-front propagation-speed are given as a function of the location of the front, of the heat release rate of a single burning structure, of the total number of burning structures and of the burning-structure density. Also, detailed front propagation changes due to a single and multiple burning-house scenarios are presented.