Numerical study of the interaction between a head fire and a backfire propagating in grassland.

Abstract

One of the objectives of this paper was to simulate numerically the interaction between two line fires ignited in a grassland, on a flat terrain, perpendicularly to the wind direction, in such a way that the two fire fronts (a head fire and a backfire) propagated in opposite directions parallel to the wind. The numerical simulations were conducted in 3-0 using the new fuel element module recently implemented in WFDS. We chose grassland for the fuel layer, because it represents certainly one of the most studied eco-system, in the frame of experimental campaigns to study the behavior of surface fires at large scale. The aim of this numerical study is to understand what are the physical phenomena and the favorable conditions of ignition of a counter fire, during a fire suppression operation. The preliminary results highlighted that the two fire fronts interacted only at a relative short distance (10-20 m). During the last step of the merging of the two fire fronts, a sudden increase of the heat release rate was observed, indicating a significant interaction between the two fires, which can potentially represent a safety problem for people in charge of this kind of operation.

Citation

Morvan, Dominique; Meradji, Sofiane; Mell, William. 2011. Numerical study of the interaction between a head fire and a backfire propagating in grassland. Fire Safety Science. 10: 1415-1424.