Using periodic line fires to gain a new perspective on multi-dimensional aspects of forward fire spread

► Three-dimensional variation in wildfire behavior. ► Fire spread rate variation for different line geometry. ► Fire behavior differences for varying wind speeds. This study was conducted to increase understanding of possible roles and importance of local three-dimensionality in the forward spread o...

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Bibliographic Details
Published in:Agricultural and forest meteorology Vol. 157; pp. 60 - 76
Main Authors: Linn, R.R., Canfield, J.M., Cunningham, P., Edminster, C., Dupuy, J.-L., Pimont, F.
Format: Journal Article
Language:English
Published: Amsterdam Elsevier B.V 15-05-2012
Elsevier
Elsevier Masson
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Summary:► Three-dimensional variation in wildfire behavior. ► Fire spread rate variation for different line geometry. ► Fire behavior differences for varying wind speeds. This study was conducted to increase understanding of possible roles and importance of local three-dimensionality in the forward spread of wildfire models. A suite of simulations was performed using a coupled atmosphere–fire model, HIGRAD/FIRETEC, consisting of different scenarios that varied in domain width and boundary condition implementation. A subset of the simulations was strictly two-dimensional in the streamwise and vertical directions, while another subset of simulations involved igniting a finite-length fireline. The remaining simulations were all three-dimensional and employed periodic boundary conditions in the cross-stream direction and a fireline spanning the entire cross-stream extent of the domain. The three-dimensional periodic simulations were compared with the two-dimensional simulations, and then briefly with the finite-length fireline simulations. The two-dimensional scenarios were constrained in their ability to represent inherently three-dimensional physical phenomena such as horizontal flow penetrating through the fireline between plumes of rising hot gas, and cross-stream heterogeneity in the windfield. Elimination of these three-dimensional flow patterns in two-dimensional simulations resulted in over prediction of spread rates in low velocity situations and under predicted spread rates in high wind speed scenarios. In the three-dimensional simulations, local cross-stream heterogeneities in temperature and velocities lead to penetration of hot gases through the fireline and onto unburned fuel. Three-dimensional fires presented a positive correlation between increasing ambient wind speed and rate of spread. Further investigation of finite length fires is required in order to understand the ramifications of fireline curvature.
Bibliography:http://dx.doi.org/10.1016/j.agrformet.2012.01.014
ISSN:0168-1923
1873-2240
DOI:10.1016/j.agrformet.2012.01.014