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Proc Natl Acad Sci U S A. 2015 Aug 11;112(32):9833-8. doi: 10.1073/pnas.1504498112. Epub 2015 Jul 16.

Role of buoyant flame dynamics in wildfire spread.

Author information

1
Missoula Fire Sciences Laboratory, US Forest Service, Missoula, MT 59808; mfinney@fs.fed.us.
2
Missoula Fire Sciences Laboratory, US Forest Service, Missoula, MT 59808;
3
Department of Fire Protection Engineering, University of Maryland, College Park, MD 20742-3031;
4
Department of Mechanical Engineering, University of Kentucky, Lexington, KY 40506-0503.

Abstract

Large wildfires of increasing frequency and severity threaten local populations and natural resources and contribute carbon emissions into the earth-climate system. Although wildfires have been researched and modeled for decades, no verifiable physical theory of spread is available to form the basis for the precise predictions needed to manage fires more effectively and reduce their environmental, economic, ecological, and climate impacts. Here, we report new experiments conducted at multiple scales that appear to reveal how wildfire spread derives from the tight coupling between flame dynamics induced by buoyancy and fine-particle response to convection. Convective cooling of the fine-sized fuel particles in wildland vegetation is observed to efficiently offset heating by thermal radiation until convective heating by contact with flames and hot gasses occurs. The structure and intermittency of flames that ignite fuel particles were found to correlate with instabilities induced by the strong buoyancy of the flame zone itself. Discovery that ignition in wildfires is critically dependent on nonsteady flame convection governed by buoyant and inertial interaction advances both theory and the physical basis for practical modeling.

KEYWORDS:

buoyant instability; convective heating; flame spread; wildfires

PMID:
26183227
PMCID:
PMC4538634
DOI:
10.1073/pnas.1504498112
[Indexed for MEDLINE]
Free PMC Article

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