International Journal of Wildland Fire International Journal of Wildland Fire Society
Journal of the International Association of Wildland Fire
RESEARCH ARTICLE

Effects of distribution of bulk density and moisture content on shrub fires

Ambarish Dahale A , Selina Ferguson A , Babak Shotorban A B and Shankar Mahalingam A

A Department of Mechanical and Aerospace Engineering, The University of Alabama in Huntsville, 5000 Technology Drive, Huntsville, AL 35805, USA. Email: ard0004@uah.edu; dovers@uah.edu; shankar.mahalingam@uah.edu

B Corresponding author. Email: babak.shotorban@uah.edu

International Journal of Wildland Fire 22(5) 625-641 https://doi.org/10.1071/WF12040
Submitted: 14 March 2012  Accepted: 13 November 2012   Published: 25 March 2013

Abstract

Formulation of a physics-based model, capable of predicting fire spread through a single elevated crown-like shrub, is described in detail. Predictions from the model, obtained by numerical solutions to governing equations of fluid dynamics, combustion, heat transfer and thermal degradation of solid fuel, are found to be in fairly good agreement with experimental results. In this study we utilise the physics-based model to explore the importance of two parameters – the spatial variation of solid fuel bulk density and the solid fuel moisture content – on the burning of an isolated shrub in quiescent atmosphere. The results suggest that vertical fire spread rate within an isolated shrub and the time to initiate ignition within the crown are two global parameters significantly affected when the spatial variation of the bulk density or the variation of fuel moisture content is taken into account. The amount of fuel burnt is another parameter affected by varying fuel moisture content, especially in the cases of fire propagating through solid fuel with moisture content exceeding 40%. The specific mechanisms responsible for the reduction in propagation speed in the presence of higher bulk densities and moisture content are identified.


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